Provided by: atop_2.7.1-1_amd64 
NAME
atop - Advanced System & Process Monitor
SYNOPSIS
Interactive Usage:
atop [-g|-m|-d|-n|-u|-p|-s|-c|-v|-o|-y|-Y] [-C|-M|-D|-N|-A] [-afFG1xR] [-L linelen] [-Plabel[,label]...
[-Z]] [ interval [ samples ]]
Writing and reading raw logfiles:
atop -w rawfile [-a] [-S] [ interval [ samples ]]
atop -r [ rawfile ] [-b [YYYYMMDD]hhmm ] [-e [YYYYMMDD]hhmm ] [-g|-m|-d|-n|-u|-p|-s|-c|-v|-o|-y|-Y]
[-C|-M|-D|-N|-A] [-fFG1xR] [-L linelen] [-Plabel[,label]... [-Z]]
DESCRIPTION
The program atop is an interactive monitor to view the load on a Linux system. It shows the occupation
of the most critical hardware resources (from a performance point of view) on system level, i.e. cpu,
memory, disk and network.
It also shows which processes are responsible for the indicated load with respect to cpu and memory load
on process level. Disk load is shown per process if "storage accounting" is active in the kernel.
Network load is shown per process if the kernel module `netatop' has been installed.
The initial screen shows if atop runs with restricted view (unprivileged) or unrestricted view
(privileged). In case of restricted view atop does not have the privileges (root identity or necessary
capabilities) to retrieve all counter values on system level and on process level.
Every interval (default: 10 seconds) information is shown about the resource occupation on system level
(cpu, memory, disks and network layers), followed by a list of processes which have been active during
the last interval (note that all processes that were unchanged during the last interval are not shown,
unless the key 'a' has been pressed or unless sorting on memory occupation is done). If the list of
active processes does not entirely fit on the screen, only the top of the list is shown (sorted in order
of activity).
The intervals are repeated till the number of samples (specified as command argument) is reached, or till
the key 'q' is pressed in interactive mode.
When atop is started, it checks whether the standard output channel is connected to a screen, or to a
file/pipe. In the first case it produces screen control codes (via the ncurses library) and behaves
interactively; in the second case it produces flat ASCII-output.
In interactive mode, the output of atop scales dynamically to the current dimensions of the
screen/window.
If the window is resized horizontally, columns will be added or removed automatically. For this purpose,
every column has a particular weight. The columns with the highest weights that fit within the current
width will be shown.
If the window is resized vertically, lines of the process/thread list will be added or removed
automatically.
Furthermore in interactive mode the output of atop can be controlled by pressing particular keys.
However it is also possible to specify such key as flag on the command line. In that case atop switches
to the indicated mode on beforehand; this mode can be modified again interactively. Specifying such key
as flag is especially useful when running atop with output to a pipe or file (non-interactively). These
flags are the same as the keys that can be pressed in interactive mode (see section INTERACTIVE
COMMANDS).
Additional flags are available to support storage of atop-data in raw format (see section RAW DATA
STORAGE).
PROCESS ACCOUNTING
With every interval, atop reads the kernel administration to obtain information about all running
processes. However, it is likely that during the interval also processes have terminated. These
processes might have consumed system resources during this interval as well before they terminated.
Therefor, atop tries to read the process accounting records that contain the accounting information of
terminated processes and report these processes too. Only when the process accounting mechanism in the
kernel is activated, the kernel writes such process accounting record to a file for every process that
terminates.
There are various ways for atop to get access to the process accounting records (tried in this order):
1. When the environment variable ATOPACCT is set, it specifies the name of the process accounting file.
In that case, process accounting for this file should have been activated on beforehand. Before
opening this file for reading, atop drops its root privileges (if any).
When this environment variable is present but its contents is empty, process accounting will not be
used at all.
2. This is the preferred way of handling process accounting records!
When the atopacctd daemon is active, it has activated the process accounting mechanism in the kernel
and transfers to original accounting records to shadow files. In that case, atop drops its root
privileges and opens the current shadow file for reading.
This way is preferred, because the atopacctd daemon maintains full control of the size of the
original process accounting file written by the kernel and the shadow files read by the atop
process(es).
The atopacct service will be activated before the atop service to enable atop to detect that process
accounting is managed by the atopacctd daemon. As a forking service, atopacctd takes care that all
directories and files are initialized before the parent process dies. The child process continues as
the daemon process.
For further information, refer to the atopacctd man page.
3. When the atopacctd daemon is not active, atop verifies if the process accounting mechanism has been
switched on via the separate psacct or acct package (the package name depends on the Linux distro).
In that case, one of the files /var/log/pacct, /var/account/pacct or /var/log/account/pacct is in use
as process accounting file and atop opens this file for reading.
4. As a last possibility, atop itself tries to activate the process accounting mechanism (requires root
privileges) using the file /var/cache/atop.d/atop.acct (to be written by the kernel, to be read by
atop itself). Process accounting remains active as long as at least one atop process is alive.
Whenever the last atop process stops (either by pressing `q' or by `kill -15'), it deactivates the
process accounting mechanism again. Therefor you should never terminate atop by `kill -9', because
then it has no chance to stop process accounting. As a result, the accounting file may consume a lot
of disk space after a while.
To avoid that the process accounting file consumes too much disk space, atop verifies at the end of
every sample if the size of the process accounting file exceeds 200 MiB and if this atop process is
the only one that is currently using the file. In that case the file is truncated to a size of zero.
Notice that root-privileges are required to switch on/off process accounting in the kernel. You can
start atop as a root user or specify setuid-root privileges to the executable file. In the latter
case, atop switches on process accounting and drops the root-privileges again.
If atop does not run with root-privileges, it does not show information about finished processes. It
indicates this situation with the message message `no procacct` in the top-right corner (instead of
the counter that shows the number of exited processes).
When during one interval a lot of processes have finished, atop might grow tremendously in memory when
reading all process accounting records at the end of the interval. To avoid such excessive growth, atop
will never read more than 50 MiB with process information from the process accounting file per interval
(approx. 70000 finished processes). In interactive mode a warning is given whenever processes have been
skipped for this reason.
COLORS
For the resource consumption on system level, atop uses colors to indicate that a critical occupation
percentage has been (almost) reached. A critical occupation percentage means that is likely that this
load causes a noticeable negative performance influence for applications using this resource. The
critical percentage depends on the type of resource: e.g. the performance influence of a disk with a busy
percentage of 80% might be more noticeable for applications/user than a CPU with a busy percentage of
90%.
Currently atop uses the following default values to calculate a weighted percentage per resource:
Processor
A busy percentage of 90% or higher is considered `critical'.
Disk
A busy percentage of 70% or higher is considered `critical'.
Network
A busy percentage of 90% or higher for the load of an interface is considered `critical'.
Memory
An occupation percentage of 90% is considered `critical'. Notice that this occupation percentage is
the accumulated memory consumption of the kernel (including slab) and all processes; the memory for
the page cache (`cache' and `buff' in the MEM-line) and the reclaimable part of the slab (`slrec`)
is not implied!
If the number of pages swapped out (`swout' in the PAG-line) is larger than 10 per second, the
memory resource is considered `critical'. A value of at least 1 per second is considered `almost
critical'.
If the committed virtual memory exceeds the limit (`vmcom' and `vmlim' in the SWP-line), the SWP-
line is colored due to overcommitting the system.
Swap
An occupation percentage of 80% is considered `critical' because swap space might be completely
exhausted in the near future; it is not critical from a performance point-of-view.
These default values can be modified in the configuration file (see separate man-page of atoprc).
When a resource exceeds its critical occupation percentage, the concerning values in the screen line are
colored red by default.
When a resource exceeded (default) 80% of its critical percentage (so it is almost critical), the
concerning values in the screen line are colored cyan by default. This `almost critical percentage' (one
value for all resources) can be modified in the configuration file (see separate man-page of atoprc).
The default colors red and cyan can be modified in the configuration file as well (see separate man-page
of atoprc).
With the key 'x' (or flag -x), the use of colors can be suppressed.
NETATOP MODULE
Per-process and per-thread network activity can be measured by the netatop kernel module. You can
download this kernel module from the website (mentioned at the end of this manual page) and install it on
your system if the kernel version is 2.6.24 or newer.
When atop gathers counters for a new interval, it verifies if the netatop module is currently active. If
so, atop obtains the relevant network counters from this module and shows the number of sent and received
packets per process/thread in the generic screen. Besides, detailed counters can be requested by pressing
the `n' key.
When the netatopd daemon is running as well, atop also reads the network counters of exited processes
that are logged by this daemon (comparable with process accounting).
More information about the optional netatop kernel module and the netatopd daemon can be found in the
concerning man-pages and on the website mentioned at the end of this manual page.
GPU STATISTICS GATHERING
GPU statistics can be gathered by atopgpud which is a separate data collection daemon process. It
gathers cumulative utilization counters of every Nvidia GPU in the system, as well as utilization
counters of every process that uses a GPU. When atop notices that the daemon is active, it reads these
GPU utilization counters with every interval.
The atopgpud daemon is written in Python, so a Python interpreter should be installed on the target
system. The Python code of the daemon is compatible with Python version 2 and version 3. For the
gathering of the statistics, the pynvml module is used by the daemon. Be sure that this module is
installed on the target system before activating the daemon, by running the command as root pip (the
command pip might be exchanged by pip3 in case of Python3):
pip install nvidia-ml-py
The atopgpud daemon is installed by default as part of the atop package, but it is not automatically
enabled. The daemon can be enabled and started now by running the following commands (as root):
systemctl enable atopgpu
systemctl start atopgpu
Find a description about the utilization counters in the section OUTPUT DESCRIPTION.
INTERACTIVE COMMANDS
When running atop interactively (no output redirection), keys can be pressed to control the output. In
general, lower case keys can be used to show other information for the active processes and upper case
keys can be used to influence the sort order of the active process/thread list.
g Show generic output (default).
Per process the following fields are shown in case of a window-width of 80 positions: process-id,
cpu consumption during the last interval in system and user mode, the virtual and resident memory
growth of the process.
The subsequent columns depend on the used kernel:
When the kernel supports "storage accounting" (>= 2.6.20), the data transfer for read/write on disk,
the status and exit code are shown for each process. When the kernel does not support "storage
accounting", the username, number of threads in the thread group, the status and exit code are
shown.
When the kernel module 'netatop' is loaded, the data transfer for send/receive of network packets is
shown for each process.
The last columns contain the state, the occupation percentage for the chosen resource (default: cpu)
and the process name.
When more than 80 positions are available, other information is added.
m Show memory related output.
Per process the following fields are shown in case of a window-width of 80 positions: process-id,
minor and major memory faults, size of virtual shared text, total virtual process size, total
resident process size, virtual and resident growth during last interval, memory occupation
percentage and process name.
When more than 80 positions are available, other information is added.
For memory consumption, always all processes are shown (also the processes that were not active
during the interval).
d Show disk-related output.
When "storage accounting" is active in the kernel, the following fields are shown: process-id,
amount of data read from disk, amount of data written to disk, amount of data that was written but
has been withdrawn again (WCANCL), disk occupation percentage and process name.
n Show network related output.
Per process the following fields are shown in case of a window-width of 80 positions: process-id,
thread-id, total bandwidth for received packets, total bandwidth for sent packets, number of
received TCP packets with the average size per packet (in bytes), number of sent TCP packets with
the average size per packet (in bytes), number of received UDP packets with the average size per
packet (in bytes), number of sent UDP packets with the average size per packet (in bytes), the
network occupation percentage and process name.
This information can only be shown when kernel module `netatop' is installed.
When more than 80 positions are available, other information is added.
s Show scheduling characteristics.
Per process the following fields are shown in case of a window-width of 80 positions: process-id,
number of threads in state 'running' (R), number of threads in state 'interruptible sleeping' (S),
number of threads in state 'uninterruptible sleeping' (D), scheduling policy (normal timesharing,
realtime round-robin, realtime fifo), nice value, priority, realtime priority, current processor,
status, exit code, state, the occupation percentage for the chosen resource and the process name.
When more than 80 positions are available, other information is added.
v Show various process characteristics.
Per process the following fields are shown in case of a window-width of 80 positions: process-id,
user name and group, start date and time, status (e.g. exit code if the process has finished),
state, the occupation percentage for the chosen resource and the process name.
When more than 80 positions are available, other information is added.
c Show the command line of the process.
Per process the following fields are shown: process-id, the occupation percentage for the chosen
resource and the command line including arguments.
e Show GPU utilization.
Per process at least the following fields are shown: process-id, range of GPU numbers on which the
process currently runs, GPU busy percentage on all GPUs, memory busy percentage (i.e. read and write
accesses on memory) on all GPUs, memory occupation at the moment of the sample, average memory
occupation during the sample, and GPU percentage.
When the atopgpud daemon does not run with root privileges, the GPU busy percentage and the memory
busy percentage are not available on process level. In that case, the GPU percentage on process
level reflects the GPU memory occupation instead of the GPU busy percentage (which is preferred).
o Show the user-defined line of the process.
In the configuration file the keyword ownprocline can be specified with the description of a user-
defined output-line.
Refer to the man-page of atoprc for a detailed description.
y Show the individual threads within a process (toggle).
Single-threaded processes are still shown as one line.
For multi-threaded processes, one line represents the process while additional lines show the
activity per individual thread (in a different color). Depending on the option 'a' (all or active
toggle), all threads are shown or only the threads that were active during the last interval.
Depending on the option 'Y' (sort threads), the threads per process will be sorted on the chosen
sort criterium or not.
Whether this key is active or not can be seen in the header line.
Y Sort the threads per process when combined with option 'y' (toggle).
u Show the process activity accumulated per user.
Per user the following fields are shown: number of processes active or terminated during last
interval (or in total if combined with command `a'), accumulated cpu consumption during last
interval in system and user mode, the current virtual and resident memory space consumed by active
processes (or all processes of the user if combined with command `a').
When "storage accounting" is active in the kernel, the accumulated read and write throughput on disk
is shown. When the kernel module `netatop' has been installed, the number of received and sent
network packets are shown.
The last columns contain the accumulated occupation percentage for the chosen resource (default:
cpu) and the user name.
p Show the process activity accumulated per program (i.e. process name).
Per program the following fields are shown: number of processes active or terminated during last
interval (or in total if combined with command `a'), accumulated cpu consumption during last
interval in system and user mode, the current virtual and resident memory space consumed by active
processes (or all processes of the user if combined with command `a').
When "storage accounting" is active in the kernel, the accumulated read and write throughput on disk
is shown. When the kernel module `netatop' has been installed, the number of received and sent
network packets are shown.
The last columns contain the accumulated occupation percentage for the chosen resource (default:
cpu) and the program name.
j Show the process activity accumulated per Docker container.
Per container the following fields are shown: number of processes active or terminated during last
interval (or in total if combined with command `a'), accumulated cpu consumption during last
interval in system and user mode, the current virtual and resident memory space consumed by active
processes (or all processes of the user if combined with command `a').
When "storage accounting" is active in the kernel, the accumulated read and write throughput on disk
is shown. When the kernel module `netatop' has been installed, the number of received and sent
network packets are shown.
The last columns contain the accumulated occupation percentage for the chosen resource (default:
cpu) and the Docker container id (CID).
C Sort the current list in the order of cpu consumption (default). The one-but-last column changes to
``CPU''.
E Sort the current list in the order of GPU utilization (preferred, but only applicable when the
atopgpud daemon runs under root privileges) or the order of GPU memory occupation). The one-but-
last column changes to ``GPU''.
M Sort the current list in the order of resident memory consumption. The one-but-last column changes
to ``MEM''. In case of sorting on memory, the full process list will be shown (not only the active
processes).
D Sort the current list in the order of disk accesses issued. The one-but-last column changes to
``DSK''.
N Sort the current list in the order of network bandwidth (received and transmitted). The one-but-
last column changes to ``NET''.
A Sort the current list automatically in the order of the most busy system resource during this
interval. The one-but-last column shows either ``ACPU'', ``AMEM'', ``ADSK'' or ``ANET'' (the
preceding 'A' indicates automatic sorting-order). The most busy resource is determined by comparing
the weighted busy-percentages of the system resources, as described earlier in the section COLORS.
This option remains valid until another sorting-order is explicitly selected again.
A sorting-order for disk is only possible when "storage accounting" is active. A sorting-order for
network is only possible when the kernel module `netatop' is loaded.
Miscellaneous interactive commands:
? Request for help information (also the key 'h' can be pressed).
V Request for version information (version number and date).
R Gather and calculate the proportional set size of processes (toggle). Gathering of all values that
are needed to calculate the PSIZE of a process is a very time-consuming task, so this key should
only be active when analyzing the resident memory consumption of processes.
W Get the WCHAN per thread (toggle). Gathering of the WCHAN string per thread is a relatively time-
consuming task, so this key should only be made active when analyzing the reason for threads to be
in sleep state.
x Suppress colors to highlight critical resources (toggle).
Whether this key is active or not can be seen in the header line.
z The pause key can be used to freeze the current situation in order to investigate the output on the
screen. While atop is paused, the keys described above can be pressed to show other information
about the current list of processes. Whenever the pause key is pressed again, atop will continue
with a next sample.
i Modify the interval timer (default: 10 seconds). If an interval timer of 0 is entered, the interval
timer is switched off. In that case a new sample can only be triggered manually by pressing the key
't'.
t Trigger a new sample manually. This key can be pressed if the current sample should be finished
before the timer has exceeded, or if no timer is set at all (interval timer defined as 0). In the
latter case atop can be used as a stopwatch to measure the load being caused by a particular
application transaction, without knowing on beforehand how many seconds this transaction will last.
When viewing the contents of a raw file this key can be used to show the next sample from the file.
This key can also be used when viewing raw data via a pipe.
T When viewing the contents of a raw file this key can be used to show the previous sample from the
file, however not when reading raw data from a pipe.
b When viewing the contents of a raw file, this key can be used to branch to a certain timestamp
within the file either forward or backward. When viewing raw data from a pipe only forward branches
are possible.
r Reset all counters to zero to see the system and process activity since boot again.
When viewing the contents of a raw file, this key can be used to rewind to the beginning of the file
again (except when reading raw data from a pipe).
U Specify a search string for specific user names as a regular expression. From now on, only (active)
processes will be shown from a user which matches the regular expression. The system statistics are
still system wide. If the Enter-key is pressed without specifying a name, (active) processes of all
users will be shown again.
Whether this key is active or not can be seen in the header line.
I Specify a list with one or more PIDs to be selected. From now on, only processes will be shown with
a PID which matches one of the given list. The system statistics are still system wide. If the
Enter-key is pressed without specifying a PID, all (active) processes will be shown again.
Whether this key is active or not can be seen in the header line.
P Specify a search string for specific process names as a regular expression. From now on, only
processes will be shown with a name which matches the regular expression. The system statistics are
still system wide. If the Enter-key is pressed without specifying a name, all (active) processes
will be shown again.
Whether this key is active or not can be seen in the header line.
/ Specify a specific command line search string as a regular expression. From now on, only processes
will be shown with a command line which matches the regular expression. The system statistics are
still system wide. If the Enter-key is pressed without specifying a string, all (active) processes
will be shown again.
Whether this key is active or not can be seen in the header line.
J Specify a Docker container id of 12 (hexadecimal) characters. From now on, only processes will be
shown that run in that specific Docker container (CID). The system statistics are still system
wide. If the Enter-key is pressed without specifying a container id, all (active) processes will be
shown again.
Whether this key is active or not can be seen in the header line.
Q Specify a comma-separated list of process/thread state characters. From now on, only
processes/threads will be shown that are in those specific states. Accepted states are: R
(running), S (sleeping), D (disk sleep), I (idle), T (stopped), t (tracing stop), X (dead), Z
(zombie) and P (parked). The system statistics are still system wide. If the Enter-key is pressed
without specifying a state, all (active) processes/threads will be shown again.
Whether this key is active or not can be seen in the header line.
S Specify search strings for specific logical volume names, specific disk names and specific network
interface names. All search strings are interpreted as a regular expressions. From now on, only
those system resources are shown that match the concerning regular expression. If the Enter-key is
pressed without specifying a search string, all (active) system resources of that type will be shown
again.
Whether this key is active or not can be seen in the header line.
a The `all/active' key can be used to toggle between only showing/accumulating the processes that were
active during the last interval (default) or showing/accumulating all processes.
Whether this key is active or not can be seen in the header line.
G By default, atop shows/accumulates the processes that are alive and the processes that are exited
during the last interval. With this key (toggle), showing/accumulating the processes that are exited
can be suppressed.
Whether this key is active or not can be seen in the header line.
f Show a fixed (maximum) number of header lines for system resources (toggle). By default only the
lines are shown about system resources (CPUs, paging, logical volumes, disks, network interfaces)
that really have been active during the last interval. With this key you can force atop to show
lines of inactive resources as well.
Whether this key is active or not can be seen in the header line.
F Suppress sorting of system resources (toggle). By default system resources (CPUs, logical volumes,
disks, network interfaces) are sorted on utilization.
Whether this key is active or not can be seen in the header line.
1 Show relevant counters as an average per second (in the format `..../s') instead of as a total
during the interval (toggle).
Whether this key is active or not can be seen in the header line.
l Limit the number of system level lines for the counters per-cpu, the active disks and the network
interfaces. By default lines are shown of all CPUs, disks and network interfaces which have been
active during the last interval. Limiting these lines can be useful on systems with huge number
CPUs, disks or interfaces in order to be able to run atop on a screen/window with e.g. only 24
lines.
For all mentioned resources the maximum number of lines can be specified interactively. When using
the flag -l the maximum number of per-cpu lines is set to 0, the maximum number of disk lines to 5
and the maximum number of interface lines to 3. These values can be modified again in interactive
mode.
k Send a signal to an active process (a.k.a. kill a process).
q Quit the program.
PgDn Show the next page of the process/thread list.
With the arrow-down key the list can be scrolled downwards with single lines.
^F Show the next page of the process/thread list (forward).
With the arrow-down key the list can be scrolled downwards with single lines.
PgUp Show the previous page of the process/thread list.
With the arrow-up key the list can be scrolled upwards with single lines.
^B Show the previous page of the process/thread list (backward).
With the arrow-up key the list can be scrolled upwards with single lines.
^L Redraw the screen.
RAW DATA STORAGE
In order to store system and process level statistics for long-term analysis (e.g. to check the system
load and the active processes running yesterday between 3:00 and 4:00 PM), atop can store the system and
process level statistics in compressed binary format in a raw file with the flag -w followed by the
filename. If this file already exists and is recognized as a raw data file, atop will append new samples
to the file (starting with a sample which reflects the activity since boot); if the file does not exist,
it will be created.
All information about processes and threads is stored in the raw file.
The interval (default: 10 seconds) and number of samples (default: infinite) can be passed as last
arguments. Instead of the number of samples, the flag -S can be used to indicate that atop should finish
anyhow before midnight.
A raw file can be read and visualized again with the flag -r followed by the filename. If no filename is
specified, the file /var/log/atop/atop_YYYYMMDD is opened for input (where YYYYMMDD are digits
representing the current date). If a filename is specified in the format YYYYMMDD (representing any
valid date), the file /var/log/atop/atop_YYYYMMDD is opened. If a filename with the symbolic name y is
specified, yesterday's daily logfile is opened (this can be repeated so 'yyyy' indicates the logfile of
four days ago). If the filename - is used, stdin will be read.
The samples from the file can be viewed interactively by using the key 't' to show the next sample, the
key 'T' to show the previous sample, the key 'b' to branch to a particular time or the key 'r' to rewind
to the begin of the file.
When output is redirected to a file or pipe, atop prints all samples in plain ASCII. The default line
length is 80 characters in that case; with the flag -L followed by an alternate line length, more (or
less) columns will be shown.
With the flag -b (begin time) and/or -e (end time) followed by a time argument of the form
[YYYYMMDD]hhmm, a certain time period within the raw file can be selected.
Every day at midnight atop is restarted to write compressed binary data to the file
/var/log/atop/atop_YYYYMMDD with an interval of 10 minutes by default.
Furthermore all raw files are removed that are older than 28 days (by default).
The mentioned default values can be overruled in the file /etc/default/atop that might contain other
values for LOGOPTS (by default without any flag), LOGINTERVAL (in seconds, by default 600),
LOGGENERATIONS (in days, by default 28), and LOGPATH (directory in which logfiles are stored).
Unfortunately, it is not always possible to keep the format of the raw files compatible in newer versions
of atop especially when lots of new counters have to be maintained. Therefore, the program atopconvert
is installed to convert a raw file created by an older version of atop to a raw file that can be read by
a newer version of atop (see the man page of atopconvert for more details).
OUTPUT DESCRIPTION
The first sample shows the system level activity since boot (the elapsed time in the header shows the
time since boot). Note that particular counters could have reached their maximum value (several times)
and started by zero again, so do not rely on these figures.
For every sample atop first shows the lines related to system level activity. If a particular system
resource has not been used during the interval, the entire line related to this resource is suppressed.
So the number of system level lines may vary for each sample.
After that a list is shown of processes which have been active during the last interval. This list is by
default sorted on cpu consumption, but this order can be changed by the keys which are previously
described.
If values have to be shown by atop which do not fit in the column width, another format is used. If e.g.
a cpu-consumption of 233216 milliseconds should be shown in a column width of 4 positions, it is shown as
`233s' (in seconds). For large memory figures, another unit is chosen if the value does not fit (Mb
instead of Kb, Gb instead of Mb, Tb instead of Gb, ...). For other values, a kind of exponent notation
is used (value 123456789 shown in a column of 5 positions gives 123e6).
OUTPUT DESCRIPTION - SYSTEM LEVEL
The system level information consists of the following output lines:
PRC Process and thread level totals.
This line contains the total cpu time consumed in system mode (`sys') and in user mode (`user'), the
total number of processes present at this moment (`#proc'), the total number of threads present at
this moment in state `running' (`#trun'), `sleeping interruptible' (`#tslpi') and `sleeping
uninterruptible' (`#tslpu'), the number of zombie processes (`#zombie'), the number of clone system
calls (`clones'), and the number of processes that ended during the interval (`#exit') when process
accounting is used. Instead of `#exit` the last column may indicate that process accounting could
not be activated (`no procacct`).
If the screen-width does not allow all of these counters, only a relevant subset is shown.
CPU CPU utilization.
At least one line is shown for the total occupation of all CPUs together.
In case of a multi-processor system, an additional line is shown for every individual processor
(with `cpu' in lower case), sorted on activity. Inactive CPUs will not be shown by default. The
lines showing the per-cpu occupation contain the cpu number in the field combined with the wait
percentage.
Every line contains the percentage of cpu time spent in kernel mode by all active processes (`sys'),
the percentage of cpu time consumed in user mode (`user') for all active processes (including
processes running with a nice value larger than zero), the percentage of cpu time spent for
interrupt handling (`irq') including softirq, the percentage of unused cpu time while no processes
were waiting for disk I/O (`idle'), and the percentage of unused cpu time while at least one process
was waiting for disk I/O (`wait').
In case of per-cpu occupation, the cpu number and the wait percentage (`w') for that cpu. The
number of lines showing the per-cpu occupation can be limited.
For virtual machines, the steal-percentage (`steal') shows the percentage of cpu time stolen by
other virtual machines running on the same hardware.
For physical machines hosting one or more virtual machines, the guest-percentage (`guest') shows the
percentage of cpu time used by the virtual machines. Notice that this percentage overlaps the user
percentage!
When PMC performance monitoring counters are supported by the CPU and the kernel (and atop runs with
root privileges), the number of instructions per CPU cycle (`ipc') is shown. The first sample
always shows the value 'initial', because the counters are just activated at the moment that atop is
started.
When the CPU busy percentage is high and the IPC is less than 1.0, it is likely that the CPU is
frequently waiting for memory access during instruction execution (larger CPU caches or faster
memory might be helpful to improve performance). When the CPU busy percentage is high and the IPC
is greater than 1.0, it is likely that the CPU is instruction-bound (more/faster cores might be
helpful to improve performance).
Furthermore, per CPU the effective number of cycles (`cycl') is shown. This value can reach the
current CPU frequency if such CPU is 100% busy. When an idle CPU is halted, the number of effective
cycles can be (considerably) lower than the current frequency.
Notice that the average instructions per cycle and number of cycles is shown in the CPU line for all
CPUs.
Beware that reading the cycle counter in virtual machines (guests) might introduce performance
delays. Therefore this metric is by default disabled in virtual machines. However, with the keyword
'perfevents' in the atoprc file this metric can be explicitly set to 'enable' or 'disable' (see
separate man-page of atoprc).
See also: http://www.brendangregg.com/blog/2017-05-09/cpu-utilization-is-wrong.html
In case of frequency scaling, all previously mentioned CPU percentages are relative to the used
scaling of the CPU during the interval. If a CPU has been active for e.g. 50% in user mode during
the interval while the frequency scaling of that CPU was 40%, only 20% of the full capacity of the
CPU has been used in user mode.
In case that the kernel module `cpufreq_stats' is active (after issueing `modprobe cpufreq_stats'),
the average frequency (`avgf') and the average scaling percentage (`avgscal') is shown. Otherwise
the current frequency (`curf') and the current scaling percentage (`curscal') is shown at the moment
that the sample is taken. Notice that average values for frequency and scaling are shown in the CPU
line for every CPU.
Frequency scaling statistics are only gathered for systems with maximum 8 CPUs, since gathering of
these values per CPU is very time consuming.
If the screen-width does not allow all of these counters, only a relevant subset is shown.
CPL CPU load information.
This line contains the load average figures reflecting the number of threads that are available to
run on a CPU (i.e. part of the runqueue) or that are waiting for disk I/O. These figures are
averaged over 1 (`avg1'), 5 (`avg5') and 15 (`avg15') minutes.
Furthermore the number of context switches (`csw'), the number of serviced interrupts (`intr') and
the number of available CPUs are shown.
If the screen-width does not allow all of these counters, only a relevant subset is shown.
GPU GPU utilization (Nvidia).
Read the section GPU STATISTICS GATHERING in this document to find the details about the activation
of the atopgpud daemon.
In the first column of every line, the bus-id (last nine characters) and the GPU number are shown.
The subsequent columns show the percentage of time that one or more kernels were executing on the
GPU (`gpubusy'), the percentage of time that global (device) memory was being read or written
(`membusy'), the occupation percentage of memory (`memocc'), the total memory (`total'), the memory
being in use at the moment of the sample (`used'), the average memory being in use during the sample
time (`usavg'), the number of processes being active on the GPU at the moment of the sample
(`#proc'), and the type of GPU.
If the screen-width does not allow all of these counters, only a relevant subset is shown.
The number of lines showing the GPUs can be limited.
MEM Memory occupation.
This line contains the total amount of physical memory (`tot'), the amount of memory which is
currently free (`free'), the amount of memory in use as page cache including the total resident
shared memory (`cache'), the amount of memory within the page cache that has to be flushed to disk
(`dirty'), the amount of memory used for filesystem meta data (`buff'), the amount of memory being
used for kernel mallocs (`slab'), the amount of slab memory that is reclaimable (`slrec'), the
resident size of shared memory including tmpfs (`shmem`), the resident size of shared memory
(`shrss`) the amount of shared memory that is currently swapped (`shswp`), the amount of memory that
is currently claimed by vmware's balloon driver (`vmbal`), the amount of memory that is currently
claimed by the ARC (cache) of ZFSonlinux (`zfarc`), the amount of memory that is claimed for huge
pages (`hptot`), the amount of huge page memory that is really in use (`hpuse`), and the number of
NUMA nodes in this system (`numnode').
If the screen-width does not allow all of these counters, only a relevant subset is shown.
SWP Swap occupation and overcommit info.
This line contains the total amount of swap space on disk (`tot'), the amount of free swap space
(`free'), the size of the swap cache (`swcac'), the total size of compressed storage in zswap
(`zpool`), the total size of the compressed pages stored in zswap (`zstor'), the total size of the
memory used for KSM (`ksuse`, i.e. shared), and the total size of the memory saved (deduped) by KSM
(`kssav`, i.e. sharing).
Furthermore the committed virtual memory space (`vmcom') and the maximum limit of the committed
space (`vmlim', which is by default swap size plus 50% of memory size) is shown. The committed
space is the reserved virtual space for all allocations of private memory space for processes. The
kernel only verifies whether the committed space exceeds the limit if strict overcommit handling is
configured (vm.overcommit_memory is 2).
NUM Memory utilization per NUMA node.
This line shows the total amount of physical memory of this node (`tot'), the amount of free memory
(`free'), the amount of memory for cached file data (`file'), modified cached file data (`dirty'),
recently used memory (`activ'), less recently used memory (`inact'), memory being used for kernel
mallocs (`slab'), the amount of slab memory that is reclaimable (`slrec'), shared memory including
tmpfs (`shmem'), total huge pages (`hptot') and the fragmentation percentage (`frag').
NUC CPU utilization per NUMA node (not shown in case of a single NUMA node).
This line shows the utilization percentages of all CPUs related to this NUMA node, categorized for
system mode (`sys'), user mode (`user'), user mode for niced processes (`niced'), idle mode
(`idle'), wait mode (`w' preceded by the node number), irq mode (`irq'), softirq mode (`sirq'),
steal mode (`steal'), and guest mode (`guest') overlapping user mode.
PAG Paging frequency.
This line contains the number of scanned pages (`scan') due to the fact that free memory drops below
a particular threshold, the number times that the kernel tries to reclaim pages due to an urgent
need (`stall'), the number of process stalls to run memory compaction to allocate huge pages
(`compact'), the number of NUMA pages migrated (`numamig'), and the total number of memory pages
migrated succesfully e.g. between NUMA nodes or for compaction (`migrate') are shown.
Also the number of memory pages the system read from swap space (`swin'), the number of memory pages
the system wrote to swap space (`swout'), and the number of out-of-memory kills (`oomkill').
PSI Pressure Stall Information.
This line contains percentages about resource pressure related to CPU, memory and I/O. Certain
percentages refer to 'some' meaning that some processes/threads were delayed due to resource
overload. Other percentages refer to 'full' meaning a loss of overall throughput due to resource
overload.
The values `cpusome', `memsome', `memfull', `iosome' and `iofull' show the pressure percentage
during the entire interval.
The values `cs' (cpu some), `ms' (memory some), `mf' (memory full), `is' (I/O some) and `if' (I/O
full) each show three percentages separated by slashes: pressure percentage over the last 10, 60 and
300 seconds.
LVM/MDD/DSK
Logical volume/multiple device/disk utilization.
Per active unit one line is produced, sorted on unit activity. Such line shows the name (e.g.
VolGroup00-lvtmp for a logical volume or sda for a hard disk), the busy percentage i.e. the portion
of time that the unit was busy handling requests (`busy'), the number of read requests issued
(`read'), the number of write requests issued (`write'), the number of discard requests issued
(`discrd') if supported by kernel version, the number of KiBytes per read (`KiB/r'), the number of
KiBytes per write (`KiB/w'), the number of KiBytes per discard (`KiB/d') if supported by kernel
version, the number of MiBytes per second throughput for reads (`MBr/s'), the number of MiBytes per
second throughput for writes (`MBw/s'), the average queue depth (`avq') and the average number of
milliseconds needed by a request (`avio') for seek, latency and data transfer.
If the screen-width does not allow all of these counters, only a relevant subset is shown.
The number of lines showing the units can be limited per class (LVM, MDD or DSK) with the 'l' key or
statically (see separate man-page of atoprc). By specifying the value 0 for a particular class, no
lines will be shown any more for that class.
NFM Network Filesystem (NFS) mount at the client side.
For each NFS-mounted filesystem, a line is shown that contains the mounted server directory, the
name of the server (`srv'), the total number of bytes physically read from the server (`read') and
the total number of bytes physically written to the server (`write'). Data transfer is subdivided
in the number of bytes read via normal read() system calls (`nread'), the number of bytes written
via normal read() system calls (`nwrit'), the number of bytes read via direct I/O (`dread'), the
number of bytes written via direct I/O (`dwrit'), the number of bytes read via memory mapped I/O
pages (`mread'), and the number of bytes written via memory mapped I/O pages (`mwrit').
NFC Network Filesystem (NFS) client side counters.
This line contains the number of RPC calls issues by local processes (`rpc'), the number of read RPC
calls (`read`) and write RPC calls (`rpwrite') issued to the NFS server, the number of RPC calls
being retransmitted (`retxmit') and the number of authorization refreshes (`autref').
NFS Network Filesystem (NFS) server side counters.
This line contains the number of RPC calls received from NFS clients (`rpc'), the number of read RPC
calls received (`cread`), the number of write RPC calls received (`cwrit'), the number of
Megabytes/second returned to read requests by clients (`MBcr/s`), the number of Megabytes/second
passed in write requests by clients (`MBcw/s`), the number of network requests handled via TCP
(`nettcp'), the number of network requests handled via UDP (`netudp'), the number of reply cache
hits (`rchits'), the number of reply cache misses (`rcmiss') and the number of uncached requests
(`rcnoca'). Furthermore some error counters indicating the number of requests with a bad format
(`badfmt') or a bad authorization (`badaut'), and a counter indicating the number of bad clients
(`badcln').
NET Network utilization (TCP/IP).
One line is shown for activity of the transport layer (TCP and UDP), one line for the IP layer and
one line per active interface.
For the transport layer, counters are shown concerning the number of received TCP segments including
those received in error (`tcpi'), the number of transmitted TCP segments excluding those containing
only retransmitted octets (`tcpo'), the number of UDP datagrams received (`udpi'), the number of UDP
datagrams transmitted (`udpo'), the number of active TCP opens (`tcpao'), the number of passive TCP
opens (`tcppo'), the number of TCP output retransmissions (`tcprs'), the number of TCP input errors
(`tcpie'), the number of TCP output resets (`tcpor'), the number of UDP no ports (`udpnp'), and the
number of UDP input errors (`udpie').
If the screen-width does not allow all of these counters, only a relevant subset is shown.
These counters are related to IPv4 and IPv6 combined.
For the IP layer, counters are shown concerning the number of IP datagrams received from interfaces,
including those received in error (`ipi'), the number of IP datagrams that local higher-layer
protocols offered for transmission (`ipo'), the number of received IP datagrams which were forwarded
to other interfaces (`ipfrw'), the number of IP datagrams which were delivered to local higher-layer
protocols (`deliv'), the number of received ICMP datagrams (`icmpi'), and the number of transmitted
ICMP datagrams (`icmpo').
If the screen-width does not allow all of these counters, only a relevant subset is shown.
These counters are related to IPv4 and IPv6 combined.
For every active network interface one line is shown, sorted on the interface activity. Such line
shows the name of the interface and its busy percentage in the first column. The busy percentage
for half duplex is determined by comparing the interface speed with the number of bits transmitted
and received per second; for full duplex the interface speed is compared with the highest of either
the transmitted or the received bits. When the interface speed can not be determined (e.g. for the
loopback interface), `---' is shown instead of the percentage.
Furthermore the number of received packets (`pcki'), the number of transmitted packets (`pcko'), the
line speed of the interface (`sp'), the effective amount of bits received per second (`si'), the
effective amount of bits transmitted per second (`so'), the number of collisions (`coll'), the
number of received multicast packets (`mlti'), the number of errors while receiving a packet
(`erri'), the number of errors while transmitting a packet (`erro'), the number of received packets
dropped (`drpi'), and the number of transmitted packets dropped (`drpo').
If the screen-width does not allow all of these counters, only a relevant subset is shown.
The number of lines showing the network interfaces can be limited.
IFB Infiniband utilization.
For every active Infiniband port one line is shown, sorted on activity. Such line shows the name of
the port and its busy percentage in the first column. The busy percentage is determined by taking
the highest of either the transmitted or the received bits during the interval, multiplying that
value by the number of lanes and comparing it against the maximum port speed.
Furthermore the number of received packets divided by the number of lanes (`pcki'), the number of
transmitted packets divided by the number of lanes (`pcko'), the maximum line speed (`sp'), the
effective amount of bits received per second (`si'), the effective amount of bits transmitted per
second (`so'), and the number of lanes (`lanes').
If the screen-width does not allow all of these counters, only a relevant subset is shown.
The number of lines showing the Infiniband ports can be limited.
OUTPUT DESCRIPTION - PROCESS LEVEL
Following the system level information, the processes are shown from which the resource utilization has
changed during the last interval. These processes might have used cpu time or issued disk or network
requests. However a process is also shown if part of it has been paged out due to lack of memory (while
the process itself was in sleep state).
Per process the following fields may be shown (in alphabetical order), depending on the current output
mode as described in the section INTERACTIVE COMMANDS and depending on the current width of your window:
AVGRSZ The average size of one read-action on disk.
AVGWSZ The average size of one write-action on disk.
BANDWI Total bandwidth for received TCP and UDP packets consumed by this process (bits-per-second).
This value can be compared with the value `si' on interface level (used bandwidth per
interface).
This information will only be shown when the kernel module `netatop' is loaded.
BANDWO Total bandwidth for sent TCP and UDP packets consumed by this process (bits-per-second). This
value can be compared with the value `so' on interface level (used bandwidth per interface).
This information will only be shown when the kernel module `netatop' is loaded.
CID Container ID (Docker) of 12 hexadecimal digits, referring to the container in which the
process/thread is running. If a process has been started and finished during the last interval,
a `?' is shown because the container ID is not part of the standard process accounting record.
CMD The name of the process. This name can be surrounded by "less/greater than" signs (`<name>')
which means that the process has finished during the last interval.
Behind the abbreviation `CMD' in the header line, the current page number and the total number
of pages of the process/thread list are shown.
COMMAND-LINE
The full command line of the process (including arguments). If the length of the command line
exceeds the length of the screen line, the arrow keys -> and <- can be used for horizontal
scroll.
Behind the verb `COMMAND-LINE' in the header line, the current page number and the total number
of pages of the process/thread list are shown.
CPU The occupation percentage of this process related to the available capacity for this resource on
system level.
CPUNR The identification of the CPU the (main) thread is running on or has recently been running on.
CTID Container ID (OpenVZ). If a process has been started and finished during the last interval, a
`?' is shown because the container ID is not part of the standard process accounting record.
DSK The occupation percentage of this process related to the total load that is produced by all
processes (i.e. total disk accesses by all processes during the last interval).
This information is shown when per process "storage accounting" is active in the kernel.
EGID Effective group-id under which this process executes.
ENDATE Date that the process has been finished. If the process is still running, this field shows
`active'.
ENTIME Time that the process has been finished. If the process is still running, this field shows
`active'.
ENVID Virtual environment identified (OpenVZ only).
EUID Effective user-id under which this process executes.
EXC The exit code of a terminated process (second position of column `ST' is E) or the fatal signal
number (second position of column `ST' is S or C).
FSGID Filesystem group-id under which this process executes.
FSUID Filesystem user-id under which this process executes.
GPU When the atopgpud daemon does not run with root privileges, the GPU percentage reflects the GPU
memory occupation percentage (memory of all GPUs is 100%).
When the atopgpud daemon runs with root privileges, the GPU percentage reflects the GPU busy
percentage.
GPUBUSY Busy percentage on all GPUs (one GPU is 100%).
When the atopgpud daemon does not run with root privileges, this value is not available.
GPUNUMS Comma-separated list of GPUs used by the process during the interval. When the comma-separated
list exceeds the width of the column, a hexadecimal value is shown.
LOCKSZ The virtual amount of memory being locked (i.e. non-swappable) by this process (or user).
MAJFLT The number of page faults issued by this process that have been solved by creating/loading the
requested memory page.
MEM The occupation percentage of this process related to the available capacity for this resource on
system level.
MEMAVG Average memory occupation during the interval on all used GPUs.
MEMBUSY Busy percentage of memory on all GPUs (one GPU is 100%), i.e. the time needed for read and
write accesses on memory.
When the atopgpud daemon does not run with root privileges, this value is not available.
MEMNOW Memory occupation at the moment of the sample on all used GPUs.
MINFLT The number of page faults issued by this process that have been solved by reclaiming the
requested memory page from the free list of pages.
NET The occupation percentage of this process related to the total load that is produced by all
processes (i.e. consumed network bandwidth of all processes during the last interval).
This information will only be shown when kernel module `netatop' is loaded.
NICE The more or less static priority that can be given to a process on a scale from -20 (high
priority) to +19 (low priority).
NPROCS The number of active and terminated processes accumulated for this user or program.
PID Process-id. If a process has been started and finished during the last interval, a `?' is shown
because the process-id is not part of the standard process accounting record.
POLI The policies 'norm' (normal, which is SCHED_OTHER), 'btch' (batch) and 'idle' refer to
timesharing processes. The policies 'fifo' (SCHED_FIFO) and 'rr' (round robin, which is
SCHED_RR) refer to realtime processes.
PPID Parent process-id. If a process has been started and finished during the last interval, value 0
is shown because the parent process-id is not part of the standard process accounting record.
PRI The process' priority ranges from 0 (highest priority) to 139 (lowest priority). Priority 0 to
99 are used for realtime processes (fixed priority independent of their behavior) and priority
100 to 139 for timesharing processes (variable priority depending on their recent CPU
consumption and the nice value).
PSIZE The proportional memory size of this process (or user).
Every process shares resident memory with other processes. E.g. when a particular program is
started several times, the code pages (text) are only loaded once in memory and shared by all
incarnations. Also the code of shared libraries is shared by all processes using that shared
library, as well as shared memory and memory-mapped files. For the PSIZE calculation of a
process, the resident memory of a process that is shared with other processes is divided by the
number of sharers. This means, that every process is accounted for a proportional part of that
memory. Accumulating the PSIZE values of all processes in the system gives a reliable impression
of the total resident memory consumed by all processes.
Since gathering of all values that are needed to calculate the PSIZE is a very time-consuming
task, the 'R' key (or '-R' flag) should be active. Gathering these values also requires
superuser privileges (otherwise '?K' is shown in the output).
If a process has finished during the last interval, no value is shown since the proportional
memory size is not part of the standard process accounting record.
RDDSK When the kernel maintains standard io statistics (>= 2.6.20):
The read data transfer issued physically on disk (so reading from the disk cache is not
accounted for).
Unfortunately, the kernel aggregates the data tranfer of a process to the data transfer of its
parent process when terminating, so you might see transfers for (parent) processes like cron,
bash or init, that are not really issued by them.
RDELAY Runqueue delay, i.e. time spent waiting on a runqueue.
RGID The real group-id under which the process executes.
RGROW The amount of resident memory that the process has grown during the last interval. A resident
growth can be caused by touching memory pages which were not physically created/loaded before
(load-on-demand). Note that a resident growth can also be negative e.g. when part of the
process is paged out due to lack of memory or when the process frees dynamically allocated
memory. For a process which started during the last interval, the resident growth reflects the
total resident size of the process at that moment.
If a process has finished during the last interval, no value is shown since resident memory
occupation is not part of the standard process accounting record.
RNET The number of TCP- and UDP packets received by this process. This information will only be
shown when kernel module `netatop' is installed.
If a process has finished during the last interval, no value is shown since network counters are
not part of the standard process accounting record.
RSIZE The total resident memory usage consumed by this process (or user). Notice that the RSIZE of a
process includes all resident memory used by that process, even if certain memory parts are
shared with other processes (see also the explanation of PSIZE).
If a process has finished during the last interval, no value is shown since resident memory
occupation is not part of the standard process accounting record.
RTPR Realtime priority according the POSIX standard. Value can be 0 for a timesharing process
(policy 'norm', 'btch' or 'idle') or ranges from 1 (lowest) till 99 (highest) for a realtime
process (policy 'rr' or 'fifo').
RUID The real user-id under which the process executes.
S The current state of the (main) thread: `R' for running (currently processing or in the
runqueue), `S' for sleeping interruptible (wait for an event to occur), `D' for sleeping non-
interruptible, `Z' for zombie (waiting to be synchronized with its parent process), `T' for
stopped (suspended or traced), `W' for swapping, and `E' (exit) for processes which have
finished during the last interval.
SGID The saved group-id of the process.
SNET The number of TCP and UDP packets transmitted by this process. This information will only be
shown when the kernel module `netatop' is loaded.
ST The status of a process.
The first position indicates if the process has been started during the last interval (the value
N means 'new process').
The second position indicates if the process has been finished during the last interval.
The value E means 'exit' on the process' own initiative; the exit code is displayed in the
column `EXC'.
The value S means that the process has been terminated unvoluntarily by a signal; the signal
number is displayed in the in the column `EXC'.
The value C means that the process has been terminated unvoluntarily by a signal, producing a
core dump in its current directory; the signal number is displayed in the column `EXC'.
STDATE The start date of the process.
STTIME The start time of the process.
SUID The saved user-id of the process.
SWAPSZ The swap space consumed by this process (or user).
SYSCPU CPU time consumption of this process in system mode (kernel mode), usually due to system call
handling.
TCPRASZ The average size of a received TCP buffer in bytes. This information will only be shown when
the kernel module `netatop' is loaded.
TCPRCV The number of TCP packets received for this process. This information will only be shown when
the kernel module `netatop' is loaded.
TCPSASZ The average size of a transmitted TCP buffer in bytes. This information will only be shown when
the kernel module `netatop' is loaded.
TCPSND The number of TCP packets transmitted for this process. This information will only be shown
when the kernel module `netatop' is loaded.
THR Total number of threads within this process. All related threads are contained in a thread
group, represented by atop as one line or as a separate line when the 'y' key (or -y flag) is
active.
On Linux 2.4 systems it is hardly possible to determine which threads (i.e. processes) are
related to the same thread group. Every thread is represented by atop as a separate line.
TID Thread-id. All threads within a process run with the same PID but with a different TID. This
value is shown for individual threads in multi-threaded processes (when using the key 'y').
TRUN Number of threads within this process that are in the state 'running' (R).
TSLPI Number of threads within this process that are in the state 'interruptible sleeping' (S).
TSLPU Number of threads within this process that are in the state 'uninterruptible sleeping' (D).
UDPRASZ The average size of a received UDP packet in bytes. This information will only be shown when
the kernel module `netatop' is loaded.
UDPRCV The number of UDP packets received by this process. This information will only be shown when
the kernel module `netatop' is loaded.
UDPSASZ The average size of a transmitted UDP packets in bytes. This information will only be shown
when the kernel module `netatop' is loaded.
UDPSND The number of UDP packets transmitted by this process. This information will only be shown when
the kernel module `netatop' is loaded.
USRCPU CPU time consumption of this process in user mode, due to processing the own program text.
VDATA The virtual memory size of the private data used by this process (including heap and shared
library data).
VGROW The amount of virtual memory that the process has grown during the last interval. A virtual
growth can be caused by e.g. issueing a malloc() or attaching a shared memory segment. Note that
a virtual growth can also be negative by e.g. issueing a free() or detaching a shared memory
segment. For a process which started during the last interval, the virtual growth reflects the
total virtual size of the process at that moment.
If a process has finished during the last interval, no value is shown since virtual memory
occupation is not part of the standard process accounting record.
VPID Virtual process-id (within an OpenVZ container). If a process has been started and finished
during the last interval, a `?' is shown because the virtual process-id is not part of the
standard process accounting record.
VSIZE The total virtual memory usage consumed by this process (or user).
If a process has finished during the last interval, no value is shown since virtual memory
occupation is not part of the standard process accounting record.
VSLIBS The virtual memory size of the (shared) text of all shared libraries used by this process.
VSTACK The virtual memory size of the (private) stack used by this process
VSTEXT The virtual memory size of the (shared) text of the executable program.
WCHAN Wait channel of thread in sleep state, i.e. the name of the kernel function in which the thread
has been put asleep.
Since determining the name string of the kernel function is a relatively time-consuming task,
the 'W' key (or '-W' flag) should be active.
WRDSK When the kernel maintains standard io statistics (>= 2.6.20):
The write data transfer issued physically on disk (so writing to the disk cache is not accounted
for). This counter is maintained for the application process that writes its data to the cache
(assuming that this data is physically transferred to disk later on). Notice that disk I/O
needed for swapping is not taken into account.
Unfortunately, the kernel aggregates the data tranfer of a process to the data transfer of its
parent process when terminating, so you might see transfers for (parent) processes like cron,
bash or init, that are not really issued by them.
WCANCL When the kernel maintains standard io statistics (>= 2.6.20):
The write data transfer previously accounted for this process or another process that has been
cancelled. Suppose that a process writes new data to a file and that data is removed again
before the cache buffers have been flushed to disk. Then the original process shows the written
data as WRDSK, while the process that removes/truncates the file shows the unflushed removed
data as WCANCL.
PARSEABLE OUTPUT
With the flag -P followed by a list of one or more labels (comma-separated), parseable output is produced
for each sample. The labels that can be specified for system-level statistics correspond to the labels
(first verb of each line) that can be found in the interactive output: "CPU", "cpu", "CPL", "GPU", "MEM",
"SWP", "PAG", "PSI", "LVM", "MDD", "DSK", "NFM", "NFC", "NFS", "NET", "IFB", "NUM" and "NUC".
For process-level statistics special labels are available: "PRG" (general), "PRC" (cpu), "PRE" (GPU),
"PRM" (memory), "PRD" (disk, only if "storage accounting" is active) and "PRN" (network, only if the
kernel module 'netatop' has been installed).
With the label "ALL", all system and process level statistics are shown.
The command and command line in the parseable output might contain spaces and are therefore by default
surrounded by parenthesis. However, since a space is often used as separator between the fields by
parsing tools, with the additional flag -Z it is possible to exchange the spaces in the command (line) by
underscores and omit the parenthesis.
For every interval all requested lines are shown whereafter atop shows a line just containing the label
"SEP" as a separator before the lines for the next sample are generated.
When a sample contains the values since boot, atop shows a line just containing the label "RESET" before
the lines for this sample are generated.
The first part of each output-line consists of the following six fields: label (the name of the label),
host (the name of this machine), epoch (the time of this interval as number of seconds since 1-1-1970),
date (date of this interval in format YYYY/MM/DD), time (time of this interval in format HH:MM:SS), and
interval (number of seconds elapsed for this interval).
The subsequent fields of each output-line depend on the label:
CPU Subsequent fields: total number of clock-ticks per second for this machine, number of
processors, consumption for all CPUs in system mode (clock-ticks), consumption for all CPUs in
user mode (clock-ticks), consumption for all CPUs in user mode for niced processes (clock-
ticks), consumption for all CPUs in idle mode (clock-ticks), consumption for all CPUs in wait
mode (clock-ticks), consumption for all CPUs in irq mode (clock-ticks), consumption for all CPUs
in softirq mode (clock-ticks), consumption for all CPUs in steal mode (clock-ticks), consumption
for all CPUs in guest mode (clock-ticks) overlapping user mode, frequency of all CPUs, frequency
percentage of all CPUs, instructions executed by all CPUs and cycles for all CPUs.
cpu Subsequent fields: total number of clock-ticks per second for this machine, processor-number,
consumption for this CPU in system mode (clock-ticks), consumption for this CPU in user mode
(clock-ticks), consumption for this CPU in user mode for niced processes (clock-ticks),
consumption for this CPU in idle mode (clock-ticks), consumption for this CPU in wait mode
(clock-ticks), consumption for this CPU in irq mode (clock-ticks), consumption for this CPU in
softirq mode (clock-ticks), consumption for this CPU in steal mode (clock-ticks), consumption
for this CPU in guest mode (clock-ticks) overlapping user mode, frequency of this CPU, frequency
percentage of this CPU, instructions executed by this CPU and cycles for this CPU.
CPL Subsequent fields: number of processors, load average for last minute, load average for last
five minutes, load average for last fifteen minutes, number of context-switches, and number of
device interrupts.
GPU Subsequent fields: GPU number, bus-id string, type of GPU string, GPU busy percentage during
last second (-1 if not available), memory busy percentage during last second (-1 if not
available), total memory size (KiB), used memory (KiB) at this moment, number of samples taken
during interval, cumulative GPU busy percentage during the interval (to be divided by the number
of samples for the average busy percentage, -1 if not available), cumulative memory busy
percentage during the interval (to be divided by the number of samples for the average busy
percentage, -1 if not available), and cumulative memory occupation during the interval (to be
divided by the number of samples for the average occupation).
MEM Subsequent fields: page size for this machine (in bytes), size of physical memory (pages), size
of free memory (pages), size of page cache (pages), size of buffer cache (pages), size of slab
(pages), dirty pages in cache (pages), reclaimable part of slab (pages), total size of vmware's
balloon pages (pages), total size of shared memory (pages), size of resident shared memory
(pages), size of swapped shared memory (pages), huge page size (in bytes), total size of huge
pages (huge pages), size of free huge pages (huge pages), size of ARC (cache) of ZFSonlinux
(pages), size of sharing pages for KSM (pages), and size of shared pages for KSM (pages).
SWP Subsequent fields: page size for this machine (in bytes), size of swap (pages), size of free
swap (pages), size of swap cache (pages), size of committed space (pages), limit for committed
space (pages), size of the swap cache (pages), size of compressed pages stored in zswap (pages),
and total size of compressed pool in zswap (pages).
PAG Subsequent fields: page size for this machine (in bytes), number of page scans, number of
allocstalls, 0 (future use), number of swapins, number of swapouts, number of oomkills (-1 when
counter not present), number of process stalls to run memory compaction, number of pages
successfully migrated in total, and number of NUMA pages migrated.
PSI Subsequent fields: PSI statistics present on this system (n or y), CPU some avg10, CPU some
avg60, CPU some avg300, CPU some accumulated microseconds during interval, memory some avg10,
memory some avg60, memory some avg300, memory some accumulated microseconds during interval,
memory full avg10, memory full avg60, memory full avg300, memory full accumulated microseconds
during interval, I/O some avg10, I/O some avg60, I/O some avg300, I/O some accumulated
microseconds during interval, I/O full avg10, I/O full avg60, I/O full avg300, and I/O full
accumulated microseconds during interval.
LVM/MDD/DSK
For every logical volume/multiple device/hard disk one line is shown.
Subsequent fields: name, number of milliseconds spent for I/O, number of reads issued, number of
sectors transferred for reads, number of writes issued, number of sectors transferred for write,
number of discards issued (-1 if not supported), and number of sectors transferred for discards.
NFM Subsequent fields: mounted NFS filesystem, total number of bytes read, total number of bytes
written, number of bytes read by normal system calls, number of bytes written by normal system
calls, number of bytes read by direct I/O, number of bytes written by direct I/O, number of
pages read by memory-mapped I/O, and number of pages written by memory-mapped I/O.
NFC Subsequent fields: number of transmitted RPCs, number of transmitted read RPCs, number of
transmitted write RPCs, number of RPC retransmissions, and number of authorization refreshes.
NFS Subsequent fields: number of handled RPCs, number of received read RPCs, number of received
write RPCs, number of bytes read by clients, number of bytes written by clients, number of RPCs
with bad format, number of RPCs with bad authorization, number of RPCs from bad client, total
number of handled network requests, number of handled network requests via TCP, number of
handled network requests via UDP, number of handled TCP connections, number of hits on reply
cache, number of misses on reply cache, and number of uncached requests.
NET First, one line is produced for the upper layers of the TCP/IP stack.
Subsequent fields: the verb "upper", number of packets received by TCP, number of packets
transmitted by TCP, number of packets received by UDP, number of packets transmitted by UDP,
number of packets received by IP, number of packets transmitted by IP, number of packets
delivered to higher layers by IP, number of packets forwarded by IP, number of input errors
(UDP), number of noport errors (UDP), number of active opens (TCP), number of passive opens
(TCP), number of passive opens (TCP), number of established connections at this moment (TCP),
number of retransmitted segments (TCP), number of input errors (TCP), and number of output
resets (TCP).
Next, one line is shown for every interface.
Subsequent fields: name of the interface, number of packets received by the interface, number of
bytes received by the interface, number of packets transmitted by the interface, number of bytes
transmitted by the interface, interface speed, and duplex mode (0=half, 1=full).
IFB Subsequent fields: name of the InfiniBand interface, port number, number of lanes, maximum rate
(Mbps), number of bytes received, number of bytes transmitted, number of packets received, and
number of packets transmitted.
NUM Subsequent fields: NUMA node number, page size for this machine (in bytes), the fragmentation
percentage of this node, size of physical memory (pages), size of free memory (pages), recently
(active) used memory (pages), less recently (inactive) used memory (pages), size of cached file
data (pages), dirty pages in cache (pages), slab memory being used for kernel mallocs (pages),
slab memory that is reclaimable (pages), shared memory including tmpfs (pages), and total huge
pages (pages).
NUC Subsequent fields: NUMA node number, number of processors for this node, consumption for node
CPUs in system mode (clock-ticks), consumption for node CPUs in user mode (clock-ticks),
consumption for node CPUs in user mode for niced processes (clock-ticks), consumption for node
CPUs in idle mode (clock-ticks), consumption for node CPUs in wait mode (clock-ticks),
consumption for node CPUs in irq mode (clock-ticks), consumption for node CPUs in softirq mode
(clock-ticks), consumption for node CPUs in steal mode (clock-ticks), and consumption for node
CPUs in guest mode (clock-ticks) overlapping user mode.
PRG For every process one line is shown.
Subsequent fields: PID (unique ID of task), name (between parenthesis or underscores for
spaces), state, real uid, real gid, TGID (group number of related tasks/threads), total number
of threads, exit code (in case of fatal signal: signal number + 256), start time (epoch), full
command line (between parenthesis or underscores for spaces), PPID, number of threads in state
'running' (R), number of threads in state 'interruptible sleeping' (S), number of threads in
state 'uninterruptible sleeping' (D), effective uid, effective gid, saved uid, saved gid,
filesystem uid, filesystem gid, elapsed time (hertz), is_process (y/n), OpenVZ virtual pid
(VPID), OpenVZ container id (CTID), Docker container id (CID), and indication if the task is
newly started during this interval ('N').
PRC For every process one line is shown.
Subsequent fields: PID, name (between parenthesis or underscores for spaces), state, total
number of clock-ticks per second for this machine, CPU-consumption in user mode (clockticks),
CPU-consumption in system mode (clockticks), nice value, priority, realtime priority, scheduling
policy, current CPU, sleep average, TGID (group number of related tasks/threads), is_process
(y/n), runqueue delay in nanoseconds for this thread or for all threads (in case of process),
and wait channel of this thread (between parenthesis or underscores for spaces).
PRE For every process one line is shown.
Subsequent fields: PID, name (between parenthesis or underscores for spaces), process state, GPU
state (A for active, E for exited, N for no GPU user), number of GPUs used by this process,
bitlist reflecting used GPUs, GPU busy percentage during interval, memory busy percentage during
interval, memory occupation (KiB) at this moment cumulative memory occupation (KiB) during
interval, and number of samples taken during interval.
PRM For every process one line is shown.
Subsequent fields: PID, name (between parenthesis or underscores for spaces), state, page size
for this machine (in bytes), virtual memory size (Kbytes), resident memory size (Kbytes), shared
text memory size (Kbytes), virtual memory growth (Kbytes), resident memory growth (Kbytes),
number of minor page faults, number of major page faults, virtual library exec size (Kbytes),
virtual data size (Kbytes), virtual stack size (Kbytes), swap space used (Kbytes), TGID (group
number of related tasks/threads), is_process (y/n), proportional set size (Kbytes) if in 'R'
option is specified and virtually locked memory space (Kbytes).
PRD For every process one line is shown.
Subsequent fields: PID, name (between parenthesis or underscores for spaces), state, obsoleted
kernel patch installed ('n'), standard io statistics used ('y' or 'n'), number of reads on disk,
cumulative number of sectors read, number of writes on disk, cumulative number of sectors
written, cancelled number of written sectors, TGID (group number of related tasks/threads),
obsoleted value ('n'), and is_process (y/n).
If the standard I/O statistics (>= 2.6.20) are not used, the disk I/O counters per process are
not relevant. The counters 'number of reads on disk' and 'number of writes on disk' are
obsoleted anyhow.
PRN For every process one line is shown.
Subsequent fields: PID, name (between parenthesis or underscores for spaces), state, kernel
module 'netatop' loaded ('y' or 'n'), number of TCP-packets transmitted, cumulative size of TCP-
packets transmitted, number of TCP-packets received, cumulative size of TCP-packets received,
number of UDP-packets transmitted, cumulative size of UDP-packets transmitted, number of UDP-
packets received, cumulative size of UDP-packets transmitted, number of raw packets transmitted
(obsolete, always 0), number of raw packets received (obsolete, always 0), TGID (group number of
related tasks/threads) and is_process (y/n).
If the kernel module is not active, the network I/O counters per process are not relevant.
SIGNALS
By sending the SIGUSR1 signal to atop a new sample will be forced, even if the current timer interval has
not exceeded yet. The behavior is similar to pressing the `t` key in an interactive session.
By sending the SIGUSR2 signal to atop a final sample will be forced after which atop will terminate.
EXAMPLES
To monitor the current system load interactively with an interval of 5 seconds:
atop 5
To monitor the system load and write it to a file (in plain ASCII) with an interval of one minute during
half an hour with active processes sorted on memory consumption:
atop -M 60 30 > /log/atop.mem
Store information about the system and process activity in binary compressed form to a file with an
interval of ten minutes during an hour:
atop -w /tmp/atop.raw 600 6
View the contents of this file interactively:
atop -r /tmp/atop.raw
View the processor and disk utilization of this file in parseable format:
atop -PCPU,DSK -r /tmp/atop.raw
View the contents of today's standard logfile interactively:
atop -r
View the contents of the standard logfile of the day before yesterday interactively:
atop -r yy
View the contents of the standard logfile of 2014, June 7 from 02:00 PM onwards interactively:
atop -r 20140607 -b 1400
Concatenate all raw log files of January 2020 and generate parsable output about the CPU utilization:
atopcat /var/log/atop/atop_202001?? | atop -r - -PCPU
FILES
/run/pacct_shadow.d/
Directory containing the process accounting shadow files that are used by atop when the atopacctd
daemon is active.
/var/cache/atop.d/atop.acct
File in which the kernel writes the accounting records when atop itself has activated the process
accounting mechanism.
/etc/atoprc
Configuration file containing system-wide default values. See related man-page.
~/.atoprc
Configuration file containing personal default values. See related man-page.
/etc/default/atop
Configuration file to overrule the settings of atop that runs in the background to create the daily
logfile. This file is created when atop is installed. The default settings are:
LOGOPTS=""
LOGINTERVAL=600
LOGGENERATIONS=28
/var/log/atop/atop_YYYYMMDD
Raw file, where YYYYMMDD are digits representing the current date. This name is used by atop
running in the background as default name for the output file, and by atop as default name for the
input file when using the -r flag.
All binary system and process level data in this file has been stored in compressed format.
/run/netatop.log
File that contains the netpertask structs containing the network counters of exited processes. These
structs are written by the netatopd daemon and read by atop after reading the standard process
accounting records.
SEE ALSO
atopsar(1), atopconvert(1), atopcat(1), atoprc(5), atopacctd(8), netatop(4), netatopd(8), atopgpud(8),
logrotate(8)
https://www.atoptool.nl
AUTHOR
Gerlof Langeveld (gerlof.langeveld@atoptool.nl)
JC van Winkel
Linux December 2021 ATOP(1)