NAME

       funccount - count kernel function calls matching specified wildcards. Uses Linux ftrace.

SYNOPSIS

       funccount [-hT] [-i secs] [-d secs] [-t top] funcstring

DESCRIPTION

       This  tool is a quick way to determine which kernel functions are being called, and at what rate. It uses
       ftrace function profiling capabilities.

       WARNING: This uses dynamic tracing of (what can be many) kernel functions, and could cause kernel  panics
       or freezes. Test, and know what you are doing, before use.

       Since this uses ftrace, only the root user can use this tool.

REQUIREMENTS

       CONFIG_FUNCTION_PROFILER, which you may already have enabled and available on recent kernels, and awk.

OPTIONS

       -d seconds Total duration of the trace.

       -h     Print usage message.

       -i seconds
              Print an interval summary every so many seconds.

       -t top Print top number of entries only.

       -T     Include timestamp on each summary.

       funcstring
              A  function  name  to trace, which may include file glob style wildcards ("*") at the beginning or
              ending of a string only. Eg, "vfs*" means match "vfs" followed by anything.

EXAMPLES

       Count every kernel function beginning with "bio_", until Ctrl-C is hit:
              # funccount 'bio_*'

       Count every "tcp_*" kernel function, and print a summary every one second, five in total:
              # funccount -i 1 -d 5 'tcp_*'

       Count every "ext4*" kernel function, and print the top 20 when Ctrl-C is hit:
              # funccount -t 20 'ext4*'

FIELDS

       FUNC   Kernel function name.

       COUNT  Number of times this function was called during the tracing interval.

OVERHEAD

       This uses the ftrace profiling framework, which does in-kernel counts, lowering the overhead (compared to
       tracing each event).

SOURCE

       This is from the perf-tools collection:

              https://github.com/brendangregg/perf-tools

       Also look under the examples directory for a text file containing example usage, output,  and  commentary
       for this tool.

OS

       Linux

STABILITY

       Unstable - in development.

AUTHOR

       Brendan Gregg

SEE ALSO

       functrace(8)

USER COMMANDS                                      2014-07-19                                       funccount(8)