.TH funccount 8  "2015-08-18" "USER COMMANDS"
.SH NAME
funccount \- Count function, tracepoint, and USDT probe calls matching a pattern. Uses Linux eBPF/bcc.
.SH SYNOPSIS
.B funccount [\-h] [\-p PID] [\-i INTERVAL] [\-d DURATION] [\-T] [\-r] [\-c CPU] [\-D] pattern
.SH DESCRIPTION
This tool is a quick way to determine which functions are being called,
and at what rate. It uses in-kernel eBPF maps to count function calls.

WARNING: This uses dynamic tracing of (what can be many) functions, an
activity that has had issues on some kernel versions (risk of panics or
freezes). Test, and know what you are doing, before use.

Since this uses BPF, only the root user can use this tool.
.SH REQUIREMENTS
CONFIG_BPF and bcc.
.SH OPTIONS
pattern
Search pattern. Supports "*" wildcards. See EXAMPLES. You can also use \-r for regular expressions.
.TP
\-h
Print usage message.
.TP
\-p PID
Trace this process ID only.
.TP
\-i INTERVAL
Print output every interval seconds.
.TP
\-d DURATION
Total duration of trace in seconds.
.TP
\-T
Include timestamps on output.
.TP
\-r
Use regular expressions for the search pattern.
.TP
\-D
Print the BPF program before starting (for debugging purposes).
.TP
\-c CPU
Trace on this CPU only.
.SH EXAMPLES
.TP
Count kernel functions beginning with "vfs_", until Ctrl-C is hit:
#
.B funccount 'vfs_*'
.TP
Count kernel functions beginning with "tcp_send", until Ctrl-C is hit:
#
.B funccount 'tcp_send*'
.TP
Print kernel functions beginning with "vfs_", every second:
#
.B funccount \-i 1 'vfs_*'
.TP
Print kernel functions beginning with "vfs_", for ten seconds only:
#
.B funccount \-d 10 'vfs_*'
.TP
Match kernel functions beginning with "vfs_", using regular expressions:
#
.B funccount \-r '^vfs_.*'
.TP
Count vfs calls for process ID 181 only:
#
.B funccount \-p 181 'vfs_*'
.TP
Count calls to the sched_fork tracepoint, indicating a fork() performed:
#
.B funccount t:sched:sched_fork
.TP
Count all GC USDT probes in the Node process:
#
.B funccount -p 185 u:node:gc*
.TP
Count all malloc() calls in libc:
#
.B funccount c:malloc
.TP
Count kernel functions beginning with "vfs_" on CPU 1 only:
#
.B funccount \-c 1 'vfs_*'
.SH FIELDS
.TP
FUNC
Function name
.TP
COUNT
Number of calls while tracing
.SH OVERHEAD
This traces functions and maintains in-kernel counts, which
are asynchronously copied to user-space. While the rate of calls
be very high (>1M/sec), this is a relatively efficient way to trace these
events, and so the overhead is expected to be small for normal workloads.
Measure in a test environment before use.
.SH SOURCE
This is from bcc.
.IP
https://github.com/iovisor/bcc
.PP
Also look in the bcc distribution for a companion _examples.txt file containing
example usage, output, and commentary for this tool.
.SH OS
Linux
.SH STABILITY
Unstable - in development.
.SH AUTHOR
Brendan Gregg, Sasha Goldshtein
.SH SEE ALSO
stackcount(8)
funclatency(8)
vfscount(8)