diff options
Diffstat (limited to 'tools/perf/Documentation/perf-record.txt')
| -rw-r--r-- | tools/perf/Documentation/perf-record.txt | 44 |
1 files changed, 42 insertions, 2 deletions
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt index fa8a5fcd27ab..3f72d8e261f3 100644 --- a/tools/perf/Documentation/perf-record.txt +++ b/tools/perf/Documentation/perf-record.txt @@ -407,8 +407,9 @@ if combined with -a or -C options. -D:: --delay=:: -After starting the program, wait msecs before measuring. This is useful to -filter out the startup phase of the program, which is often very different. +After starting the program, wait msecs before measuring (-1: start with events +disabled). This is useful to filter out the startup phase of the program, which +is often very different. -I:: --intr-regs:: @@ -626,6 +627,45 @@ option. The -e option and this one can be mixed and matched. Events can be grouped using the {} notation. endif::HAVE_LIBPFM[] +--control fd:ctl-fd[,ack-fd] +Listen on ctl-fd descriptor for command to control measurement ('enable': enable events, +'disable': disable events). Measurements can be started with events disabled using +--delay=-1 option. Optionally send control command completion ('ack\n') to ack-fd descriptor +to synchronize with the controlling process. Example of bash shell script to enable and +disable events during measurements: + +#!/bin/bash + +ctl_dir=/tmp/ + +ctl_fifo=${ctl_dir}perf_ctl.fifo +test -p ${ctl_fifo} && unlink ${ctl_fifo} +mkfifo ${ctl_fifo} +exec {ctl_fd}<>${ctl_fifo} + +ctl_ack_fifo=${ctl_dir}perf_ctl_ack.fifo +test -p ${ctl_ack_fifo} && unlink ${ctl_ack_fifo} +mkfifo ${ctl_ack_fifo} +exec {ctl_fd_ack}<>${ctl_ack_fifo} + +perf record -D -1 -e cpu-cycles -a \ + --control fd:${ctl_fd},${ctl_fd_ack} \ + -- sleep 30 & +perf_pid=$! + +sleep 5 && echo 'enable' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "enabled(${e1})" +sleep 10 && echo 'disable' >&${ctl_fd} && read -u ${ctl_fd_ack} d1 && echo "disabled(${d1})" + +exec {ctl_fd_ack}>&- +unlink ${ctl_ack_fifo} + +exec {ctl_fd}>&- +unlink ${ctl_fifo} + +wait -n ${perf_pid} +exit $? + + SEE ALSO -------- linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-intel-pt[1] |