Messages in this thread | | | From | Alexey Budankov <> | Subject | [PATCH v1 0/8] perf: support resume and pause commands in stat and record modes | Date | Fri, 27 Mar 2020 11:34:54 +0300 |
| |
The patch set implements handling of 'start paused', 'resume' and 'pause' external control commands which can be provided for stat and record modes of the tool from an external controlling process. 'start paused' command can be used to postpone enabling of events in the beginning of a monitoring session. 'resume' and 'pause' commands can be used to enable and disable events correspondingly any time after the start of the session.
The 'start paused', resume and 'pause' external control commands can be used to focus measurement on specially selected time intervals of workload execution. Focused measurement reduces tool intrusion and influence on workload behavior, reduces distortion and amount of collected and stored data, mitigates data accuracy loss because measurement and data capturing happen only during intervals of interest.
A controlling process can be a bash shell script [1], native executable or any other language program that can directly work with file descriptors, e.g. pipes [2], and spawn a process, specially the tool one.
-D,--delay <val> option is extended with -1 value to skip events enabling in the beginning of a monitoring session ('start paused' command). --ctl-fd and --ctl-fd-ack command line options are introduced to provide the tool with a pair of file descriptors to listen to 'resume' and 'pause' commands and reply to an external controlling process on the completion of received commands processing.
The tool reads two byte control command message from ctl-fd descriptor, handles the command and optionally replies two bytes acknowledgement message to fd-ack descriptor, if it is specified on the command line. 'resume' command is recognized as 'r' character message and 'pause' command is recognized as 'p' character message both received from ctl-fd descriptor. Completion message is 'a''\n' and sent to fd-ack descriptor.
Bash script demonstrating simple use case follows:
#!/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 stat -D -1 -e cpu-cycles -a -I 1000 \ --ctl-fd ${ctl_fd} --ctl-fd-ack ${ctl_fd_ack} \ -- sleep 40 & perf_pid=$!
sleep 5 && echo 'r' >&${ctl_fd} && read -u ${ctl_fd_ack} r1 && echo "resumed(${r1})" sleep 10 && echo 'p' >&${ctl_fd} && read -u ${ctl_fd_ack} p1 && echo "paused(${p1})" sleep 5 && echo 'r' >&${ctl_fd} && read -u ${ctl_fd_ack} r2 && echo "resumed(${r2})" sleep 10 && echo 'p' >&${ctl_fd} && read -u ${ctl_fd_ack} p2 && echo "paused(${p2})"
exec {ctl_fd_ack}>&- && unlink ${ctl_ack_fifo} exec {ctl_fd}>&- && unlink ${ctl_fifo}
wait -n ${perf_pid} exit $?
Script output:
[root@host acme] example Monitoring paused # time counts unit events 1.001101062 <not counted> cpu-cycles 2.002994944 <not counted> cpu-cycles 3.004864340 <not counted> cpu-cycles 4.006727177 <not counted> cpu-cycles Monitoring resumed resumed(a) 4.993808464 3,124,246 cpu-cycles 5.008597004 3,325,624 cpu-cycles 6.010387483 83,472,992 cpu-cycles 7.012266598 55,877,621 cpu-cycles 8.014175695 97,892,729 cpu-cycles 9.016056093 68,461,242 cpu-cycles 10.017937507 55,449,643 cpu-cycles 11.019830154 68,938,167 cpu-cycles 12.021719952 55,164,101 cpu-cycles 13.023627550 70,535,720 cpu-cycles 14.025580995 53,240,125 cpu-cycles paused(a) 14.997518260 53,558,068 cpu-cycles Monitoring paused 15.027216416 <not counted> cpu-cycles 16.029052729 <not counted> cpu-cycles 17.030904762 <not counted> cpu-cycles 18.032073424 <not counted> cpu-cycles 19.033805074 <not counted> cpu-cycles Monitoring resumed resumed(a) 20.001279097 3,021,022 cpu-cycles 20.035044381 6,434,367 cpu-cycles 21.036923813 89,358,251 cpu-cycles 22.038825169 72,516,351 cpu-cycles # time counts unit events 23.040715596 55,046,157 cpu-cycles 24.042643757 78,128,649 cpu-cycles 25.044558535 61,052,428 cpu-cycles 26.046452785 62,142,806 cpu-cycles 27.048353021 74,477,971 cpu-cycles 28.050241286 61,001,623 cpu-cycles 29.052149961 61,653,502 cpu-cycles paused(a) 30.004980264 82,729,640 cpu-cycles Monitoring paused 30.053516176 <not counted> cpu-cycles 31.055348366 <not counted> cpu-cycles 32.057202097 <not counted> cpu-cycles 33.059040702 <not counted> cpu-cycles 34.060843288 <not counted> cpu-cycles 35.000888624 <not counted> cpu-cycles [root@host acme]#
repo: git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git perf/core sha1: fe2413eefd7f21aade7eca7272332a1845c11837
[1] http://man7.org/linux/man-pages/man1/bash.1.html [2] http://man7.org/linux/man-pages/man2/pipe.2.html
--- Alexey Budankov (8): perf evlist: introduce control file descriptors perf evlist: implement control command handling functions perf stat: introduce control descriptors and --ctl-fd[-ack] options perf stat: implement resume and pause control commands handling perf docs: extend stat mode docs with info on --ctl-fd[-ack] options perf record: introduce control descriptors and --ctl-fd[-ack] options perf record: implement resume and pause control commands handling perf docs: extend record mode docs with info on --ctl-fd[-ack] options
tools/perf/Documentation/perf-record.txt | 37 ++++++ tools/perf/Documentation/perf-stat.txt | 38 +++++++ tools/perf/builtin-record.c | 39 ++++++- tools/perf/builtin-stat.c | 138 ++++++++++++++++------- tools/perf/builtin-trace.c | 2 +- tools/perf/util/evlist.c | 103 +++++++++++++++++ tools/perf/util/evlist.h | 18 +++ tools/perf/util/record.h | 4 +- tools/perf/util/stat.h | 4 +- 9 files changed, 335 insertions(+), 48 deletions(-)
| |