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Message-ID: <f7ef424f-da30-4bf4-3ffd-c1704ed06df0@linux.intel.com>
Date: Mon, 18 May 2020 11:08:43 +0300
From: Alexey Budankov <alexey.budankov@...ux.intel.com>
To: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Andi Kleen <ak@...ux.intel.com>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 0/9] perf: support enable and disable commands in stat
and record modes
Hi,
Is there anything else that could be done from my side to move this forward?
Thanks,
Alexey
On 13.05.2020 10:53, Alexey Budankov wrote:
>
> Changes in v3:
> - renamed functions and types from perf_evlist_ to evlist_ to avoid
> clash with libperf code;
> - extended commands to be strings of variable length consisting of
> command name and also possibly including command specific data;
> - merged docs update with the code changes;
> - updated docs for -D,--delay=-1 option for stat and record modes;
>
> v2: https://lore.kernel.org/lkml/d582cc3d-2302-c7e2-70d3-bc7ab6f628c3@linux.intel.com/
>
> Changes in v2:
> - renamed resume and pause commands to enable and disable ones, renamed
> CTL_CMD_RESUME and CTL_CMD_PAUSE to CTL_CMD_ENABLE and CTL_CMD_DISABLE
> to fit to the appropriate ioctls and avoid mixing up with PAUSE_OUTPUT
> ioctl;
> - factored out event handling loop into a handle_events() for stat mode;
> - separated -D,--delay=-1 into separate patches for stat and record modes;
>
> v1: https://lore.kernel.org/lkml/825a5132-b58d-c0b6-b050-5a6040386ec7@linux.intel.com/
>
> repo: tip of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git perf/core
>
> The patch set implements handling of 'start disabled', 'enable' and 'disable'
> external control commands which can be provided for stat and record modes
> of the tool from an external controlling process. 'start disabled' command
> can be used to postpone enabling of events in the beginning of a monitoring
> session. 'enable' and 'disable' commands can be used to enable and disable
> events correspondingly any time after the start of the session.
>
> The 'start disabled', 'enable' and 'disable' 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 disabled' 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 control commands and reply
> to the controlling process on the completion of received commands.
>
> The tool reads control command message from ctl-fd descriptor, handles the
> command and optionally replies acknowledgement message to fd-ack descriptor,
> if it is specified on the command line. 'enable' command is recognized as
> 'enable' string message and 'disable' command is recognized as 'disable'
> string message both received from ctl-fd descriptor. Completion message is
> 'ack\n' and sent to fd-ack descriptor.
>
> Example 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 '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})"
> sleep 5 && echo 'enable' >&${ctl_fd} && read -u ${ctl_fd_ack} e2 && echo "enabled(${e2})"
> sleep 10 && echo 'disable' >&${ctl_fd} && read -u ${ctl_fd_ack} d2 && echo "disabled(${d2})"
>
> exec {ctl_fd_ack}>&- && unlink ${ctl_ack_fifo}
> exec {ctl_fd}>&- && unlink ${ctl_fifo}
>
> wait -n ${perf_pid}
> exit $?
>
>
> Script output:
>
> [root@...t dir] example
> Events disabled
> # 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
> Events enabled
> enabled(ack)
> 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
> disabled(ack)
> 14.997518260 53,558,068 cpu-cycles
> Events disabled
> 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
> Events enabled
> enabled(ack)
> 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
> disabled(ack)
> 30.004980264 82,729,640 cpu-cycles
> Events disabled
> 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@...t dir]#
>
> [1] http://man7.org/linux/man-pages/man1/bash.1.html
> [2] http://man7.org/linux/man-pages/man2/pipe.2.html
>
> ---
> Alexey Budankov (9):
> perf evlist: introduce control file descriptors
> perf evlist: implement control command handling functions
> perf stat: factor out event handling loop into a function
> perf stat: extend -D,--delay option with -1 value
> perf stat: implement control commands handling
> perf stat: introduce --ctl-fd[-ack] options
> perf record: extend -D,--delay option with -1 value
> perf record: implement control commands handling
> perf record: introduce --ctl-fd[-ack] options
>
> tools/perf/Documentation/perf-record.txt | 44 +++++++-
> tools/perf/Documentation/perf-stat.txt | 45 +++++++-
> tools/perf/builtin-record.c | 39 ++++++-
> tools/perf/builtin-stat.c | 137 ++++++++++++++++-------
> tools/perf/builtin-trace.c | 2 +-
> tools/perf/util/evlist.c | 131 ++++++++++++++++++++++
> tools/perf/util/evlist.h | 24 ++++
> tools/perf/util/record.h | 4 +-
> tools/perf/util/stat.h | 4 +-
> 9 files changed, 379 insertions(+), 51 deletions(-)
>
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