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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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