Re: [PATCH v4 00/10] perf: support enable and disable commands in stat and record modes
From: Alexey Budankov
Date: Wed May 27 2020 - 05:27:52 EST
Making sure it is not sneaked out of your attention.
Thanks,
Alexey
On 25.05.2020 17:11, Alexey Budankov wrote:
>
> Changes in v4:
> - made checking of ctlfd state unconditional in record trace streaming loop
> - introduced static poll fds to keep evlist__filter_pollfd() unaffected
> - handled ret code of evlist__initialize_ctlfd() where need
> - renamed and structured handle_events() function
> - applied anonymous structs where needed
>
> v3: https://lore.kernel.org/lkml/eb38e9e5-754f-d410-1d9b-e26b702d51b7@xxxxxxxxxxxxxxx/
>
> 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@xxxxxxxxxxxxxxx/
>
> 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@xxxxxxxxxxxxxxx/
>
> 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@host 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@host 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 (10):
> tools/libperf: introduce static poll file descriptors
> 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/lib/api/fd/array.c | 42 +++++-
> tools/lib/api/fd/array.h | 7 +
> tools/lib/perf/evlist.c | 11 ++
> tools/lib/perf/include/internal/evlist.h | 2 +
> tools/perf/Documentation/perf-record.txt | 44 ++++++-
> tools/perf/Documentation/perf-stat.txt | 45 ++++++-
> tools/perf/builtin-record.c | 38 +++++-
> tools/perf/builtin-stat.c | 155 +++++++++++++++++------
> tools/perf/builtin-trace.c | 2 +-
> tools/perf/util/evlist.c | 131 +++++++++++++++++++
> tools/perf/util/evlist.h | 25 ++++
> tools/perf/util/record.h | 4 +-
> tools/perf/util/stat.h | 4 +-
> 13 files changed, 459 insertions(+), 51 deletions(-)
>