Re: [PATCH v4 00/10] perf: support enable and disable commands in stat and record modes

From: Jiri Olsa
Date: Wed May 27 2020 - 06:30:18 EST

On Wed, May 27, 2020 at 12:27:31PM +0300, Alexey Budankov wrote:
>
> Making sure it is not sneaked out of your attention.

yep, I know about it, will get to it this week

jirka

>
> 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(-)
> >
>