Re: [PATCH v5 00/13] perf: support enable and disable commands in stat and record modes

Alexey Budankov
2020-06-01T20:21:11Z

Please see v6 with all improvements.

~Alexey

On 01.06.2020 19:53, Alexey Budankov wrote:
>
> Please refrain from testing this patch set. For some reason it lacks exposure
> of ctl-fd, ctl-fd-ack options. There are also functional issues. I am working
> to improve all that and resend fixed v5.
>
> ~Alexey
>
> On 01.06.2020 18:46, Alexey Budankov wrote:
>>
>> Changes in v5:
>> - split re-factoring of events handling loops for stat mode
>> into smaller incremental parts
>>
>> v4: https://lore.kernel.org/lkml/653fe5f3-c986-a841-1ed8-0a7d2fa24c00@linux.intel.com/
>>
>> 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@linux.intel.com/
>>
>> 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@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 (13):
>> tools/libperf: introduce static poll file descriptors
>> perf evlist: introduce control file descriptors
>> perf evlist: implement control command handling functions
>> perf stat: factor out body of event handling loop for system wide
>> perf stat: move target check to loop control statement
>> perf stat: factor out body of event handling loop for launch case
>> perf stat: factor out event handling loop into dispatch_events()
>> 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 | 5 +-
>> tools/perf/Documentation/perf-stat.txt | 45 ++++++-
>> tools/perf/builtin-record.c | 34 +++++-
>> tools/perf/builtin-stat.c | 145 +++++++++++++++++------
>> 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, 407 insertions(+), 50 deletions(-)
>>