Re: [PATCH v8 0/6] perf record: Track sideband events for all CPUs when tracing selected CPUs

[Arnaldo Carvalho de Melo]

Em Mon, Sep 04, 2023 at 02:33:34AM +0000, Yang Jihong escreveu:
> User space tasks can migrate between CPUs, track sideband events for all
> CPUs.
> 
> The specific scenarios are as follows:
> 
>          CPU0                                 CPU1
>   perf record -C 0 start
>                               taskA starts to be created and executed
>                                 -> PERF_RECORD_COMM and PERF_RECORD_MMAP
>                                    events only deliver to CPU1
>                               ......
>                                 |
>                           migrate to CPU0
>                                 |
>   Running on CPU0    <----------/
>   ...
> 
>   perf record -C 0 stop
> 
> Now perf samples the PC of taskA. However, perf does not record the
> PERF_RECORD_COMM and PERF_RECORD_COMM events of taskA.
> Therefore, the comm and symbols of taskA cannot be parsed.
> 
> The sys_perf_event_open invoked is as follows:
> 
>   # perf --debug verbose=3 record -e cpu-clock -C 1 true
>   <SNIP>
>   Opening: cpu-clock
>   ------------------------------------------------------------
>   perf_event_attr:
>     type                             1 (PERF_TYPE_SOFTWARE)
>     size                             136
>     config                           0 (PERF_COUNT_SW_CPU_CLOCK)
>     { sample_period, sample_freq }   4000
>     sample_type                      IP|TID|TIME|CPU|PERIOD|IDENTIFIER
>     read_format                      ID|LOST
>     disabled                         1
>     inherit                          1
>     freq                             1
>     sample_id_all                    1
>     exclude_guest                    1
>   ------------------------------------------------------------
>   sys_perf_event_open: pid -1  cpu 1  group_fd -1  flags 0x8 = 5
>   Opening: dummy:u
>   ------------------------------------------------------------
>   perf_event_attr:
>     type                             1 (PERF_TYPE_SOFTWARE)
>     size                             136
>     config                           0x9 (PERF_COUNT_SW_DUMMY)
>     { sample_period, sample_freq }   1
>     sample_type                      IP|TID|TIME|CPU|IDENTIFIER
>     read_format                      ID|LOST
>     inherit                          1
>     exclude_kernel                   1
>     exclude_hv                       1
>     mmap                             1
>     comm                             1
>     task                             1
>     sample_id_all                    1
>     exclude_guest                    1
>     mmap2                            1
>     comm_exec                        1
>     ksymbol                          1
>     bpf_event                        1
>   ------------------------------------------------------------
>   sys_perf_event_open: pid -1  cpu 0  group_fd -1  flags 0x8 = 6
>   sys_perf_event_open: pid -1  cpu 1  group_fd -1  flags 0x8 = 7
>   sys_perf_event_open: pid -1  cpu 2  group_fd -1  flags 0x8 = 9
>   sys_perf_event_open: pid -1  cpu 3  group_fd -1  flags 0x8 = 10
>   sys_perf_event_open: pid -1  cpu 4  group_fd -1  flags 0x8 = 11
>   sys_perf_event_open: pid -1  cpu 5  group_fd -1  flags 0x8 = 12
>   sys_perf_event_open: pid -1  cpu 6  group_fd -1  flags 0x8 = 13
>   sys_perf_event_open: pid -1  cpu 7  group_fd -1  flags 0x8 = 14
>   <SNIP>
> 
> Changes since_v7:
>  - The condition for requiring system_wide sideband is changed to
>    "as long as a non-dummy event exists" (patch4).
>  - Modify the corresponding test case to record only dummy event (patch6).
>  - Thanks to tested-by tag from Ravi, but because the solution is modified,
>    the tested-by tag of Ravi is not added to this version.
> 
> Changes since_v6:
>  - Patch1:
>     1. No change.
>     2. Keep Acked-by tag from Adrian.
>  - Patch2:
>     1. Update commit message as suggested by Ian.
>     2. Keep Acked-by tag from Adrian because code is not modified.
>  - Patch3:
>     1. Update comment as suggested by Ian.
>     2. Merge original patch5 ("perf test: Update base-record & system-wide-dummy attr") as suggested by Ian.
>     3. Only merge commit, keep Acked-by tag from Adrian.
>  - Patch4:
>     1. No change. Because Adrian recommends not changing the function name.
>     2. Keep Acked-by tag from Adrian.
>  - Patch5:
>     1. Add cleanup on trap function as suggested by Ian.
>     2. Remove Tested-by tag from Adrian because the script is modified.
>  - Patch6:
>     1. Add Reviewed-by tag from Ian.

I'm in doubt about these Acked-by/Reviewed-by tags, do they still stand? They are
not in the latest series, can you please check?

- Arnaldo
 
> Changes since_v5:
>  - No code changes.
>  - Detailed commit message of patch3.
>  - Add Acked-by and Tested-by tags from Adrian Hunter.
> 
> Changes since_v4:
>  - Simplify check code for record__tracking_system_wide().
>  - Add perf attr test result to commit message for patch 7.
> 
> Changes since_v3:
>  - Check fall_kernel, all_user, and dummy or exclude_user when determining
>    whether system wide is required.
> 
> Changes since_v2:
>  - Rename record_tracking.sh to record_sideband.sh in tools/perf/tests/shell.
>  - Remove "perf evlist: Skip dummy event sample_type check for evlist_config" patch.
>  - Add opts->all_kernel check in record__config_tracking_events().
>  - Add perf_event_attr test for record selected CPUs exclude_user.
>  - Update base-record & system-wide-dummy sample_type attr expected values for test-record-C0.
> 
> Changes since v1:
>  - Add perf_evlist__go_system_wide() via internal/evlist.h instead of
>    exporting perf_evlist__propagate_maps().
>  - Use evlist__add_aux_dummy() instead of evlist__add_dummy() in
>    evlist__findnew_tracking_event().
>  - Add a parameter in evlist__findnew_tracking_event() to deal with
>    system_wide inside.
>  - Add sideband for all CPUs when tracing selected CPUs comments on
>    the perf record man page.
>  - Use "sideband events" instead of "tracking events".
>  - Adjust the patches Sequence.
>  - Add patch5 to skip dummy event sample_type check for evlist_config.
>  - Add patch6 to update system-wide-dummy attr values for perf test.
> 
> Yang Jihong (6):
>   perf evlist: Add perf_evlist__go_system_wide() helper
>   perf evlist: Add evlist__findnew_tracking_event() helper
>   perf record: Move setting tracking events before
>     record__init_thread_masks()
>   perf record: Track sideband events for all CPUs when tracing selected
>     CPUs
>   perf test: Add test case for record sideband events
>   perf test: Add perf_event_attr test for record selected CPUs
>     exclude_user
> 
> Yang Jihong (6):
>   perf evlist: Add perf_evlist__go_system_wide() helper
>   perf evlist: Add evlist__findnew_tracking_event() helper
>   perf record: Move setting tracking events before
>     record__init_thread_masks()
>   perf record: Track sideband events for all CPUs when tracing selected
>     CPUs
>   perf test: Add test case for record sideband events
>   perf test: Add perf_event_attr test for record dummy event
> 
>  tools/lib/perf/evlist.c                    |  9 +++
>  tools/lib/perf/include/internal/evlist.h   |  2 +
>  tools/perf/Documentation/perf-record.txt   |  3 +
>  tools/perf/builtin-record.c                | 92 +++++++++++++++-------
>  tools/perf/tests/attr/system-wide-dummy    | 14 ++--
>  tools/perf/tests/attr/test-record-C0       |  4 +-
>  tools/perf/tests/attr/test-record-dummy-C0 | 55 +++++++++++++
>  tools/perf/tests/shell/record_sideband.sh  | 58 ++++++++++++++
>  tools/perf/util/evlist.c                   | 18 +++++
>  tools/perf/util/evlist.h                   |  1 +
>  10 files changed, 221 insertions(+), 35 deletions(-)
>  create mode 100644 tools/perf/tests/attr/test-record-dummy-C0
>  create mode 100755 tools/perf/tests/shell/record_sideband.sh
> 
> -- 
> 2.30.GIT
> 

-- 

- Arnaldo