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Message-ID: <ZPij6XjhdUW3nIqU@kernel.org>
Date: Wed, 6 Sep 2023 13:08:09 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Yang Jihong <yangjihong1@...wei.com>
Cc: peterz@...radead.org, mingo@...hat.com, mark.rutland@....com,
alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
namhyung@...nel.org, irogers@...gle.com, adrian.hunter@...el.com,
kan.liang@...ux.intel.com, james.clark@....com,
tmricht@...ux.ibm.com, ak@...ux.intel.com,
anshuman.khandual@....com, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v8 0/6] perf record: Track sideband events for all CPUs
when tracing selected CPUs
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
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