perf record: Track sideband events for all CPUs when tracing selected CPUs
authorYang Jihong <yangjihong1@huawei.com>
Mon, 4 Sep 2023 02:33:38 +0000 (02:33 +0000)
committerArnaldo Carvalho de Melo <acme@redhat.com>
Tue, 12 Sep 2023 20:31:43 +0000 (17:31 -0300)
commit74b4f3ecdf64b62446abfb36669b3d40a42d34eb
tree839980cf12d361618f7a602c4274c4ad61432e73
parent1285ab300d598ead593b190af65a16f4b0843c68
perf record: Track sideband events for all CPUs when tracing selected CPUs

User space tasks can migrate between CPUs, we need to track side-band
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_MMAP events of taskA.
Therefore, the comm and symbols of taskA cannot be parsed.

The solution is to record sideband events for all CPUs when tracing
selected CPUs. Because this modifies the default behavior, add related
comments to the perf record man page.

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>

Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Tested-by: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Link: https://lore.kernel.org/r/20230904023340.12707-5-yangjihong1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
tools/perf/Documentation/perf-record.txt
tools/perf/builtin-record.c