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perf tools: Add support for leader-sampling with AUX area events

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When AUX area events are used in sampling mode, they must be the group
leader, but the group leader is also used for leader-sampling. However,
it is not desirable to use an AUX area event as the leader for
leader-sampling, because it doesn't have any samples of its own. To support
leader-sampling with AUX area events, use the 2nd event of the group as the
"leader" for the purposes of leader-sampling.

Example:

 # perf record --kcore --aux-sample -e '{intel_pt//,cycles,instructions}:S' -c 10000 uname
 [ perf record: Woken up 3 times to write data ]
 [ perf record: Captured and wrote 0.786 MB perf.data ]
 # perf report
 Samples: 380  of events 'anon group { cycles, instructions }', Event count (approx.): 3026164
           Children              Self  Command  Shared Object      Symbol
 +   38.76%  42.65%     0.00%   0.00%  uname    [kernel.kallsyms]  [k] __x86_indirect_thunk_rax
 +   35.82%  31.33%     0.00%   0.00%  uname    ld-2.28.so         [.] _dl_start_user
 +   34.29%  29.74%     0.55%   0.47%  uname    ld-2.28.so         [.] _dl_start
 +   33.73%  28.62%     1.60%   0.97%  uname    ld-2.28.so         [.] dl_main
 +   33.19%  29.04%     0.52%   0.32%  uname    ld-2.28.so         [.] _dl_sysdep_start
 +   27.83%  33.74%     0.00%   0.00%  uname    [kernel.kallsyms]  [k] do_syscall_64
 +   26.76%  33.29%     0.00%   0.00%  uname    [kernel.kallsyms]  [k] entry_SYSCALL_64_after_hwframe
 +   23.78%  20.33%     5.97%   5.25%  uname    [kernel.kallsyms]  [k] page_fault
 +   23.18%  24.60%     0.00%   0.00%  uname    libc-2.28.so       [.] __libc_start_main
 +   22.64%  24.37%     0.00%   0.00%  uname    uname              [.] _start
 +   21.04%  23.27%     0.00%   0.00%  uname    uname              [.] main
 +   19.48%  18.08%     3.72%   3.64%  uname    ld-2.28.so         [.] _dl_relocate_object
 +   19.47%  21.81%     0.00%   0.00%  uname    libc-2.28.so       [.] setlocale
 +   19.44%  21.56%     0.52%   0.61%  uname    libc-2.28.so       [.] _nl_find_locale
 +   17.87%  19.66%     0.00%   0.00%  uname    libc-2.28.so       [.] _nl_load_locale_from_archive
 +   15.71%  13.73%     0.53%   0.52%  uname    [kernel.kallsyms]  [k] do_page_fault
 +   15.18%  13.21%     1.03%   0.68%  uname    [kernel.kallsyms]  [k] handle_mm_fault
 +   14.15%  12.53%     1.01%   1.12%  uname    [kernel.kallsyms]  [k] __handle_mm_fault
 +   12.03%   9.67%     0.54%   0.32%  uname    ld-2.28.so         [.] _dl_map_object
 +   10.55%   8.48%     0.00%   0.00%  uname    ld-2.28.so         [.] openaux
 +   10.55%  20.20%     0.52%   0.61%  uname    libc-2.28.so       [.] __run_exit_handlers

Comnmitter notes:

Fixed up this problem:

  util/record.c: In function ‘perf_evlist__config’:
  util/record.c:256:3: error: too few arguments to function ‘perf_evsel__config_leader_sampling’
    256 |   perf_evsel__config_leader_sampling(evsel);
        |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  util/record.c:190:13: note: declared here
    190 | static void perf_evsel__config_leader_sampling(struct evsel *evsel,
        |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-17-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Adrian Hunter 2020-04-01 13:16:13 +03:00 committed by Arnaldo Carvalho de Melo
parent 94d3820f2e
commit e345997914
2 changed files with 42 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
tools/perf/Documentation/perf-list.txt
View File

@ -258,6 +258,9 @@ Normally all events in an event group sample, but with :S only
the first event (the leader) samples, and it only reads the values of the
other events in the group.
However, in the case AUX area events (e.g. Intel PT or CoreSight), the AUX
area event must be the leader, so then the second event samples, not the first.
OPTIONS
-------

45
tools/perf/util/record.c
View File

@ -167,17 +167,46 @@ bool perf_can_aux_sample(void)
return true;
}
static void perf_evsel__config_leader_sampling(struct evsel *evsel)
/*
* perf_evsel__config_leader_sampling() uses special rules for leader sampling.
* However, if the leader is an AUX area event, then assume the event to sample
* is the next event.
*/
static struct evsel *perf_evsel__read_sampler(struct evsel *evsel,
struct evlist *evlist)
{
struct evsel *leader = evsel->leader;
if (perf_evsel__is_aux_event(leader)) {
evlist__for_each_entry(evlist, evsel) {
if (evsel->leader == leader && evsel != evsel->leader)
return evsel;
}
}
return leader;
}
static void perf_evsel__config_leader_sampling(struct evsel *evsel,
struct evlist *evlist)
{
struct perf_event_attr *attr = &evsel->core.attr;
struct evsel *leader = evsel->leader;
struct evsel *read_sampler;
if (leader == evsel || !leader->sample_read)
if (!leader->sample_read)
return;
read_sampler = perf_evsel__read_sampler(evsel, evlist);
if (evsel == read_sampler)
return;
/*
* Disable sampling for all group members other
* than leader in case leader 'leads' the sampling.
* Disable sampling for all group members other than the leader in
* case the leader 'leads' the sampling, except when the leader is an
* AUX area event, in which case the 2nd event in the group is the one
* that 'leads' the sampling.
*/
attr->freq = 0;
attr->sample_freq = 0;
@ -188,8 +217,12 @@ static void perf_evsel__config_leader_sampling(struct evsel *evsel)
* We don't get a sample for slave events, we make them when delivering
* the group leader sample. Set the slave event to follow the master
* sample_type to ease up reporting.
* An AUX area event also has sample_type requirements, so also include
* the sample type bits from the leader's sample_type to cover that
* case.
*/
attr->sample_type = leader->core.attr.sample_type;
attr->sample_type = read_sampler->core.attr.sample_type |
leader->core.attr.sample_type;
}
void perf_evlist__config(struct evlist *evlist, struct record_opts *opts,
@ -220,7 +253,7 @@ void perf_evlist__config(struct evlist *evlist, struct record_opts *opts,
/* Configure leader sampling here now that the sample type is known */
evlist__for_each_entry(evlist, evsel)
perf_evsel__config_leader_sampling(evsel);
perf_evsel__config_leader_sampling(evsel, evlist);
if (opts->full_auxtrace) {
/*