Messages in this thread Patch in this message | | | Date | Wed, 22 Apr 2020 10:36:15 -0700 | Subject | [PATCH v3] perf record: add dummy event during system wide synthesis | From | Ian Rogers <> |
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During the processing of /proc during event synthesis new processes may start. Add a dummy event if /proc is to be processed, to capture mmaps for starting processes. This reuses the existing logic for initial-delay.
v3 fixes the attr test of test-record-C0 v2 fixes the dummy event configuration and a branch stack issue.
Suggested-by: Stephane Eranian <eranian@google.com> Signed-off-by: Ian Rogers <irogers@google.com> --- tools/perf/builtin-record.c | 19 +++++++--- tools/perf/tests/attr/system-wide-dummy | 50 +++++++++++++++++++++++++ tools/perf/tests/attr/test-record-C0 | 12 +++++- tools/perf/util/evsel.c | 5 ++- 4 files changed, 78 insertions(+), 8 deletions(-) create mode 100644 tools/perf/tests/attr/system-wide-dummy
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 1ab349abe904..8d1e93351298 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -805,19 +805,28 @@ static int record__open(struct record *rec) int rc = 0; /* - * For initial_delay we need to add a dummy event so that we can track - * PERF_RECORD_MMAP while we wait for the initial delay to enable the - * real events, the ones asked by the user. + * For initial_delay or system wide, we need to add a dummy event so + * that we can track PERF_RECORD_MMAP to cover the delay of waiting or + * event synthesis. */ - if (opts->initial_delay) { + if (opts->initial_delay || target__has_cpu(&opts->target)) { if (perf_evlist__add_dummy(evlist)) return -ENOMEM; + /* Disable tracking of mmaps on lead event. */ pos = evlist__first(evlist); pos->tracking = 0; + /* Set up dummy event. */ pos = evlist__last(evlist); pos->tracking = 1; - pos->core.attr.enable_on_exec = 1; + /* + * Enable the dummy event when the process is forked for + * initial_delay, immediately for system wide. + */ + if (opts->initial_delay) + pos->core.attr.enable_on_exec = 1; + else + pos->immediate = 1; } perf_evlist__config(evlist, opts, &callchain_param); diff --git a/tools/perf/tests/attr/system-wide-dummy b/tools/perf/tests/attr/system-wide-dummy new file mode 100644 index 000000000000..eba723cc0d38 --- /dev/null +++ b/tools/perf/tests/attr/system-wide-dummy @@ -0,0 +1,50 @@ +# Event added by system-wide or CPU perf-record to handle the race of +# processes starting while /proc is processed. +[event] +fd=1 +group_fd=-1 +cpu=* +pid=-1 +flags=8 +type=1 +size=120 +config=9 +sample_period=4000 +sample_type=455 +read_format=4 +# Event will be enabled right away. +disabled=0 +inherit=1 +pinned=0 +exclusive=0 +exclude_user=0 +exclude_kernel=0 +exclude_hv=0 +exclude_idle=0 +mmap=1 +comm=1 +freq=1 +inherit_stat=0 +enable_on_exec=0 +task=1 +watermark=0 +precise_ip=0 +mmap_data=0 +sample_id_all=1 +exclude_host=0 +exclude_guest=0 +exclude_callchain_kernel=0 +exclude_callchain_user=0 +mmap2=1 +comm_exec=1 +context_switch=0 +write_backward=0 +namespaces=0 +use_clockid=0 +wakeup_events=0 +bp_type=0 +config1=0 +config2=0 +branch_sample_type=0 +sample_regs_user=0 +sample_stack_user=0 diff --git a/tools/perf/tests/attr/test-record-C0 b/tools/perf/tests/attr/test-record-C0 index 93818054ae20..317730b906dd 100644 --- a/tools/perf/tests/attr/test-record-C0 +++ b/tools/perf/tests/attr/test-record-C0 @@ -9,6 +9,14 @@ cpu=0 # no enable on exec for CPU attached enable_on_exec=0 -# PERF_SAMPLE_IP | PERF_SAMPLE_TID PERF_SAMPLE_TIME | # PERF_SAMPLE_PERIOD +# PERF_SAMPLE_IP | PERF_SAMPLE_TID | PERF_SAMPLE_TIME | +# PERF_SAMPLE_ID | PERF_SAMPLE_PERIOD # + PERF_SAMPLE_CPU added by -C 0 -sample_type=391 +sample_type=455 + +# Dummy event handles mmaps, comm and task. +mmap=0 +comm=0 +task=0 + +[event:system-wide-dummy] diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 6a571d322bb2..ca8f9533d8f9 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1163,11 +1163,14 @@ void perf_evsel__config(struct evsel *evsel, struct record_opts *opts, } /* + * A dummy event never triggers any actual counter and therefore + * cannot be used with branch_stack. + * * For initial_delay, a dummy event is added implicitly. * The software event will trigger -EOPNOTSUPP error out, * if BRANCH_STACK bit is set. */ - if (opts->initial_delay && is_dummy_event(evsel)) + if (is_dummy_event(evsel)) perf_evsel__reset_sample_bit(evsel, BRANCH_STACK); } -- 2.26.2.303.gf8c07b1a785-goog
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