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author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-10-19 15:47:34 -0300 |
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committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-10-19 16:31:09 -0300 |
commit | 2fda5ada07f36f6cde39a52e7f05d86ea8ffdc33 (patch) | |
tree | d5692dada50340add7eb8a717a38a044b46c7b39 /tools/perf/util/evsel.c | |
parent | 5067a8cdd4ce3588fca2e0ee554f0f081650de8f (diff) |
perf evsel: Introduce per event max_events property
This simply adds the field to 'struct perf_evsel' and allows setting
it via the event parser, to test it lets trace trace:
First look at where in a function that receives an evsel we can put a probe
to read how evsel->max_events was setup:
# perf probe -x ~/bin/perf -L trace__event_handler
<trace__event_handler@/home/acme/git/perf/tools/perf/builtin-trace.c:0>
0 static int trace__event_handler(struct trace *trace, struct perf_evsel *evsel,
union perf_event *event __maybe_unused,
struct perf_sample *sample)
3 {
4 struct thread *thread = machine__findnew_thread(trace->host, sample->pid, sample->tid);
5 int callchain_ret = 0;
7 if (sample->callchain) {
8 callchain_ret = trace__resolve_callchain(trace, evsel, sample, &callchain_cursor);
9 if (callchain_ret == 0) {
10 if (callchain_cursor.nr < trace->min_stack)
11 goto out;
12 callchain_ret = 1;
}
}
See what variables we can probe at line 7:
# perf probe -x ~/bin/perf -V trace__event_handler:7
Available variables at trace__event_handler:7
@<trace__event_handler+89>
int callchain_ret
struct perf_evsel* evsel
struct perf_sample* sample
struct thread* thread
struct trace* trace
union perf_event* event
Add a probe at that line asking for evsel->max_events to be collected and named
as "max_events":
# perf probe -x ~/bin/perf trace__event_handler:7 'max_events=evsel->max_events'
Added new event:
probe_perf:trace__event_handler (on trace__event_handler:7 in /home/acme/bin/perf with max_events=evsel->max_events)
You can now use it in all perf tools, such as:
perf record -e probe_perf:trace__event_handler -aR sleep 1
Now use 'perf trace', here aliased to just 'trace' and trace trace, i.e.
the first 'trace' is tracing just that 'probe_perf:trace__event_handler' event,
while the traced trace is tracing all scheduler tracepoints, will stop at two
events (--max-events 2) and will just set evsel->max_events for all the sched
tracepoints to 9, we will see the output of both traces intermixed:
# trace -e *perf:*event_handler trace --max-events 2 -e sched:*/nr=9/
0.000 :0/0 sched:sched_waking:comm=rcu_sched pid=10 prio=120 target_cpu=000
0.009 :0/0 sched:sched_wakeup:comm=rcu_sched pid=10 prio=120 target_cpu=000
0.000 trace/23949 probe_perf:trace__event_handler:(48c34a) max_events=0x9
0.046 trace/23949 probe_perf:trace__event_handler:(48c34a) max_events=0x9
#
Now, if the traced trace sends its output to /dev/null, we'll see just
what the first level trace outputs: that evsel->max_events is indeed
being set to 9:
# trace -e *perf:*event_handler trace -o /dev/null --max-events 2 -e sched:*/nr=9/
0.000 trace/23961 probe_perf:trace__event_handler:(48c34a) max_events=0x9
0.030 trace/23961 probe_perf:trace__event_handler:(48c34a) max_events=0x9
#
Now that we can set evsel->max_events, we can go to the next step, honour that
per-event property in 'perf trace'.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-og00yasj276joem6e14l1eas@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/evsel.c')
-rw-r--r-- | tools/perf/util/evsel.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 29d7b97f66fb..7e95ec1c19a8 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -232,6 +232,7 @@ void perf_evsel__init(struct perf_evsel *evsel, evsel->leader = evsel; evsel->unit = ""; evsel->scale = 1.0; + evsel->max_events = ULONG_MAX; evsel->evlist = NULL; evsel->bpf_fd = -1; INIT_LIST_HEAD(&evsel->node); @@ -793,6 +794,9 @@ static void apply_config_terms(struct perf_evsel *evsel, case PERF_EVSEL__CONFIG_TERM_MAX_STACK: max_stack = term->val.max_stack; break; + case PERF_EVSEL__CONFIG_TERM_MAX_EVENTS: + evsel->max_events = term->val.max_events; + break; case PERF_EVSEL__CONFIG_TERM_INHERIT: /* * attr->inherit should has already been set by |