From 2fda5ada07f36f6cde39a52e7f05d86ea8ffdc33 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Fri, 19 Oct 2018 15:47:34 -0300 Subject: 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 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 @ 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 Cc: David Ahern Cc: Jiri Olsa Cc: Milian Wolff Cc: Namhyung Kim Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-og00yasj276joem6e14l1eas@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/parse-events.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'tools/perf/util/parse-events.c') diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c index f8cd3e7c9186..59be3466d64d 100644 --- a/tools/perf/util/parse-events.c +++ b/tools/perf/util/parse-events.c @@ -926,6 +926,7 @@ static const char *config_term_names[__PARSE_EVENTS__TERM_TYPE_NR] = { [PARSE_EVENTS__TERM_TYPE_NOINHERIT] = "no-inherit", [PARSE_EVENTS__TERM_TYPE_INHERIT] = "inherit", [PARSE_EVENTS__TERM_TYPE_MAX_STACK] = "max-stack", + [PARSE_EVENTS__TERM_TYPE_MAX_EVENTS] = "nr", [PARSE_EVENTS__TERM_TYPE_OVERWRITE] = "overwrite", [PARSE_EVENTS__TERM_TYPE_NOOVERWRITE] = "no-overwrite", [PARSE_EVENTS__TERM_TYPE_DRV_CFG] = "driver-config", @@ -1037,6 +1038,9 @@ do { \ case PARSE_EVENTS__TERM_TYPE_MAX_STACK: CHECK_TYPE_VAL(NUM); break; + case PARSE_EVENTS__TERM_TYPE_MAX_EVENTS: + CHECK_TYPE_VAL(NUM); + break; default: err->str = strdup("unknown term"); err->idx = term->err_term; @@ -1084,6 +1088,7 @@ static int config_term_tracepoint(struct perf_event_attr *attr, case PARSE_EVENTS__TERM_TYPE_INHERIT: case PARSE_EVENTS__TERM_TYPE_NOINHERIT: case PARSE_EVENTS__TERM_TYPE_MAX_STACK: + case PARSE_EVENTS__TERM_TYPE_MAX_EVENTS: case PARSE_EVENTS__TERM_TYPE_OVERWRITE: case PARSE_EVENTS__TERM_TYPE_NOOVERWRITE: return config_term_common(attr, term, err); @@ -1162,6 +1167,9 @@ do { \ case PARSE_EVENTS__TERM_TYPE_MAX_STACK: ADD_CONFIG_TERM(MAX_STACK, max_stack, term->val.num); break; + case PARSE_EVENTS__TERM_TYPE_MAX_EVENTS: + ADD_CONFIG_TERM(MAX_EVENTS, max_events, term->val.num); + break; case PARSE_EVENTS__TERM_TYPE_OVERWRITE: ADD_CONFIG_TERM(OVERWRITE, overwrite, term->val.num ? 1 : 0); break; -- cgit