perf evlist: Add 'system_wide' option

Add an option to cause a selected event to be opened always without a
pid when configured by perf_evsel__config().

This is needed when using the sched_switch tracepoint to follow object
code execution.

sched_switch occurs before the task switch and so it cannot record it in
a context limited to that task.  Note that also means that sched_switch
is useless when capturing data per-thread, as is the 'context-switches'
software event for the same reason.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1406786474-9306-9-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 26 insertions, 5 deletions

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 0c8919decac8..66de9a708163 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -695,6 +695,10 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts)
 int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
 {
 	int cpu, thread;
+
+	if (evsel->system_wide)
+		nthreads = 1;
+
 	evsel->fd = xyarray__new(ncpus, nthreads, sizeof(int));
 
 	if (evsel->fd) {
@@ -713,6 +717,9 @@ static int perf_evsel__run_ioctl(struct perf_evsel *evsel, int ncpus, int nthrea
 {
 	int cpu, thread;
 
+	if (evsel->system_wide)
+		nthreads = 1;
+
 	for (cpu = 0; cpu < ncpus; cpu++) {
 		for (thread = 0; thread < nthreads; thread++) {
 			int fd = FD(evsel, cpu, thread),
@@ -743,6 +750,9 @@ int perf_evsel__enable(struct perf_evsel *evsel, int ncpus, int nthreads)
 
 int perf_evsel__alloc_id(struct perf_evsel *evsel, int ncpus, int nthreads)
 {
+	if (evsel->system_wide)
+		nthreads = 1;
+
 	evsel->sample_id = xyarray__new(ncpus, nthreads, sizeof(struct perf_sample_id));
 	if (evsel->sample_id == NULL)
 		return -ENOMEM;
@@ -787,6 +797,9 @@ void perf_evsel__close_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
 {
 	int cpu, thread;
 
+	if (evsel->system_wide)
+		nthreads = 1;
+
 	for (cpu = 0; cpu < ncpus; cpu++)
 		for (thread = 0; thread < nthreads; ++thread) {
 			close(FD(evsel, cpu, thread));
@@ -875,6 +888,9 @@ int __perf_evsel__read(struct perf_evsel *evsel,
 	int cpu, thread;
 	struct perf_counts_values *aggr = &evsel->counts->aggr, count;
 
+	if (evsel->system_wide)
+		nthreads = 1;
+
 	aggr->val = aggr->ena = aggr->run = 0;
 
 	for (cpu = 0; cpu < ncpus; cpu++) {
@@ -997,13 +1013,18 @@ static size_t perf_event_attr__fprintf(struct perf_event_attr *attr, FILE *fp)
 static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
 			      struct thread_map *threads)
 {
-	int cpu, thread;
+	int cpu, thread, nthreads;
 	unsigned long flags = PERF_FLAG_FD_CLOEXEC;
 	int pid = -1, err;
 	enum { NO_CHANGE, SET_TO_MAX, INCREASED_MAX } set_rlimit = NO_CHANGE;
 
+	if (evsel->system_wide)
+		nthreads = 1;
+	else
+		nthreads = threads->nr;
+
 	if (evsel->fd == NULL &&
-	    perf_evsel__alloc_fd(evsel, cpus->nr, threads->nr) < 0)
+	    perf_evsel__alloc_fd(evsel, cpus->nr, nthreads) < 0)
 		return -ENOMEM;
 
 	if (evsel->cgrp) {
@@ -1027,10 +1048,10 @@ retry_sample_id:
 
 	for (cpu = 0; cpu < cpus->nr; cpu++) {
 
-		for (thread = 0; thread < threads->nr; thread++) {
+		for (thread = 0; thread < nthreads; thread++) {
 			int group_fd;
 
-			if (!evsel->cgrp)
+			if (!evsel->cgrp && !evsel->system_wide)
 				pid = threads->map[thread];
 
 			group_fd = get_group_fd(evsel, cpu, thread);
@@ -1103,7 +1124,7 @@ out_close:
 			close(FD(evsel, cpu, thread));
 			FD(evsel, cpu, thread) = -1;
 		}
-		thread = threads->nr;
+		thread = nthreads;
 	} while (--cpu >= 0);
 	return err;
 }