perf evsel: Support event groups

The perf_evsel__open now have an extra boolean argument specifying if
event grouping is desired.

The first file descriptor created on a CPU becomes the group leader.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 17 insertions, 10 deletions

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index f5cfed60af98..da473ec93c75 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -128,7 +128,7 @@ int __perf_evsel__read(struct perf_evsel *evsel,
 }
 
 static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
-                              struct thread_map *threads)
+                              struct thread_map *threads, bool group)
 {
         int cpu, thread;
 
@@ -137,12 +137,18 @@ static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
                 return -1;
 
         for (cpu = 0; cpu < cpus->nr; cpu++) {
+                int group_fd = -1;
+
                 for (thread = 0; thread < threads->nr; thread++) {
                         FD(evsel, cpu, thread) = sys_perf_event_open(&evsel->attr,
                                                                      threads->map[thread],
-                                                                     cpus->map[cpu], -1, 0);
+                                                                     cpus->map[cpu],
+                                                                     group_fd, 0);
                         if (FD(evsel, cpu, thread) < 0)
                                 goto out_close;
+
+                        if (group && group_fd == -1)
+                                group_fd = FD(evsel, cpu, thread);
                 }
         }
 
@@ -175,10 +181,9 @@ static struct {
         .threads = { -1, },
 };
 
-int perf_evsel__open(struct perf_evsel *evsel,
-                     struct cpu_map *cpus, struct thread_map *threads)
+int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
+                     struct thread_map *threads, bool group)
 {
-
         if (cpus == NULL) {
                 /* Work around old compiler warnings about strict aliasing */
                 cpus = &empty_cpu_map.map;
@@ -187,15 +192,17 @@ int perf_evsel__open(struct perf_evsel *evsel,
         if (threads == NULL)
                 threads = &empty_thread_map.map;
 
-        return __perf_evsel__open(evsel, cpus, threads);
+        return __perf_evsel__open(evsel, cpus, threads, group);
 }
 
-int perf_evsel__open_per_cpu(struct perf_evsel *evsel, struct cpu_map *cpus)
+int perf_evsel__open_per_cpu(struct perf_evsel *evsel,
+                             struct cpu_map *cpus, bool group)
 {
-        return __perf_evsel__open(evsel, cpus, &empty_thread_map.map);
+        return __perf_evsel__open(evsel, cpus, &empty_thread_map.map, group);
 }
 
-int perf_evsel__open_per_thread(struct perf_evsel *evsel, struct thread_map *threads)
+int perf_evsel__open_per_thread(struct perf_evsel *evsel,
+                                struct thread_map *threads, bool group)
 {
-        return __perf_evsel__open(evsel, &empty_cpu_map.map, threads);
+        return __perf_evsel__open(evsel, &empty_cpu_map.map, threads, group);
 }