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Subject[tip:perf/core] perf evlist: Do not poll events that use the system_wide flag
Commit-ID:  f90d194a867a5a1db51789b8c4e99bcd196be6bb
Gitweb: http://git.kernel.org/tip/f90d194a867a5a1db51789b8c4e99bcd196be6bb
Author: Adrian Hunter <adrian.hunter@intel.com>
AuthorDate: Tue, 11 Nov 2014 16:16:39 +0200
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 19 Nov 2014 12:33:48 -0300

perf evlist: Do not poll events that use the system_wide flag

The system_wide flag causes a selected event to be opened always without
a pid.

Consequently it will never get a POLLHUP, but it is used for tracking in
combination with other events, so it should not need to be polled
anyway.

Therefore don't add it for polling.

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/1415715423-15563-2-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/evlist.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 7e23dae..cfbe2b9 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -816,7 +816,15 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
perf_evlist__mmap_get(evlist, idx);
}

- if (__perf_evlist__add_pollfd(evlist, fd, idx) < 0) {
+ /*
+ * The system_wide flag causes a selected event to be opened
+ * always without a pid. Consequently it will never get a
+ * POLLHUP, but it is used for tracking in combination with
+ * other events, so it should not need to be polled anyway.
+ * Therefore don't add it for polling.
+ */
+ if (!evsel->system_wide &&
+ __perf_evlist__add_pollfd(evlist, fd, idx) < 0) {
perf_evlist__mmap_put(evlist, idx);
return -1;
}

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