Commit e2b5abe0 authored Apr 04, 2012 by Jiri Olsa Committed by Arnaldo Carvalho de Melo Aug 07, 2013

perf evlist: Use PERF_EVENT_IOC_ID perf ioctl to read event id



Changing the way we retrieve the event ID. Instead of parsing out
the ID out of the read data, using the PERF_EVENT_IOC_ID ioctl.

Keeping the old way in place to support kernels without
PERF_EVENT_IOC_ID ioctl support.

This will be useful for retrieving the event ID for events
with PERF_FORMAT_GROUP read format set, where it's impossible
to get correct event id out of the read call data.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-psgb4n7kte8e6tfenbe7nj2h@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 6f5ab001

tools/perf/util/evlist.c

+15 −1

Original line number	Diff line number	Diff line
		@@ -302,6 +302,17 @@ static int perf_evlist__id_add_fd(struct perf_evlist *evlist,
		{
		u64 read_data[4] = { 0, };
		int id_idx = 1; /* The first entry is the counter value */
		u64 id;
		int ret;

		ret = ioctl(fd, PERF_EVENT_IOC_ID, &id);
		if (!ret)
		goto add;

		if (errno != ENOTTY)
		return -1;

		/* Legacy way to get event id.. All hail to old kernels! */

		if (!(evsel->attr.read_format & PERF_FORMAT_ID) \|\|
		read(fd, &read_data, sizeof(read_data)) == -1)
		@@ -312,7 +323,10 @@ static int perf_evlist__id_add_fd(struct perf_evlist *evlist,
		if (evsel->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
		++id_idx;

		perf_evlist__id_add(evlist, evsel, cpu, thread, read_data[id_idx]);
		id = read_data[id_idx];

		add:
		perf_evlist__id_add(evlist, evsel, cpu, thread, id);
		return 0;
		}