[PATCH 03/11] perf tool: Use PERF_EVENT_IOC_ID perf ioctl to read event id

From: Jiri Olsa
Date: Sat Oct 20 2012 - 10:33:37 EST


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.

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
---
tools/perf/util/evlist.c | 34 ++++++++++++++++++++++++----------
1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 561bdfb..ef13aab 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -290,19 +290,33 @@ static int perf_evlist__id_add_fd(struct perf_evlist *evlist,
struct perf_evsel *evsel,
int cpu, int thread, int fd)
{
- u64 read_data[4] = { 0, };
- int id_idx = 1; /* The first entry is the counter value */
+ u64 id;
+ int ret;

- if (!(evsel->attr.read_format & PERF_FORMAT_ID) ||
- read(fd, &read_data, sizeof(read_data)) == -1)
- return -1;
+ ret = ioctl(fd, PERF_EVENT_IOC_ID, &id);
+ if (!ret)
+ goto add;
+
+ /* Legacy way to get event id.. All hail to old kernels! */
+ if (errno == ENOTTY) {
+ u64 read_data[4] = { 0, };
+ int id_idx = 1; /* The first entry is the counter value */
+
+ if (!(evsel->attr.read_format & PERF_FORMAT_ID) ||
+ read(fd, &read_data, sizeof(read_data)) == -1)
+ return -1;

- if (evsel->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
- ++id_idx;
- if (evsel->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
- ++id_idx;
+ if (evsel->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+ ++id_idx;
+ if (evsel->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+ ++id_idx;
+
+ id = read_data[id_idx];
+ } else if (errno)
+ return -1;

- perf_evlist__id_add(evlist, evsel, cpu, thread, read_data[id_idx]);
+ add:
+ perf_evlist__id_add(evlist, evsel, cpu, thread, id);
return 0;
}

--
1.7.11.4

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