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| author | Anton Blanchard <anton@samba.org> | 2010-05-04 21:19:15 +1000 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2010-05-04 10:54:09 -0300 |
| commit | 02bf60aad7d5912dfcdbe0154f1bd67ea7a8301e (patch) | |
| tree | 4d0c009e30079b127e0d7b01cdd30d8375e44c7c /tools | |
| parent | 11d232ec285b07860670277c8ab3f6076f7bce1e (diff) | |
| download | linux-02bf60aad7d5912dfcdbe0154f1bd67ea7a8301e.tar.gz linux-02bf60aad7d5912dfcdbe0154f1bd67ea7a8301e.tar.bz2 linux-02bf60aad7d5912dfcdbe0154f1bd67ea7a8301e.zip | |
perf: Fix performance issue with perf report
On a large machine we spend a lot of time in perf_header__find_attr when
running perf report.
If we are parsing a file without PERF_SAMPLE_ID then for each sample we call
perf_header__find_attr and loop through all counter IDs, never finding a match.
As the machine gets larger there are more per cpu counters and we spend an
awful lot of time in there.
The patch below initialises each sample id to -1ULL and checks for this in
perf_header__find_attr. We may need to do something more intelligent eventually
(eg a hash lookup from counter id to attr) but this at least fixes the most
common usage of perf report.
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eric B Munson <ebmunson@us.ibm.com>
Acked-by: Eric B Munson <ebmunson@us.ibm.com>
LKML-Reference: <20100504111915.GB14636@kryten>
Signed-off-by: Anton Blanchard <anton@samba.org>
--
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/perf/util/event.c | 1 | ||||
| -rw-r--r-- | tools/perf/util/header.c | 8 |
2 files changed, 9 insertions, 0 deletions
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c index 1757b0ffeaa9..2477270c1d3f 100644 --- a/tools/perf/util/event.c +++ b/tools/perf/util/event.c @@ -713,6 +713,7 @@ int event__parse_sample(event_t *event, u64 type, struct sample_data *data) array++; } + data->id = -1ULL; if (type & PERF_SAMPLE_ID) { data->id = *array; array++; diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index 2b9f898efea6..8847bec64c54 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -922,6 +922,14 @@ perf_header__find_attr(u64 id, struct perf_header *header) { int i; + /* + * We set id to -1 if the data file doesn't contain sample + * ids. Check for this and avoid walking through the entire + * list of ids which may be large. + */ + if (id == -1ULL) + return NULL; + for (i = 0; i < header->attrs; i++) { struct perf_header_attr *attr = header->attr[i]; int j; |