[PATCH v2 2/5] perf record: Prevent override of attr->sample_period for libpfm4 events

Ian Rogers
2020-07-28T08:58:06Z

From: Stephane Eranian <eranian@google.com>

Before:
$ perf record -c 10000 --pfm-events=cycles:period=77777

Would yield a cycles event with period=10000, instead of 77777.

This was due to an ordering issue between libpfm4 parsing
the event string and perf record initializing the event.

This patch fixes the problem by preventing override for
events with attr->sample_period != 0 by the time
perf_evsel__config() is invoked. This seems to have been the
intent of the author.

Signed-off-by: Stephane Eranian <eranian@google.com>
Reviewed-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/evsel.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 811f538f7d77..8afc24e2ec52 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -976,8 +976,7 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts,
* We default some events to have a default interval. But keep
* it a weak assumption overridable by the user.
*/
- if (!attr->sample_period || (opts->user_freq != UINT_MAX ||
- opts->user_interval != ULLONG_MAX)) {
+ if (!attr->sample_period) {
if (opts->freq) {
attr->freq = 1;
attr->sample_freq = opts->freq;
--
2.28.0.163.g6104cc2f0b6-goog