This is a note to let you know that I've just added the patch titled
perf metric: Don't remove scale from counts
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-metric-don-t-remove-scale-from-counts.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cf889eab2e779452375cd2bba2df3aec08c72d21
Author: Ian Rogers <irogers@xxxxxxxxxx>
Date: Fri Feb 9 12:49:47 2024 -0800
perf metric: Don't remove scale from counts
[ Upstream commit 6d6be5eb45b423a37d746d3ee0fd0c78f76ead9f ]
Counts were switched from the scaled saved value form to the
aggregated count to avoid double accounting. When this happened the
removing of scaling for a count should have been removed, however, it
wasn't and this wasn't observed as it normally doesn't matter because
a counter's scale is 1. A problem was observed with RAPL events that
are scaled.
Fixes: 37cc8ad77cf8 ("perf metric: Directly use counts rather than saved_value")
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
Reviewed-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Cc: K Prateek Nayak <kprateek.nayak@xxxxxxx>
Cc: James Clark <james.clark@xxxxxxx>
Cc: Kaige Ye <ye@xxxxxxxxx>
Cc: John Garry <john.g.garry@xxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240209204947.3873294-5-irogers@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
index e31426167852a..cf573ff3fa84f 100644
--- a/tools/perf/util/stat-shadow.c
+++ b/tools/perf/util/stat-shadow.c
@@ -414,12 +414,7 @@ static int prepare_metric(struct evsel **metric_events,
val = NAN;
source_count = 0;
} else {
- /*
- * If an event was scaled during stat gathering,
- * reverse the scale before computing the
- * metric.
- */
- val = aggr->counts.val * (1.0 / metric_events[i]->scale);
+ val = aggr->counts.val;
source_count = evsel__source_count(metric_events[i]);
}
}
