linux-kernel - [PATCH v2 1/2] libperf: Add processing to scale the counters obtained during the read() system call when multiplexing

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Date:   Wed, 22 Sep 2021 19:16:26 +0900
From:   Shunsuke Nakamura <nakamura.shun@...itsu.com>
To:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        jolsa@...hat.com, namhyung@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: [PATCH v2 1/2] libperf: Add processing to scale the counters obtained during the read() system call when multiplexing

From: nakamura shunsuke <nakamura.shun@...itsu.com>

perf_evsel__read() scales counters obtained by RDPMC during multiplexing, but
does not scale counters obtained by read() system call.

Add processing to perf_evsel__read() to scale the counters obtained during the
read() system call when multiplexing.


Signed-off-by: Shunsuke Nakamura <nakamura.shun@...itsu.com>
---
 tools/lib/perf/evsel.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index 8441e3e1aaac..0ebd1d34436f 100644
--- a/tools/lib/perf/evsel.c
+++ b/tools/lib/perf/evsel.c
@@ -18,6 +18,7 @@
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <asm/bug.h>
+#include <linux/math64.h>
 
 void perf_evsel__init(struct perf_evsel *evsel, struct perf_event_attr *attr,
 		      int idx)
@@ -321,6 +322,11 @@ int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,
 	if (readn(*fd, count->values, size) <= 0)
 		return -errno;
 
+	if (count->ena != count->run) {
+		if (count->run != 0)
+			count->val = mul_u64_u64_div64(count->val, count->ena, count->run);
+	}
+
 	return 0;
 }
 
-- 
2.27.0