linux-kernel - [PATCH 02/22] perf stat: Fix shadow stats for clock events

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Message-Id: <20181130182652.23620-3-acme@kernel.org>
Date:   Fri, 30 Nov 2018 15:26:32 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Clark Williams <williams@...hat.com>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jin Yao <yao.jin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Richter <tmricht@...ux.vnet.ibm.com>,
        yuzhoujian@...ichuxing.com,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 02/22] perf stat: Fix shadow stats for clock events

From: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>

Commit 0aa802a79469 ("perf stat: Get rid of extra clock display
function") introduced scale and unit for clock events. Thus,
perf_stat__update_shadow_stats() now saves scaled values of clock events
in msecs, instead of original nsecs. But while calculating values of
shadow stats we still consider clock event values in nsecs. This results
in a wrong shadow stat values. Ex,

  # ./perf stat -e task-clock,cycles ls
    <SNIP>
              2.60 msec task-clock:u    #    0.877 CPUs utilized
         2,430,564      cycles:u        # 1215282.000 GHz

Fix this by saving original nsec values for clock events in
perf_stat__update_shadow_stats(). After patch:

  # ./perf stat -e task-clock,cycles ls
    <SNIP>
              3.14 msec task-clock:u    #    0.839 CPUs utilized
         3,094,528      cycles:u        #    0.985 GHz

Suggested-by: Jiri Olsa <jolsa@...hat.com>
Reported-by: Anton Blanchard <anton@...ba.org>
Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Reviewed-by: Jiri Olsa <jolsa@...nel.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Jin Yao <yao.jin@...ux.intel.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Thomas Richter <tmricht@...ux.vnet.ibm.com>
Cc: yuzhoujian@...ichuxing.com
Fixes: 0aa802a79469 ("perf stat: Get rid of extra clock display function")
Link: http://lkml.kernel.org/r/20181116042843.24067-1-ravi.bangoria@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/stat-shadow.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
index f0a8cec55c47..3c22c58b3e90 100644
--- a/tools/perf/util/stat-shadow.c
+++ b/tools/perf/util/stat-shadow.c
@@ -209,11 +209,12 @@ void perf_stat__update_shadow_stats(struct perf_evsel *counter, u64 count,
 				    int cpu, struct runtime_stat *st)
 {
 	int ctx = evsel_context(counter);
+	u64 count_ns = count;
 
 	count *= counter->scale;
 
 	if (perf_evsel__is_clock(counter))
-		update_runtime_stat(st, STAT_NSECS, 0, cpu, count);
+		update_runtime_stat(st, STAT_NSECS, 0, cpu, count_ns);
 	else if (perf_evsel__match(counter, HARDWARE, HW_CPU_CYCLES))
 		update_runtime_stat(st, STAT_CYCLES, ctx, cpu, count);
 	else if (perf_stat_evsel__is(counter, CYCLES_IN_TX))
-- 
2.19.1