linux-kernel - [PATCH 4.19 75/87] perf stat: Fix shadow stats for clock events

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Date:   Tue,  3 Mar 2020 18:44:06 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jiri Olsa <jolsa@...hat.com>,
        Anton Blanchard <anton@...ba.org>,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
        Jiri Olsa <jolsa@...nel.org>,
        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>,
        Tommi Rantala <tommi.t.rantala@...ia.com>
Subject: [PATCH 4.19 75/87] perf stat: Fix shadow stats for clock events

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

commit 57ddf09173c1e7d0511ead8924675c7198e56545 upstream.

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>
Cc: Tommi Rantala <tommi.t.rantala@...ia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 tools/perf/util/stat-shadow.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/tools/perf/util/stat-shadow.c
+++ b/tools/perf/util/stat-shadow.c
@@ -209,11 +209,12 @@ void perf_stat__update_shadow_stats(stru
 				    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))