linux-kernel - Re: [PATCH] perf stat: Fix shadow stats for clock events

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Date:   Tue, 27 Nov 2018 13:50:44 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, alexander.shishkin@...ux.intel.com,
        namhyung@...nel.org, yao.jin@...ux.intel.com,
        linux-kernel@...r.kernel.org, yuzhoujian@...ichuxing.com,
        tmricht@...ux.vnet.ibm.com, anton@...ba.org,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: Re: [PATCH] perf stat: Fix shadow stats for clock events



On 11/16/18 7:05 PM, Jiri Olsa wrote:
> On Fri, Nov 16, 2018 at 09:58:43AM +0530, Ravi Bangoria wrote:
>> 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
>>
>> Reported-by: Anton Blanchard <anton@...ba.org>
>> Suggested-by: Jiri Olsa <jolsa@...hat.com>
>> Fixes: 0aa802a79469 ("perf stat: Get rid of extra clock display function")
>> Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
> 
> Reviewed-by: Jiri Olsa <jolsa@...nel.org>

Hi Arnaldo, Please pull this.

Thanks.