linux-kernel - Re: [PATCH 0/4 v4] sched/rt: track rt rq utilization

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Message-ID: <CAKfTPtBJwDCFB=tkSYyFK58kOF9C+JjZY=1c=hf3JLG2eB=G5g@mail.gmail.com>
Date:   Sun, 15 Apr 2018 14:00:45 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Dietmar Eggemann <dietmar.eggemann@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>, rjw@...ysocki.net,
        Juri Lelli <juri.lelli@...hat.com>,
        Morten Rasmussen <Morten.Rasmussen@....com>,
        viresh kumar <viresh.kumar@...aro.org>,
        Valentin Schneider <valentin.schneider@....com>
Subject: Re: [PATCH 0/4 v4] sched/rt: track rt rq utilization

Hi Dietmar,

On 15 April 2018 at 13:56, Dietmar Eggemann <dietmar.eggemann@....com> wrote:
> On 03/16/2018 12:25 PM, Vincent Guittot wrote:
>
> [...]
>
>
>> For a 15 seconds long test on a hikey 6220 (octo core cortex A53
>> platfrom),
>> the cpufreq statistics outputs (stats are reset just before the test) :
>> $ cat /sys/devices/system/cpu/cpufreq/policy0/stats/total_trans
>> without patchset : 1230
>> with patchset : 14
>>
>> If we replace the cfs thread of rt-app by a sysbench cpu test, we can see
>> performance improvements:
>>
>> - Without patchset :
>> Test execution summary:
>>      total time:                          15.0009s
>>      total number of events:              4903
>>      total time taken by event execution: 14.9972
>>      per-request statistics:
>>           min:                                  1.23ms
>>           avg:                                  3.06ms
>>           max:                                 13.16ms
>>           approx.  95 percentile:              12.73ms
>>
>> Threads fairness:
>>      events (avg/stddev):           4903.0000/0.00
>>      execution time (avg/stddev):   14.9972/0.00
>>
>> - With patchset:
>> Test execution summary:
>>      total time:                          15.0014s
>>      total number of events:              7694
>>      total time taken by event execution: 14.9979
>>      per-request statistics:
>>           min:                                  1.23ms
>>           avg:                                  1.95ms
>>           max:                                 10.49ms
>>           approx.  95 percentile:              10.39ms
>>
>> Threads fairness:
>>      events (avg/stddev):           7694.0000/0.00
>>      execution time (avg/stddev):   14.9979/0.00
>>
>> The performance improvement is 56% for this use case.
>
>
> How do you get this number? Normally we use the 'total time' value.

The test stop after an defined amount of time with --max-time=15 in my case

>
> [...]