From: Thara Gopinath <thara.gopinath@linaro.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: mingo@redhat.com, peterz@infradead.org, rui.zhang@intel.com,
linux-kernel@vger.kernel.org, amit.kachhap@gmail.com,
viresh.kumar@linaro.org, javi.merino@kernel.org,
edubezval@gmail.com, daniel.lezcano@linaro.org,
vincent.guittot@linaro.org, nicolas.dechesne@linaro.org,
bjorn.andersson@linaro.org, dietmar.eggemann@arm.com
Subject: Re: [PATCH V2 0/3] Introduce Thermal Pressure
Date: Wed, 17 Apr 2019 13:28:19 -0400 [thread overview]
Message-ID: <5CB76233.9080508@linaro.org> (raw)
In-Reply-To: <20190417055514.GA27400@gmail.com>
On 04/17/2019 01:55 AM, Ingo Molnar wrote:
>
> * Ingo Molnar <mingo@kernel.org> wrote:
>
>> * Thara Gopinath <thara.gopinath@linaro.org> wrote:
>>
>>> The test results below shows 3-5% improvement in performance when
>>> using the third solution compared to the default system today where
>>> scheduler is unware of cpu capacity limitations due to thermal events.
>>
>> The numbers look very promising!
>>
>> I've rearranged the results to make the performance properties of the
>> various approaches and parameters easier to see:
>>
>> (seconds, lower is better)
>>
>> Hackbench Aobench Dhrystone
>> ========= ======= =========
>> Vanilla kernel (No Thermal Pressure) 10.21 141.58 1.14
>> Instantaneous thermal pressure 10.16 141.63 1.15
>> Thermal Pressure Averaging:
>> - PELT fmwk 9.88 134.48 1.19
>> - non-PELT Algo. Decay : 500 ms 9.94 133.62 1.09
>> - non-PELT Algo. Decay : 250 ms 7.52 137.22 1.012
>> - non-PELT Algo. Decay : 125 ms 9.87 137.55 1.12
>
> So what I forgot to say is that IMO your results show robust improvements
> over the vanilla kernel of around 5%, with a relatively straightforward
> thermal pressure metric. So I suspect we could do something like this, if
> there was a bit more measurements done to get the best decay period
> established - the 125-250-500 msecs results seem a bit coarse and not
> entirely unambiguous.
To give you the background, I started with decay period of 500 ms. No
other reason except the previous version of rt-pressure that existed in
the scheduler employed a 500 ms decay period. Then the idea was to
decrease the decay period by half and see what happens and so on. But I
agree, that it is a bit coarse. I will probably get around to
implementing some of your suggestions to capture more granular results
in the next few weeks.
>
> In terms of stddev: the perf stat --pre hook could be used to add a dummy
> benchmark run, to heat up the test system, to get more reliable, less
> noisy numbers?
>
> BTW., that big improvement in hackbench results to 7.52 at 250 msecs, is
> that real, or a fluke perhaps?
For me, it is an anomaly. Having said that, I did rerun the tests with
this configuration at least twice(if not more) and the results were
similar. It is an anomaly because I have no explanation as to why there
is so much improvement at the 250 ms decay period.
>
> Thanks,
>
> Ingo
>
--
Regards
Thara
next prev parent reply other threads:[~2019-04-17 17:28 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-16 19:38 [PATCH V2 0/3] Introduce Thermal Pressure Thara Gopinath
2019-04-16 19:38 ` [PATCH V2 1/3] Calculate " Thara Gopinath
2019-04-18 10:14 ` Quentin Perret
2019-04-24 4:13 ` Thara Gopinath
2019-04-24 16:38 ` Peter Zijlstra
2019-04-24 16:45 ` Peter Zijlstra
2019-04-25 10:57 ` Quentin Perret
2019-04-25 12:45 ` Vincent Guittot
2019-04-25 12:47 ` Quentin Perret
2019-04-26 14:17 ` Thara Gopinath
2019-05-08 12:41 ` Quentin Perret
2019-04-16 19:38 ` [PATCH V2 2/3] sched/fair: update cpu_capcity to reflect thermal pressure Thara Gopinath
2019-04-16 19:38 ` [PATCH V3 3/3] thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping Thara Gopinath
2019-04-18 9:48 ` Quentin Perret
2019-04-23 22:38 ` Thara Gopinath
2019-04-24 15:56 ` Ionela Voinescu
2019-04-26 10:24 ` Thara Gopinath
2019-04-25 10:45 ` Quentin Perret
2019-04-25 12:04 ` Vincent Guittot
2019-04-25 12:50 ` Quentin Perret
2019-04-26 13:47 ` Thara Gopinath
2019-04-24 16:47 ` Peter Zijlstra
2019-04-17 5:36 ` [PATCH V2 0/3] Introduce Thermal Pressure Ingo Molnar
2019-04-17 5:55 ` Ingo Molnar
2019-04-17 17:28 ` Thara Gopinath [this message]
2019-04-17 17:18 ` Thara Gopinath
2019-04-17 18:29 ` Ingo Molnar
2019-04-18 0:07 ` Thara Gopinath
2019-04-18 9:22 ` Quentin Perret
2019-04-24 16:34 ` Peter Zijlstra
2019-04-25 17:33 ` Ingo Molnar
2019-04-25 17:44 ` Ingo Molnar
2019-04-26 7:08 ` Vincent Guittot
2019-04-26 8:35 ` Ingo Molnar
2019-04-24 15:57 ` Ionela Voinescu
2019-04-26 11:50 ` Thara Gopinath
2019-04-26 14:46 ` Ionela Voinescu
2019-04-29 13:29 ` Ionela Voinescu
2019-04-30 14:39 ` Ionela Voinescu
2019-04-30 16:10 ` Thara Gopinath
2019-05-02 10:44 ` Ionela Voinescu
2019-04-30 15:57 ` Thara Gopinath
2019-04-30 16:02 ` Thara Gopinath
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