From: Ionela Voinescu <ionela.voinescu@arm.com>
To: Thara Gopinath <thara.gopinath@linaro.org>
Cc: mingo@redhat.com, peterz@infradead.org,
vincent.guittot@linaro.org, rui.zhang@intel.com,
edubezval@gmail.com, qperret@google.com,
linux-kernel@vger.kernel.org, amit.kachhap@gmail.com,
javi.merino@kernel.org, daniel.lezcano@linaro.org
Subject: Re: [Patch v4 6/6] sched: thermal: Enable tuning of decay period
Date: Tue, 5 Nov 2019 21:29:01 +0000 [thread overview]
Message-ID: <20191105212735.GA32353@e108754-lin> (raw)
In-Reply-To: <5DC1DADE.60603@linaro.org>
On Tuesday 05 Nov 2019 at 15:26:06 (-0500), Thara Gopinath wrote:
> On 11/04/2019 11:12 AM, Ionela Voinescu wrote:
> > Hi Thara,
> >
> > On Tuesday 22 Oct 2019 at 16:34:25 (-0400), Thara Gopinath wrote:
> >> Thermal pressure follows pelt signas which means the
> >> decay period for thermal pressure is the default pelt
> >> decay period. Depending on soc charecteristics and thermal
> >> activity, it might be beneficial to decay thermal pressure
> >> slower, but still in-tune with the pelt signals.
> >
> > I wonder if it can be beneficial to decay thermal pressure faster as
> > well.
> >
> > This implementation makes 32 (LOAD_AVG_PERIOD) the minimum half-life
> > of the thermal pressure samples. This results in more than 100ms for a
> > sample to decay significantly and therefore let's say it can take more
> > than 100ms for capacity to return to (close to) max when the CPU is no
> > longer capped. This value seems high to me considering that a minimum
> > value should result in close to 'instantaneous' behaviour, when there
> > are thermal capping mechanisms that can react in ~20ms (hikey960 has a
> > polling delay of 25ms, if I'm remembering correctly).
> >
> > I agree 32ms seems like a good default but given that you've made this
> > configurable as to give users options, I'm wondering if it would be
> > better to cover a wider range.
> >
[...]
>
> Hi Ionela,
>
[...]
>
> Regarding a slower decay, we need a strong case for it.
>
>
I think you mean faster decay, if you refer to my comment above.
To be blunt, I'm not sure there is a strong case for either kind of
dacay, if we look at the test results only. There is a theoretical case
for both, in my opinion and given that the purpose of this patch is to
give options to platform with different thermal characteristics, I do
believe it's worth providing a good range of options for the decay
period.
Thanks,
Ionela.
>
> --
> Warm Regards
> Thara
next prev parent reply other threads:[~2019-11-05 21:29 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-22 20:34 [Patch v4 0/6] Introduce Thermal Pressure Thara Gopinath
2019-10-22 20:34 ` [Patch v4 1/6] sched/pelt.c: Add support to track thermal pressure Thara Gopinath
2019-10-31 9:47 ` Ionela Voinescu
2019-10-22 20:34 ` [Patch v4 2/6] sched: Add infrastructure to store and update instantaneous " Thara Gopinath
2019-10-28 15:21 ` Peter Zijlstra
2019-10-30 21:37 ` Thara Gopinath
2019-11-01 12:17 ` Dietmar Eggemann
2019-11-01 20:57 ` Thara Gopinath
2019-11-04 17:29 ` Dietmar Eggemann
2019-11-04 17:34 ` Vincent Guittot
2019-11-04 17:41 ` Dietmar Eggemann
2019-11-04 17:48 ` Vincent Guittot
2019-10-22 20:34 ` [Patch v4 3/6] sched/fair: Enable CFS periodic tick to update " Thara Gopinath
2019-10-28 15:24 ` Peter Zijlstra
2019-10-28 15:27 ` Peter Zijlstra
2019-10-30 21:41 ` Thara Gopinath
2019-10-31 16:11 ` Dietmar Eggemann
2019-10-31 16:46 ` Thara Gopinath
2019-10-22 20:34 ` [Patch v4 4/6] sched/fair: update cpu_capcity to reflect " Thara Gopinath
2019-10-23 12:28 ` Qais Yousef
2019-10-28 15:30 ` Peter Zijlstra
2019-10-31 10:53 ` Qais Yousef
2019-10-31 15:38 ` Dietmar Eggemann
2019-10-31 15:48 ` Vincent Guittot
2019-10-31 16:17 ` Dietmar Eggemann
2019-10-31 16:31 ` Vincent Guittot
2019-10-31 16:44 ` Dietmar Eggemann
2019-10-31 16:03 ` Thara Gopinath
2019-10-31 16:56 ` Qais Yousef
2019-10-22 20:34 ` [Patch v4 5/6] thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping Thara Gopinath
2019-10-28 15:33 ` Peter Zijlstra
2019-10-31 16:29 ` Dietmar Eggemann
2019-10-31 16:38 ` Vincent Guittot
2019-11-01 15:47 ` Ionela Voinescu
2019-11-01 21:04 ` Thara Gopinath
2019-11-04 14:41 ` Ionela Voinescu
2019-10-31 16:46 ` Thara Gopinath
2019-10-22 20:34 ` [Patch v4 6/6] sched: thermal: Enable tuning of decay period Thara Gopinath
2019-10-28 15:42 ` Peter Zijlstra
2019-11-04 16:12 ` Ionela Voinescu
2019-11-05 20:26 ` Thara Gopinath
2019-11-05 21:29 ` Ionela Voinescu [this message]
2019-10-29 15:34 ` [Patch v4 0/6] Introduce Thermal Pressure Daniel Lezcano
2019-10-31 10:07 ` Ionela Voinescu
2019-10-31 11:54 ` Daniel Lezcano
2019-10-31 12:57 ` Ionela Voinescu
2019-10-31 17:48 ` Daniel Lezcano
2019-10-31 9:44 ` Ionela Voinescu
2019-10-31 16:41 ` Thara Gopinath
2019-10-31 16:52 ` Thara Gopinath
2019-11-05 21:04 ` Ionela Voinescu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191105212735.GA32353@e108754-lin \
--to=ionela.voinescu@arm.com \
--cc=amit.kachhap@gmail.com \
--cc=daniel.lezcano@linaro.org \
--cc=edubezval@gmail.com \
--cc=javi.merino@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=qperret@google.com \
--cc=rui.zhang@intel.com \
--cc=thara.gopinath@linaro.org \
--cc=vincent.guittot@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).