From: Lukasz Luba <lukasz.luba@arm.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Vincent Donnefort <vincent.donnefort@arm.com>,
peterz@infradead.org, rjw@rjwysocki.net,
vincent.guittot@linaro.org, qperret@google.com,
linux-kernel@vger.kernel.org, ionela.voinescu@arm.com,
dietmar.eggemann@arm.com
Subject: Re: [PATCH v2 0/3] EM / PM: Inefficient OPPs
Date: Wed, 26 May 2021 09:56:39 +0100 [thread overview]
Message-ID: <068fa9c4-2b55-3d75-adc7-cf5ef2174b12@arm.com> (raw)
In-Reply-To: <20210526034751.5fl4kekq73gqy2wq@vireshk-i7>
Hi Viresh,
On 5/26/21 4:47 AM, Viresh Kumar wrote:
[snip]
>
> First of all, sorry about not replying earlier. I have seen this earlier and was
> shying away to receive some feedback from Rafael/Peter instead :(
>
> I think the problem you mention is genuine, I have realized it in the past,
> discussed with Vincent Guittot (cc'd) but never was able to get to a proper
> solution as the EM model wasn't there then.
>
> I have seen your approach (from top level) and I feel maybe we can improve upon
> the whole idea a bit, lemme know what you think. The problem I see with this
> approach is the unnecessary updates to schedutil that this series makes, which
> IMHO is the wrong thing to do. Schedutil isn't the only governor and such
> changes will end up making the performance delta between ondemand and schedutil
> even more (difference based on their core design philosophy is fine, but these
> are improvements which each of them should enjoy). And if another governor wants
> these smart decisions to be added there, then it is trouble again.
>
> Since the whole thing depends on EM and OPPs, I think we can actually do this.
>
> When the cpufreq driver registers with the EM core, lets find all the
> Inefficient OPPs and disable them once and for all. Of course, this must be done
> on voluntarily basis, a flag from the drivers will do. With this, we won't be
> required to update any thing at any of the governors end.
>
> Will that work ?
>
No, these OPPs have to stay because they are used in thermal for cooling
states. DT cooling devices might have them set as a scope of possible
states. We don't want to break existing platforms, don't we?
We want to 'avoid' those OPPs when possible (no thermal pressure), but
we might have to use them sometimes.
Regards,
Lukasz
next prev parent reply other threads:[~2021-05-26 8:56 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-21 16:54 [PATCH v2 0/3] EM / PM: Inefficient OPPs Vincent Donnefort
2021-05-21 16:54 ` [PATCH v2 1/3] PM / EM: Fix inefficient state detection Vincent Donnefort
2021-05-24 12:41 ` Lukasz Luba
2021-05-25 9:50 ` Quentin Perret
2021-05-21 16:54 ` [PATCH v2 2/3] PM / EM: Extend em_perf_domain with a flag field Vincent Donnefort
2021-05-24 12:44 ` Lukasz Luba
2021-05-25 9:54 ` Quentin Perret
2021-05-21 16:54 ` [PATCH v2 3/3] PM / EM: Skip inefficient OPPs Vincent Donnefort
2021-05-24 12:55 ` Lukasz Luba
2021-05-25 8:48 ` Peter Zijlstra
2021-05-25 9:21 ` Vincent Donnefort
2021-05-25 10:00 ` Vincent Donnefort
2021-05-28 5:09 ` Viresh Kumar
2021-06-01 8:47 ` Vincent Donnefort
2021-06-01 8:56 ` Viresh Kumar
2021-06-01 9:07 ` Quentin Perret
2021-06-01 9:13 ` Viresh Kumar
2021-05-25 9:33 ` Quentin Perret
2021-05-25 9:46 ` Vincent Donnefort
2021-05-25 11:03 ` Lukasz Luba
2021-05-25 13:06 ` Quentin Perret
2021-05-25 13:34 ` Lukasz Luba
2021-05-25 9:47 ` Vincent Donnefort
2021-05-28 5:04 ` Viresh Kumar
2021-05-28 9:00 ` Lukasz Luba
2021-05-26 3:47 ` [PATCH v2 0/3] EM / PM: Inefficient OPPs Viresh Kumar
2021-05-26 8:56 ` Lukasz Luba [this message]
2021-05-26 9:33 ` Viresh Kumar
2021-05-27 7:13 ` Lukasz Luba
2021-05-26 9:01 ` Vincent Donnefort
2021-05-26 9:38 ` Viresh Kumar
2021-05-26 9:39 ` Viresh Kumar
2021-05-26 10:24 ` Lukasz Luba
2021-05-26 10:39 ` Lukasz Luba
2021-05-26 11:50 ` Lukasz Luba
2021-05-26 13:49 ` Vincent Donnefort
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=068fa9c4-2b55-3d75-adc7-cf5ef2174b12@arm.com \
--to=lukasz.luba@arm.com \
--cc=dietmar.eggemann@arm.com \
--cc=ionela.voinescu@arm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=qperret@google.com \
--cc=rjw@rjwysocki.net \
--cc=vincent.donnefort@arm.com \
--cc=vincent.guittot@linaro.org \
--cc=viresh.kumar@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).