From: Hillf Danton <hdanton@sina.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: Pavan Kondeti <quic_pkondeti@quicinc.com>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
quic_charante@quicinc.com
Subject: Re: PSI idle-shutoff
Date: Wed, 12 Oct 2022 14:20:34 +0800 [thread overview]
Message-ID: <20221012062034.486-1-hdanton@sina.com> (raw)
In-Reply-To: <CAJuCfpG=bADguJWdxV4ZhTze9fmKP2bhsbf0xzbd06Fhr4_U5w@mail.gmail.com>
On 11 Oct 2022 10:11:58 -0700 Suren Baghdasaryan <surenb@google.com>
>On Tue, Oct 11, 2022 at 4:38 AM Hillf Danton <hdanton@sina.com> wrote:
>>
>> Given activities on remote CPUs, can you specify what prevents psi_avgs_work
>> from being scheduled on remote CPUs if for example the local CPU has been
>> idle for a second?
>
> I'm not a scheduler expert but I can imagine some work that finished
> running on a big core A and generated some activity since the last
> time psi_avgs_work executed. With no other activity the next
> psi_avgs_work could be scheduled on a small core B to conserve power.
Given core A and B, nothing prevents.
> There might be other cases involving cpuset limitation changes or cpu
> offlining but I didn't think too hard about these. The bottom line, I
> don't think we should be designing mechanisms which rely on
> assumptions about how tasks will be scheduled. Even if these
The tasks here makes me guess that we are on different pages - scheduling
work has little to do with how tasks are scheduled, and is no more than
queuing work on the system_wq in the case of psi_avgs_work,
> assumptions are correct today they might change in the future and
> things will break in unexpected places.
with nothing assumed.
next prev parent reply other threads:[~2022-10-12 6:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20220913140817.GA9091@hu-pkondeti-hyd.qualcomm.com>
2022-10-10 10:57 ` PSI idle-shutoff Hillf Danton
2022-10-10 21:16 ` Suren Baghdasaryan
2022-10-11 11:38 ` Hillf Danton
2022-10-11 17:11 ` Suren Baghdasaryan
2022-10-12 6:20 ` Hillf Danton [this message]
2022-10-12 15:40 ` Suren Baghdasaryan
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=20221012062034.486-1-hdanton@sina.com \
--to=hdanton@sina.com \
--cc=hannes@cmpxchg.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=quic_charante@quicinc.com \
--cc=quic_pkondeti@quicinc.com \
--cc=surenb@google.com \
/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