From: Peter Zijlstra <peterz@infradead.org>
To: Costa Shulyupin <costa.shul@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Waiman Long <longman@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Valentin Schneider <vschneid@redhat.com>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: Interference of CPU hotplug on CPU isolation and Real-Time tasks
Date: Mon, 9 Dec 2024 10:57:30 +0100 [thread overview]
Message-ID: <20241209095730.GG21636@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <CADDUTFzK0FNS_mJ=S2_FH2vS2c5a+gW_qsjf3Hb9k=zzjB4JmA@mail.gmail.com>
On Mon, Dec 09, 2024 at 09:10:35AM +0200, Costa Shulyupin wrote:
> Questions:
> 1. Why stop_machine() is used during the CPU hotplug?
It is the easiest (and most brutal) serialization scheme to ensure
nothing else will poke at the data you're about to change.
> 2. Is it worth testing using stop_one_cpu(), or would that be the
> wrong approach?
Yes, and yes. That is, I'm fairly sure that just trying it will horribly
break stuff, but it is where you want to end up.
> 3. Do you have any additional recommendations?
Audit the full cpu hotplug stack and determine who all relies on this
'implicit' serialization, then proceed to provide alternative solutions
for these sites. Then, at the very end move to stop_one_cpu().
prev parent reply other threads:[~2024-12-09 9:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-09 7:10 Costa Shulyupin
2024-12-09 9:57 ` Peter Zijlstra [this message]
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=20241209095730.GG21636@noisy.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=costa.shul@redhat.com \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=longman@redhat.com \
--cc=tglx@linutronix.de \
--cc=vschneid@redhat.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
all inboxes | Powered by JetHome®