From: Oleg Nesterov <oleg@redhat.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: "Luis Claudio R. Goncalves" <lgoncalv@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Clark Williams <clrkwllms@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>, Tejun Heo <tj@kernel.org>,
David Vernet <dvernet@meta.com>, Barret Rhoden <brho@google.com>,
Josh Don <joshdon@google.com>, Crystal Wood <crwood@redhat.com>,
linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev,
Juri Lelli <juri.lelli@redhat.com>,
Ben Segall <bsegall@google.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ingo Molnar <mingo@redhat.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Wander Lairson Costa <wander@redhat.com>
Subject: Re: [RESEND PATCH] sched: restore the behavior of put_task_struct() for non-rt
Date: Mon, 11 Aug 2025 13:21:20 +0200 [thread overview]
Message-ID: <20250811112119.GC5250@redhat.com> (raw)
In-Reply-To: <20250811110501.nTDNkPnM@linutronix.de>
On 08/11, Sebastian Andrzej Siewior wrote:
>
> On 2025-08-11 12:40:34 [+0200], Oleg Nesterov wrote:
> >
> > What exactly do you think we could do regardless of PREEMPT_RT?
>
> Do what we do now and have one free path for task_struct regardless if
> PREEMPT_RT is enabled or not. The one via RCU which delays the freeing
> until after the grace period.
Ah, got it. I won't really argue, but...
call_rcu() is not free, it obviously delays free_task/etc. To me this
!PREEMPT_RT optimization makes sense.
But lets forget it for the moment. This patch
https://lore.kernel.org/all/aGvTz5VaPFyj0pBV@uudg.org
[PATCH v6] sched: do not call __put_task_struct() on rt if pi_blocked_on is set
removed that optimization by mistake, this doesn't even match the changelog.
I think it should be restored, and this is what the new patch from Luis does.
Then we can discuss this all again and possibly remove it, but this
should be explicitly documented in the changelog.
Oleg.
next prev parent reply other threads:[~2025-08-11 11:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-06 19:43 [RESEND PATCH] sched: restore the behavior of put_task_struct() for non-rt Luis Claudio R. Goncalves
2025-08-11 10:06 ` Sebastian Andrzej Siewior
2025-08-11 10:40 ` Oleg Nesterov
2025-08-11 11:05 ` Sebastian Andrzej Siewior
2025-08-11 11:21 ` Oleg Nesterov [this message]
2025-08-11 12:15 ` Sebastian Andrzej Siewior
-- strict thread matches above, loose matches on Subject: below --
2025-08-25 13:50 Luis Claudio R. Goncalves
2025-09-15 11:15 Luis Claudio R. Goncalves
2025-09-15 11:38 ` Peter Zijlstra
2025-09-15 12:24 ` Sebastian Andrzej Siewior
2025-09-15 14:49 ` Luis Claudio R. Goncalves
2025-09-15 15:31 ` Sebastian Andrzej Siewior
2025-09-15 12:35 ` Oleg Nesterov
2025-09-16 10:09 ` Peter Zijlstra
2025-09-16 11:30 ` Oleg Nesterov
2025-10-17 14:39 ` Oleg Nesterov
2025-10-18 13:11 ` Luis Claudio R. Goncalves
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=20250811112119.GC5250@redhat.com \
--to=oleg@redhat.com \
--cc=bigeasy@linutronix.de \
--cc=brho@google.com \
--cc=bsegall@google.com \
--cc=clrkwllms@kernel.org \
--cc=crwood@redhat.com \
--cc=dietmar.eggemann@arm.com \
--cc=dvernet@meta.com \
--cc=joshdon@google.com \
--cc=juri.lelli@redhat.com \
--cc=lgoncalv@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rt-devel@lists.linux.dev \
--cc=mgorman@suse.de \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
--cc=tj@kernel.org \
--cc=vincent.guittot@linaro.org \
--cc=vschneid@redhat.com \
--cc=wander@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