From: Thomas Gleixner <tglx@linutronix.de>
To: Pingfan Liu <piliu@redhat.com>
Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
Waiman Long <longman@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Pierre Gondois <pierre.gondois@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Baoquan He <bhe@redhat.com>, Ingo Molnar <mingo@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Valentin Schneider <vschneid@redhat.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Joel Granados <joel.granados@kernel.org>
Subject: Re: [RFC 2/3] kernel/cpu: Mark nonboot cpus as inactive when shutting down nonboot cpus
Date: Tue, 28 Oct 2025 13:59:11 +0100 [thread overview]
Message-ID: <87qzunuqqo.ffs@tglx> (raw)
In-Reply-To: <aQAvnjVvJOUx78Nk@fedora>
On Tue, Oct 28 2025 at 10:51, Pingfan Liu wrote:
> On Mon, Oct 27, 2025 at 06:06:32PM +0100, Thomas Gleixner wrote:
>> When kexec() is in progress, then running user space tasks at all is a
>> completely pointless exercise.
>>
>> So the obvious solution to the problem is to freeze all user space tasks
>
> I agree, but what about a less intrusive approach? Simply stopping the
> DL tasks should suffice, as everything works correctly without them.
What's intrusive about that? Task freezing exists already.
> I have a draft patch ready. Let's discuss it and go from there.
>
>> when kexec() is invoked. No horrible hacks in the deadline scheduler and
>> elsewhere required to make that work. No?
>
> To clarify, skipping the dl_bw_deactivate() validation is necessary
> because it prevents CPU hot-removal.
If you freeze stuff there is nothing to do. Hibernation works exactly
that way without any magic hacks in a particular scheduling class, no?
Thanks,
tglx
next prev parent reply other threads:[~2025-10-28 12:59 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-22 12:13 [RFC 0/3] kexec: Force kexec to proceed under heavy deadline load Pingfan Liu
2025-10-22 12:13 ` [RFC 1/3] sched/deadline: Skip the deadline bandwidth check if kexec_in_progress Pingfan Liu
2025-10-22 12:13 ` [RFC 2/3] kernel/cpu: Mark nonboot cpus as inactive when shutting down nonboot cpus Pingfan Liu
2025-10-27 17:06 ` Thomas Gleixner
2025-10-28 2:51 ` Pingfan Liu
2025-10-28 12:59 ` Thomas Gleixner [this message]
2025-10-29 11:36 ` Pingfan Liu
2025-10-29 12:13 ` Thomas Gleixner
2025-10-29 13:39 ` Pingfan Liu
2025-10-22 12:13 ` [RFC 3/3] kexec_core: Promote the kexec to DL task Pingfan Liu
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