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From: Tejun Heo <tj@kernel.org>
To: Doug Anderson <dianders@chromium.org>
Cc: David Vernet <void@manifault.com>,
	linux-kernel@vger.kernel.org, kernel-team@meta.com,
	sched-ext@meta.com, Andrea Righi <arighi@nvidia.com>,
	Changwoo Min <multics69@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH sched_ext/for-6.13 2/2] sched_ext: Enable the ops breather and eject BPF scheduler on softlockup
Date: Wed, 6 Nov 2024 13:07:51 -1000	[thread overview]
Message-ID: <Zyv2x6kb3gO8cTO7@slm.duckdns.org> (raw)
In-Reply-To: <CAD=FV=UTh=JGUDZxO74+ZRQbF+yzcWnBo-f=oie0msmBn2_00g@mail.gmail.com>

Hello,

On Wed, Nov 06, 2024 at 03:02:35PM -0800, Doug Anderson wrote:
...
> Honestly, it would feel better to me if the soft lockup timer didn't
> tell schedext to kill things but instead we just make some special
> exception for "schedext" tasks and exclude them from the softlockup
> detector because they're already being watched by their own watchdog.
> Would that be possible? Then tweaking the "softlockup" timeouts
> doesn't implicitly change how long schedext things can run.

Some systems can get into full blown live-lock condition where CPUs are
barely making forward progress through the scheduler and all normal (!RT &&
!DEADLINE) tasks are on sched_ext, so the only reasonable way to exclude
sched_ext would be disabling softlockup detection while sched_ext is
enabled which doesn't feel like a sound trade-off.

Thanks.

-- 
tejun

  reply	other threads:[~2024-11-06 23:07 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-11-05 21:48 [PATCH sched_ext/for-6.13 1/2] sched_ext: Avoid live-locking bypass mode switching Tejun Heo
2024-11-05 21:49 ` [PATCH sched_ext/for-6.13 2/2] sched_ext: Enable the ops breather and eject BPF scheduler on softlockup Tejun Heo
2024-11-06 21:32   ` Doug Anderson
2024-11-06 22:08     ` Tejun Heo
2024-11-06 23:02       ` Doug Anderson
2024-11-06 23:07         ` Tejun Heo [this message]
2024-11-06 23:20           ` Doug Anderson
2024-11-07 19:31             ` Tejun Heo
2024-11-08 20:38   ` Tejun Heo
2024-11-05 22:03 ` [PATCH sched_ext/for-6.13 1/2] sched_ext: Avoid live-locking bypass mode switching David Vernet
2024-11-05 23:02   ` Tejun Heo
2024-11-05 23:57 ` Andrea Righi
2024-11-06  0:26   ` Tejun Heo
2024-11-06  0:33     ` Andrea Righi

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