From: Tejun Heo <tj@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
K Prateek Nayak <kprateek.nayak@amd.com>,
Kyle McMartin <jkkm@meta.com>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Linux RT Development <linux-rt-devel@lists.linux.dev>,
Clark Williams <williams@redhat.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
John Kacur <jkacur@redhat.com>
Subject: Re: [PATCH sched/core] sched/rt: Fix RT_PUSH_IPI soft lockup loop
Date: Wed, 13 May 2026 18:48:31 -1000 [thread overview]
Message-ID: <agVUH-L503DwAiSW@slm.duckdns.org> (raw)
In-Reply-To: <20260513220136.5a11c740@fedora>
Hello,
On Wed, May 13, 2026 at 10:01:36PM -0400, Steven Rostedt wrote:
> I could try, but there are still some things that I don't understand.
> One is that to send more IPIs due to the RT pull request, there needs
> to be RT tasks constantly sleeping. Is that happening in this use case?
> Are the softirqs waking up RT tasks that run for a short time and go
> back to sleep, causing the pull IPI to trigger again?
Ah, yes, that makes sense. That's why the repro is using FIFO threads too.
In prod, there's mpi3mr threaded irq handlers that are FIFO. These are
storage machines so they're also constantly active.
Thanks.
--
tejun
next prev parent reply other threads:[~2026-05-14 4:48 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-06 23:57 [PATCH sched/core] sched/rt: Fix RT_PUSH_IPI soft lockup loop Tejun Heo
2026-05-07 14:14 ` Peter Zijlstra
2026-05-11 19:33 ` Tejun Heo
2026-05-12 15:37 ` Steven Rostedt
2026-05-12 18:07 ` Tejun Heo
2026-05-12 21:28 ` Steven Rostedt
2026-05-13 19:39 ` Tejun Heo
2026-05-14 0:24 ` Steven Rostedt
2026-05-14 0:53 ` Tejun Heo
2026-05-14 1:31 ` Steven Rostedt
2026-05-14 1:42 ` Tejun Heo
2026-05-14 2:01 ` Steven Rostedt
2026-05-14 4:48 ` Tejun Heo [this message]
2026-05-12 20:10 ` Valentin Schneider
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