From: Peter Zijlstra <peterz@infradead.org>
To: Radoslaw Zielonek <radoslaw.zielonek@gmail.com>
Cc: mingo@redhat.com, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
bristot@redhat.com, vschneid@redhat.com, oleg@redhat.com,
brauner@kernel.org, akpm@linux-foundation.org,
tandersen@netflix.com, bigeasy@linutronix.de,
vincent.whitchurch@axis.com, kunyu@nfschina.com, ardb@kernel.org,
linux-kernel@vger.kernel.org, liam.howlett@oracle.com,
syzbot+a941018a091f1a1f9546@syzkaller.appspotmail.com,
syzkaller-bugs@googlegroups.com
Subject: Re: [RFC] Signaling overhead on RT tasks is causing RCU stall
Date: Fri, 5 Jul 2024 10:10:52 +0200 [thread overview]
Message-ID: <20240705081052.GA11386@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20240705075622.925325-2-radoslaw.zielonek@gmail.com>
On Fri, Jul 05, 2024 at 09:56:23AM +0200, Radoslaw Zielonek wrote:
> Hello,
>
> I'm working on syzbot bug: rcu detected stall in validate_mm
> https://syzkaller.appspot.com/bug?extid=a941018a091f1a1f9546.
> I have analyzed this issue and here is what I found:
>
> When too many signals are sent to the RT task, the overhead becomes very high.
> The task cannot perform its job and as a consquenece the rt_runtime (0.95s)
> is not reached even after hundreds of seconds.
I'm having trouble parsing this. What overhead becomes high? Is the task
spending time in-kernel? Because if the task is spending time in-user
handling all its signals, it should accumulate runtime just fine.
That is, your analysis seems to leave out / gloss over the important
bit.
next prev parent reply other threads:[~2024-07-05 8:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-05 7:56 [RFC] Signaling overhead on RT tasks is causing RCU stall Radoslaw Zielonek
2024-07-05 8:10 ` Peter Zijlstra [this message]
2024-07-09 7:43 ` Radoslaw Zielonek
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