* Re: [PATCH v7 4/4] workqueue: Unbind kworkers before sending them to exit()
[not found] ` <20230109133316.4026472-5-vschneid@redhat.com>
@ 2023-01-11 3:33 ` Hillf Danton
0 siblings, 0 replies; only message in thread
From: Hillf Danton @ 2023-01-11 3:33 UTC (permalink / raw)
To: Valentin Schneider
Cc: linux-kernel, Tejun Heo, Lai Jiangshan, Peter Zijlstra,
Frederic Weisbecker, linux-mm, Marcelo Tosatti
On 9 Jan 2023 13:33:16 +0000 Valentin Schneider <vschneid@redhat.com>
> It has been reported that isolated CPUs can suffer from interference due to
> per-CPU kworkers waking up just to die.
>
> A surge of workqueue activity during initial setup of a latency-sensitive
> application (refresh_vm_stats() being one of the culprits) can cause extra
> per-CPU kworkers to be spawned. Then, said latency-sensitive task can be
> running merrily on an isolated CPU only to be interrupted sometime later by
> a kworker marked for death (cf. IDLE_WORKER_TIMEOUT, 5 minutes after last
> kworker activity).
Given no scheduling in userspace, how is the latency-sensitive task interrupted
by woken kworker?
If it is due to wakeup preempt then disabling it on isolated CPU for user mode
makes more sense, but that should add change to scheduler instead.
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[not found] ` <20230109133316.4026472-5-vschneid@redhat.com>
2023-01-11 3:33 ` [PATCH v7 4/4] workqueue: Unbind kworkers before sending them to exit() Hillf Danton
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