Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH -tip V3 0/8] workqueue: break affinity initiatively | Date | Mon, 11 Jan 2021 11:07:34 +0100 |
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On Fri, Jan 08 2021 at 12:46, Peter Zijlstra wrote: > On Sat, Dec 26, 2020 at 10:51:08AM +0800, Lai Jiangshan wrote: >> From: Lai Jiangshan <laijs@linux.alibaba.com> >> >> 06249738a41a ("workqueue: Manually break affinity on hotplug") >> said that scheduler will not force break affinity for us. > > So I've been looking at this the past day or so, and the more I look, > the more I think commit: > > 1cf12e08bc4d ("sched/hotplug: Consolidate task migration on CPU unplug") > > is a real problem and we need to revert it (at least for now). > > Let me attempt a brain dump: > > - the assumption that per-cpu kernel threads are 'well behaved' on > hot-plug has, I think, been proven incorrect, it's far worse than > just bounded workqueue. Therefore, it makes sense to provide the old > semantics.
I disagree. Per-cpu kernel threads which are magically stopped during hotplug and then migrated to a random other CPU are just wrong.
We really need to fix that and not proliferate the sloppy and ill defined behaviour.
Thanks,
tglx
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