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Date: Wed, 3 Apr 2024 11:10:37 -0400
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Subject: Re: [PATCH 1/2] cgroup/cpuset: Make cpuset hotplug processing
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To: =?UTF-8?Q?Michal_Koutn=C3=BD?= <mkoutny@suse.com>
Cc: Valentin Schneider <vschneid@redhat.com>, Tejun Heo <tj@kernel.org>,
 Zefan Li <lizefan.x@bytedance.com>, Johannes Weiner <hannes@cmpxchg.org>,
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 "Rafael J. Wysocki" <rafael@kernel.org>, Len Brown <len.brown@intel.com>,
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 Frederic Weisbecker <frederic@kernel.org>,
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 Anna-Maria Behnsen <anna-maria@linutronix.de>, Alex Shi <alexs@kernel.org>,
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From: Waiman Long <longman@redhat.com>
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On 4/3/24 10:56, Michal Koutný wrote:
> On Wed, Apr 03, 2024 at 10:47:33AM -0400, Waiman Long <longman@redhat.com> wrote:
>> should be rare these days as it will only apply in the case of cgroup
>> v1 under certain condtion,
> Could the migration be simply omitted it those special cases?
>
> (Tasks remain in cpusets with empty cpusets -- that already happens in
> with the current patch before workqueue is dispatched.)

The tasks should not be runnable if there is no CPUs left in their v1 
cpuset. Migrating them to a parent with runnable CPUs is the current way 
which I don't want to break. Alternatively, we could force it to fall 
back to cgroup v2 behavior using the CPUs in their parent cpuset.

Cheers,
Longman

>
> Michal