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Date:   Wed, 12 Apr 2023 20:26:03 -0400
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Subject: Re: [RFC PATCH 0/5] cgroup/cpuset: A new "isolcpus" paritition
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To:     Tejun Heo <tj@kernel.org>
Cc:     Zefan Li <lizefan.x@bytedance.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Shuah Khan <shuah@kernel.org>, linux-kernel@vger.kernel.org,
        cgroups@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kselftest@vger.kernel.org,
        Juri Lelli <juri.lelli@redhat.com>,
        Valentin Schneider <vschneid@redhat.com>,
        Frederic Weisbecker <frederic@kernel.org>
References: <20230412153758.3088111-1-longman@redhat.com>
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From:   Waiman Long <longman@redhat.com>
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On 4/12/23 20:03, Tejun Heo wrote:
> Hello,
>
> On Wed, Apr 12, 2023 at 04:33:29PM -0400, Waiman Long wrote:
>> I think we can. You mean having a new "cpuset.cpus.isolated" cgroupfs file.
>> So there will be one in the root cgroup that defines all the isolated CPUs
>> one can have. It is then distributed down the hierarchy and can be claimed
>> only if a cgroup becomes an "isolated" partition. There will be a slight
> Yeah, that seems a lot more congruent with the typical pattern.
>
>> change in the semantics of an "isolated" partition, but I doubt there will
>> be much users out there.
> I haven't thought through it too hard but what prevents staying compatible
> with the current behavior?

It is possible to stay compatible with existing behavior. It is just 
that a break from existing behavior will make the solution more clean.

So the new behavior will be:

   If the "cpuset.cpus.isolated" isn't set, the existing rules applies. 
If it is set, the new rule will be used.

Does that look reasonable to you?

Cheers,
Longman