linux-kernel - Re: [Question] Include isolated cpu to ensure that tasks are not scheduled to isolated cpu？

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Message-ID: <cb3a3f3e-727a-4cbb-b4a8-f9469ed4f08d@redhat.com>
Date: Sun, 1 Sep 2024 23:00:16 -0400
From: Waiman Long <longman@...hat.com>
To: zhengzucheng <zhengzucheng@...wei.com>, peterz@...radead.org,
 juri.lelli@...hat.com, vincent.guittot@...aro.org, dietmar.eggemann@....com,
 rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
 vschneid@...hat.com, oleg@...hat.com,
 Frederic Weisbecker <frederic@...nel.org>, mingo@...nel.org,
 peterx@...hat.com, tj@...nel.org
Cc: linux-kernel@...r.kernel.org
Subject: Re: [Question] Include isolated cpu to ensure that tasks are not scheduled to isolated cpu？

On 9/1/24 21:56, zhengzucheng wrote:
> In a cpuset subsystem, cpuset.cpus contains isolated cpu and 
> non-isolated cpu.
> Is there any way to ensure that the task runs only on the non-isolated 
> cpus?
> eg：
> isolcpus=1, cpusete.cpus=0-7. It is found that some tasks are 
> scheduled to cpu1.
>
> In addition, task run on isolated cpu cann't be scheduled to other cpu 
> in the future.

The best way is to avoid mixing isolated and scheduling CPUs in the same 
cpuset especially if you are using cgroup v1.

If you are using cgroup v2, one way to avoid the use of isolated CPUs is 
to put all of them into an isolated partition. This will ensure that 
those isolated CPUs won't be used even if they are put into the 
cpuset.cpus of other cpusets accidentally

Cheers,
Longman