linux-kernel - Re: [PATCH 09/17] sched/core: Add support for nohz

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Message-ID: <ce4a239b-271c-415f-81d1-ef8360f3fd09@amd.com>
Date: Mon, 24 Nov 2025 10:06:06 +0530
From: K Prateek Nayak <kprateek.nayak@....com>
To: Shrikanth Hegde <sshegde@...ux.ibm.com>, <linux-kernel@...r.kernel.org>,
	<linuxppc-dev@...ts.ozlabs.org>
CC: <mingo@...hat.com>, <peterz@...radead.org>, <juri.lelli@...hat.com>,
	<vincent.guittot@...aro.org>, <tglx@...utronix.de>, <yury.norov@...il.com>,
	<maddy@...ux.ibm.com>, <srikar@...ux.ibm.com>, <gregkh@...uxfoundation.org>,
	<pbonzini@...hat.com>, <seanjc@...gle.com>, <vschneid@...hat.com>,
	<iii@...ux.ibm.com>, <huschle@...ux.ibm.com>, <rostedt@...dmis.org>,
	<dietmar.eggemann@....com>, <christophe.leroy@...roup.eu>
Subject: Re: [PATCH 09/17] sched/core: Add support for nohz_full CPUs

Hello Shrikanth,

On 11/21/2025 10:10 AM, Shrikanth Hegde wrote:
>> Wouldn't the task be pinned if it is running on a nohz CPU?
>> We don't push out pinned tasks so this seems unnecessary.
>> Am I missing something?
>>
> 
> No. Task will not be pinned if it running on nohz_full unless
> user has done a taskset. They are still part of sched domains.
> 
> Pinning is usually true for isolcpus. You need to explicity set taskset
> for isolcpus since by default you won't go to those CPUs.

TIL! I was under the impression that nohz_full is a superset of isolcpus
but I was clearly mistaken. Thank you for clarifying.

-- 
Thanks and Regards,
Prateek