linux-kernel - Re: [RFC PATCH v3 2/4] sched/rt: add support for parked CPUs

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Message-ID: <a56f71e2-fad3-4777-b774-a43bc6fabcac@linux.ibm.com>
Date: Mon, 12 May 2025 17:16:21 +0200
From: Tobias Huschle <huschle@...ux.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...hat.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, sshegde@...ux.ibm.com
Subject: Re: [RFC PATCH v3 2/4] sched/rt: add support for parked CPUs



On 12/05/2025 13:53, Tobias Huschle wrote:
> Realtime tasks must also react to the parked states of CPUs. Tasks will
> be treated as if the parked CPUs have no free capacity to work on them.
> 
> A dynamic change in the parked state of CPUs is handled correctly if
> realtime tasks do not consume 100% CPU time, without any interruption.
> If a realtime tasks runs without interruption, it will never enter the
> load balancing code and will therefore remain on a CPU, even if the CPU
> becomes classified as parked. Any value below 100% causes the task to
> be migrated off a CPU which has just been classified as parked.
> 
> Signed-off-by: Tobias Huschle <huschle@...ux.ibm.com>

The content of this patch was proposed by Shrikanth, so special thanks 
to him!

<...>