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From: Thomas Gleixner <tglx@linutronix.de>
To: Costa Shulyupin <costa.shul@redhat.com>
Cc: longman@redhat.com, pauld@redhat.com, linux-kernel@vger.kernel.org, Ming
 Lei <ming.lei@redhat.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v1 4/7] sched/isolation: Adjust affinity of managed irqs
 according to change of housekeeping cpumask
In-Reply-To: <CADDUTFx4XPtAYNUPK03BSFH0p8Z17OCftEb7aq+f6VqpnEWkoA@mail.gmail.com>
References: <20240516190437.3545310-1-costa.shul@redhat.com>
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 <87seyfj4h7.ffs@tglx>
 <CADDUTFx4XPtAYNUPK03BSFH0p8Z17OCftEb7aq+f6VqpnEWkoA@mail.gmail.com>
Date: Mon, 27 May 2024 17:31:48 +0200
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On Mon, May 27 2024 at 15:21, Costa Shulyupin wrote:
> Thank you so much for very valuable feedback!
> I've tested your proposal to use the hotplug for the isolation.
> It works well for both timers, but managed irqs are not ready for this scenario.
>
> How do you suggest to proceed?

That's non-trivial because it's not only the interrupt affinity.

Drivers also have their queues associated accordingly and if you just
change the interrupt affinity under the hood then all the other
associations don't get updated and don't work.

That needs to be solved at some other level IMO.

Thanks,

        tglx