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From: Thomas Gleixner <tglx@linutronix.de>
To: Ming Lei <ming.lei@redhat.com>, Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <kbusch@kernel.org>, Keith Busch <kbusch@meta.com>,
 linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, Frederic
 Weisbecker <frederic@kernel.org>
Subject: Re: [PATCH 2/2] nvme-pci: allow unmanaged interrupts
In-Reply-To: <ZkwHnw6HkGFFq7mR@fedora>
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Date: Tue, 21 May 2024 10:38:25 +0200
Message-ID: <87a5kjimpq.ffs@tglx>
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On Tue, May 21 2024 at 10:31, Ming Lei wrote:

> On Mon, May 20, 2024 at 05:37:42PM +0200, Christoph Hellwig wrote:
>> On Sun, May 12, 2024 at 08:35:55AM +0200, Thomas Gleixner wrote:
>> > That's expected as you pin the I/O operation on the isolated CPUs which
>> > in turn makes them use the per CPU queue.
>> > 
>> > The isolated CPUs are only excluded for device management interrupts,
>> > but not for the affinity spread of the queues.
>> 
>> We'll probably need a version of isolcpus that also excludes the
>> interrupt spread given that users are asking for it.  And I'd much
>> prefer that over adding radom module options to every driver to disable
>> managed interrupts.
>
> BTW, isolcpus has been marked as deprecated, and it can't be adjust
> runtime.

Which is far from reality as cpusets do not allow to do what isolcpus
does today.

Also runtime adjusting managed interrupts needs way more thoughts.

Thanks

        tglx