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Message-ID: <2a424df7-8114-477e-ab5c-484d2ed8d9a4@kernel.dk>
Date: Wed, 11 Sep 2024 10:28:14 -0600
From: Jens Axboe <axboe@...nel.dk>
To: Felix Moessbauer <felix.moessbauer@...mens.com>
Cc: stable@...r.kernel.org, asml.silence@...il.com,
linux-kernel@...r.kernel.org, io-uring@...r.kernel.org,
cgroups@...r.kernel.org, dqminh@...udflare.com, longman@...hat.com,
adriaan.schmidt@...mens.com, florian.bezdeka@...mens.com
Subject: Re: [PATCH 6.1 0/2] io_uring/io-wq: respect cgroup cpusets
On 9/11/24 10:23 AM, Felix Moessbauer wrote:
> Hi,
>
> as discussed in [1], this is a manual backport of the remaining two
> patches to let the io worker threads respect the affinites defined by
> the cgroup of the process.
>
> In 6.1 one worker is created per NUMA node, while in da64d6db3bd3
> ("io_uring: One wqe per wq") this is changed to only have a single worker.
> As this patch is pretty invasive, Jens and me agreed to not backport it.
>
> Instead we now limit the workers cpuset to the cpus that are in the
> intersection between what the cgroup allows and what the NUMA node has.
> This leaves the question what to do in case the intersection is empty:
> To be backwarts compatible, we allow this case, but restrict the cpumask
> of the poller to the cpuset defined by the cgroup. We further believe
> this is a reasonable decision, as da64d6db3bd3 drops the NUMA awareness
> anyways.
>
> [1] https://lore.kernel.org/lkml/ec01745a-b102-4f6e-abc9-abd636d36319@kernel.dk
The upstream patches are staged for 6.12 and marked for a backport, so
they should go upstream next week. Once they are upstream, I'll make
sure to check in on these on the stable front.
--
Jens Axboe
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