linux-kernel - Re: [PATCH 6.1 0/2] io_uring/io-wq: respect cgroup cpusets

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Message-ID: <2024093053-gradient-errant-4f54@gregkh>
Date: Mon, 30 Sep 2024 21:15:23 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Felix Moessbauer <felix.moessbauer@...mens.com>
Cc: axboe@...nel.dk, 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 Wed, Sep 11, 2024 at 06:23:14PM +0200, 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

Why was neither of these actually tagged for inclusion in a stable tree?
Why just 6.1.y?  Please submit them for all relevent kernel versions.

thanks,

greg k-h