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.