Re: [PATCH v5 2/2] nvme-tcp: allow setting per-queue io_cpu through sysfs

[Daniel Wagner]

On Wed, Oct 21, 2026 at 09:21:09AM +0200, Hannes Reinecke wrote:
> > I think it make sense to allow that the user can change queue CPU
> > pinning during runtime even with isolcpu enabled. And then the question
> > is should this be connected to cgroups?
> 
> Not sure if cgroups is the right concept here; cgroups are user/
> application centric whereas nvme-tcp is pretty much queue/cpu centric.
> IE after all the cgroup calculations are done.
> Don't think cgroups are a good fit here.

There was a lot of discussion during Linux Plumbers on how to configure
a system for the isolcpus case at runtime. From what I understand, the
preferred interface for this is cgroups. Hence, pinning the CPU for this
work is likely a target for it, though I don't think there is a need to
figure it out right now. I just wanted to highlight this point.

However, to make this truly user-friendly, I think nvme-cli should be
extended so it is aware of this and can configure it directly. I've
merged Nilay's --nr-io-queues patches, so this is the natural next
feature nvme-cli should support; see commit:

e170d6985797 ("news: document the use of --nr-io-queues during nvme connect")

I would also really like to have a blktest for this as well.