Re: stalling IO regression in linux 5.12

[Josef Bacik <josef@toxicpanda.com>]

On Wed, Aug 10, 2022 at 02:42:40PM -0400, Chris Murphy wrote:
> 
> 
> On Wed, Aug 10, 2022, at 2:33 PM, Chris Murphy wrote:
> > On Wed, Aug 10, 2022, at 1:48 PM, Josef Bacik wrote:
> >
> >> To help narrow this down can you disable any IO controller you've got enabled
> >> and see if you can reproduce?  If you can sysrq+w is super helpful as it'll
> >> point us in the next direction to look.  Thanks,
> >
> > I'm not following, sorry. I can boot with 
> > systemd.unified_cgroup_hierarchy=0 to make sure it's all off, but we're 
> > not using an IO cgroup controllers specifically as far as I'm aware.
> 
> OK yeah that won't work because the workload requires cgroup2 or it won't run.
>

Oh no I don't want cgroups completley off, just disable the io controller, so
figure out which cgroup your thing is being run in, and then

echo "-io" > <parent dir>/cgroup.subtree_control

If you cat /sys/fs/cgroup/whatever/cgroup/cgroup.controllers and you see "io" in
there keep doing the above in the next highest parent directory until io is no
longer in there.  Thanks,

Josef