Re: SCHED_DEADLINE tasks missing their deadline with SCHED_FLAG_RECLAIM jobs in the mix (using GRUB)

Marcel Ziswiler
2025-05-21T10:25:40Z

Hi Luca

On Tue, 2025-05-20 at 18:09 +0200, luca abeni wrote:
> Hi Marcel,
>
> On Mon, 19 May 2025 15:32:27 +0200
> Marcel Ziswiler <marcel.ziswiler@codethink.co.uk> wrote:
>
> > Hi Luca
> >
> > Thanks and sorry, for my late reply. I was traveling the Cretan
> > wilderness without access to any work related infrastructure.
> >
> > On Wed, 2025-05-07 at 22:25 +0200, luca abeni wrote:
> > > Hi Marcel,
> > >
> > > just a quick question to better understand your setup (and check
> > > where the issue comes from):
> > > in the email below, you say that tasks are statically assigned to
> > > cores; how did you do this? Did you use isolated cpusets,
> >
> > Yes, we use the cpuset controller from the cgroup-v2 APIs in the
> > linux kernel in order to partition CPUs and memory nodes. In detail,
> > we use the AllowedCPUs and AllowedMemoryNodes in systemd's slice
> > configurations.
>
> OK, I never tried the v2 API, but if it allows creating a new root
> domain (which is an isolated cpuset, I think), then it should work
> without issues.

Yes and it works fine with everything else :)

> So, since you are seeing unexpected deadline misses, there is a bug
> somewhere... I am going to check.

Thanks you very much and let me know if you need any further information figuring out what might be going on.

> In the meantime, enjoy the Cretan wilderness :)

Thanks, I already made it back and, yes, I enjoyed it very much :)

> Luca

Cheers

Marcel