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

luca abeni
2025-05-20T16:09:23Z

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.

So, since you are seeing unexpected deadline misses, there is a bug
somewhere... I am going to check.
In the meantime, enjoy the Cretan wilderness :)

Luca