[systemd-devel] machined: after CPU offline then online, vcpupin KVM guest failed to start

[Lennart Poettering]

On Fri, 05.08.16 12:33, Dr. Werner Fink (werner at suse.de) wrote:

> > Yeah, to make this clear: I do not blame libvirt for this borkedness
> > at all. I blame the kernel.
> 
> Hmmm ... IMHO it is useless to pass the buck from kernel to user space
> as well do the same from user space back to kernel.  I've an open bug
> from a customer and this bug requires a solution.  AFAICS libvirt can
> not do this but machined could do.

machined certainly can't. It doesn't do cgroup stuff at all. It just
keeps tracks of local containers and VMs. cgroup management is done by
systemd in PID1 itself. So no, machined certainly can't.

And in systemd itself we are very conservative on working around
broken kernel behaviour. Note that Tejun (the kernel's cgroup
maintainer) actually acknowledges that cpuset has broken semantics
there.

For many cases CPUAffinity= is actually enough, not for all, if you
need a quick solution.

If you require the correct solution, please work with Tejun to fix the
cpuset semantics and as that has happened we can start making use of
this in systemd.

Lennart

-- 
Lennart Poettering, Red Hat