Re: Abysmal scheduler performance in Linus' tree?

From: Ingo Molnar
Date: Thu Sep 07 2017 - 03:31:46 EST



* Mike Galbraith <efault@xxxxxx> wrote:

> On Wed, 2017-09-06 at 18:14 +0200, Peter Zijlstra wrote:
> > On Wed, Sep 06, 2017 at 11:03:33AM +0200, Peter Zijlstra wrote:
> > > On Wed, Sep 06, 2017 at 01:59:14AM -0700, Andy Lutomirski wrote:
> > > > > Any specifics on your setup?
> > > >
> > > > On further fiddling, I only see this after a suspend and resume cycle.
> > >
> > > Ah, ok. That's not something I otherwise test. Lets see if I can force
> > > this brick of mine through a suspend-resume cycle :-)
> >
> > I'd be suspicious of these here commits:
> >
> > 77d1dfda0e79 ("sched/topology, cpuset: Avoid spurious/wrong domain rebuilds")
>
> Seems to be that one.  After suspend/resume, cpu7 (i4790+SMT) is online
> with NULL domain.  offline/online it, it grows proper domains.

Thanks, that's really useful, should narrow things down!

> (on vacation, about to go explore that unfamiliar 'outside' place)  

Be careful, it's a dangerous world for kernel hackers! ;-)

Thanks,

Ingo