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Subject: Re: Abysmal scheduler performance in Linus' tree?
From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Date: Thu, 07 Sep 2017 08:15:29 +0200
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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.

	-Mike

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