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Date: Tue, 21 Jun 2016 21:47:19 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Tejun Heo <htejun@gmail.com>
Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Abdul Haleem <abdhalee@linux.vnet.ibm.com>,
        Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>,
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Subject: Re: [PATCH 1/2] workqueue: Move wq_update_unbound_numa() to the
 beginning of CPU_ONLINE
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On Tue, Jun 21, 2016 at 03:43:56PM -0400, Tejun Heo wrote:
> On Tue, Jun 21, 2016 at 09:37:09PM +0200, Peter Zijlstra wrote:
> > Hurm.. So I've applied it, just to get this issue sorted, but I'm not
> > entirely sure I like it.
> > 
> > I think I prefer ego's version because that makes it harder to get stuff
> > to run on !active,online cpus. I think we really want to be careful what
> > gets to run during that state.
> 
> The original patch just did set_cpus_allowed one more time late enough
> so that the target kthread (in most cases) doesn't have to go through
> fallback rq selection afterwards.  I don't know what the long term
> solution is but CPU_ONLINE callbacks should be able to bind kthreads
> to the new CPU one way or the other.

Fair enough; clearly I need to stare harder. In any case, patch is on
its way to sched/urgent.