linux-kernel - Re: question on NUMA page migration

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Message-ID: <20121020012345.GA24667@gmail.com>
Date:	Sat, 20 Oct 2012 03:23:46 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Rik van Riel <riel@...hat.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Linux Memory Management List <linux-mm@...ck.org>,
	Mel Gorman <mel@....ul.ie>,
	Linux kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: question on NUMA page migration


* Rik van Riel <riel@...hat.com> wrote:

> On 10/19/2012 01:53 PM, Peter Zijlstra wrote:
> >On Fri, 2012-10-19 at 13:13 -0400, Rik van Riel wrote:
> 
> >>Another alternative might be to do the put_page inside
> >>do_prot_none_numa().  That would be analogous to do_wp_page
> >>disposing of the old page for the caller.
> >
> >It'd have to be inside migrate_misplaced_page(), can't do before
> >isolate_lru_page() or the page might disappear. Doing it after is
> >(obviously) too late.
> 
> Keeping an extra refcount on the page might _still_
> result in it disappearing from the process by some
> other means, in-between you grabbing the refcount
> and invoking migration of the page.
> 
> >>I am not real happy about NUMA migration introducing its own
> >>migration mode...
> >
> >You didn't seem to mind too much earlier, but I can remove it if you
> >want.
> 
> Could have been reviewing fatigue :)

:-)

> And yes, it would have been nice to not have a special
> migration mode for sched/numa.
> 
> Speaking of, when do you guys plan to submit a (cleaned up)
> version of the sched/numa patch series for review on lkml?

Which commit(s) worry you specifically?

Thanks,

	Ingo
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