linux-kernel - Re: [tip:sched/numa] mm/mpol: Lazy migrate a process/vma

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Message-ID: <m2r4ud86uw.fsf@firstfloor.org>
Date:	Mon, 21 May 2012 16:14:15 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	mingo@...nel.org
Cc:	hpa@...or.com, linux-kernel@...r.kernel.org,
	a.p.zijlstra@...llo.nl, torvalds@...ux-foundation.org,
	pjt@...gle.com, cl@...ux.com, riel@...hat.com,
	bharata.rao@...il.com, akpm@...ux-foundation.org,
	Lee.Schermerhorn@...com, aarcange@...hat.com, danms@...ibm.com,
	suresh.b.siddha@...el.com, tglx@...utronix.de,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:sched/numa] mm/mpol: Lazy migrate a process/vma

tip-bot for Peter Zijlstra <a.p.zijlstra@...llo.nl> writes:
> +
> +	/*
> +	 * Obtain a more-or-less correct nodemask to find which pages we need
> +	 * to unmap so that MoF can put them right again.
> +	 *
> +	 * Not quite correct for INTERLEAVE, that would need us doing
> +	 * offset_il_node() from check_pte_entry().
> +	 *
> +	 * Also not quite correct for task policies since we don't have a task,
> +	 * approximate by having @node function as local / task-home-node.

Hmm, so this destroys existing numa policies for already running processes?

Andrea's original THP had a similar problem, and it caused serious
performance problems before it was fixed.

I also seem to miss the benchmark numbers justifying all that code.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only
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