linux-kernel - Re: [patch v2 0/3] mm: improve page aging fairness between zones/nodes

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Date:	Fri, 2 Aug 2013 21:59:59 +0200
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...riel.com>,
	Zlatko Calusic <zcalusic@...sync.net>,
	Minchan Kim <minchan@...nel.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [patch v2 0/3] mm: improve page aging fairness between
 zones/nodes

On Fri, Aug 02, 2013 at 11:37:23AM -0400, Johannes Weiner wrote:
> Changes in version 2:

v2 looks great to me.

                zone->alloc_batch -= 1U << order;
    3147:       d3 e0                   shl    %cl,%eax
    3149:       29 42 54                sub    %eax,0x54(%rdx)

gcc builds it as one asm insn too.

Considering we depend on gcc to be optimal and to update ptes in a
single insn (and if it doesn't we'll corrupt memory), keeping it in C
should always provide the update in a single insn.

I believe the error introduced when mulptiple CPUs of the same NUMA
node step on each other is going to be unmeasurable.

ACK the whole series.

Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>

Thanks,
Andrea
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