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Date: Sat, 31 Jul 2010 21:09:35 +0300
Message-ID: <AANLkTikG7UOSh=iH02YwO0ihpu2waKt3bHH7LLK-33MP@mail.gmail.com>
Subject: Re: [PATCH] vmscan: raise the bar to PAGEOUT_IO_SYNC stalls
From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Christoph Hellwig <hch@infradead.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>, stable@kernel.org,
        Rik van Riel <riel@redhat.com>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Mel Gorman <mel@csn.ul.ie>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        Dave Chinner <david@fromorbit.com>,
        Chris Mason <chris.mason@oracle.com>, Nick Piggin <npiggin@suse.de>,
        Johannes Weiner <hannes@cmpxchg.org>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Minchan Kim <minchan.kim@gmail.com>, Andreas Mohr <andi@lisas.de>,
        Bill Davidsen <davidsen@tmr.com>, Ben Gamari <bgamari.foss@gmail.com>,
        Christoph Lameter <cl@linux-foundation.org>
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On Sat, Jul 31, 2010 at 8:59 PM, Christoph Hellwig <hch@infradead.org> wrote:
> On Sat, Jul 31, 2010 at 08:55:57PM +0300, Pekka Enberg wrote:
>> Do you have CONFIG_SLUB enabled? It does high order allocations by
>> default for performance reasons.
>
> Yes. This is a kernel using slub.

You can pass "slub_debug=o" as a kernel parameter to disable higher
order allocations if you want to test things. The per-cache default
order is calculated in calculate_order() of mm/slub.c. How many CPUs
do you have on your system?
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