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Message-ID: <20130513084008.GO11497@suse.de>
Date: Mon, 13 May 2013 09:40:08 +0100
From: Mel Gorman <mgorman@...e.de>
To: PINTU KUMAR <pintu_agarwal@...oo.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [Query] Performance degradation with memory compaction (on QC
chip-set)
On Sun, May 12, 2013 at 08:00:26PM -0700, PINTU KUMAR wrote:
> Dear Mel Gorman,
>
> I have one question about memory compaction.
> Kernel version: kernel-3.4 (ARM)
> Chipset: Qual-Comm MSM8930 dual-core.
>
> We wanted to enable CONFIG_COMPACTION for our product with kernel-3.4.
> But QC commented that, enabling compaction on their chip-set is causing performance degradation for some streaming scenarios (from the beginning).
>
> I wanted to know is this possible always?
> We used compaction with exynos processor and did not observe any performance degradation.
>
I suspect one of their drivers are using high-order allocations and
hitting compaction as a result. Compaction is not guaranteed to cause
overhead but if it's in use then the scanning and copying overhead can
cause problems.
> Please let me know your comments.
> It will be helpful to decide on enabling compaction or not.
>
Depends on workload and drivers.
--
Mel Gorman
SUSE Labs
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