linux-kernel - Re: [PATCH] MTD: Retry Read/Write Transfer Buffer Allocations

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Date:	Mon, 04 Apr 2011 10:41:50 +0300
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Grant Erickson <marathon96@...il.com>
Cc:	linux-mtd@...ts.infradead.org,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] MTD: Retry Read/Write Transfer Buffer Allocations

On Mon, 2011-04-04 at 10:27 +0300, Artem Bityutskiy wrote:
> An third, as I wrote in my answer to Jarkko, allocating large contiguous
> buffers is bad for performance: if the system memory is fragmented and
> there is no such large contiguous areas, the kernel will start writing
> back dirty FS data, killing FS caches, shrinking caches and buggers,
> probably even swapping out applications. We do not want MTD to cause
> this at all.

s/buggers/buffers/

> Probably we can mitigate this with kmalloc flags. Now, I'm not sure what
> flags are the optimal, but I'd do:
> 
> __GFP_NOWARN | __GFP_WAIT | __GFP_NORETRY

Of course I meant you should use special flags as long as you are
allocating more than 1 contiguous page. But the last PAGE_SIZE
allocation should be done with standard GFP_KERNEL flag.

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)

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