linux-kernel - Re: [PATCH] mm: raise MemFree by reverting percpu_pagelist

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Message-ID: <CA+1xoqc15HY1rECsJ6Aj1WMzwT12z4DByJhFopyBAiKawEFh3Q@mail.gmail.com>
Date:	Fri, 11 May 2012 18:35:00 +0200
From:	Sasha Levin <levinsasha928@...il.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Minchan Kim <minchan@...nel.org>, Hugh Dickins <hughd@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: raise MemFree by reverting percpu_pagelist_fraction
 to 0

On Fri, May 11, 2012 at 6:27 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> On Fri, May 11, 2012 at 2:01 AM, Minchan Kim <minchan@...nel.org> wrote:
>>
>> I didn't have a time so made quick patch to show just concept.
>> Not tested and Not consider carefully.
>> If anyone doesn't oppose, I will send formal patch which will have more beauty code.
>
> What's so magical about that '8' *anyway*? We do we have that minimum at all?
>
> At the very least, the 8-vs-0 thing needs to be explained.

The '0' acts as an "off" switch.

Once it's on, we reserve 1/x of the pages for the pagelists. I'm not
sure why 8 was selected in the first place, but I guess it made sense
that you don't want to reserve 15%+ of your memory for the pagelists.
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