Re: [PATCH] mm: raise MemFree by reverting percpu_pagelist_fractionto 0

From: Cong Wang
Date: Mon May 14 2012 - 04:51:23 EST

On 05/12/2012 12:35 AM, Sasha Levin wrote:
On Fri, May 11, 2012 at 6:27 PM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
On Fri, May 11, 2012 at 2:01 AM, Minchan Kim<minchan@xxxxxxxxxx> 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.

1/x is not user-friendly, other vm sysctl's use percentage (x%), for example, overcommit_ratio.
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