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

[Cong Wang]

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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