Re: [PATCH -mmotm-2009-12-10-17-19] Prevent churning of zero pagein LRU list.

[Rik van Riel]

On 12/27/2009 09:53 PM, Minchan Kim wrote:
> VM doesn't add zero page to LRU list.
> It means zero page's churning in LRU list is pointless.
>
> As a matter of fact, zero page can't be promoted by mark_page_accessed
> since it doesn't have PG_lru.
>
> This patch prevent unecessary mark_page_accessed call of zero page
> alghouth caller want FOLL_TOUCH.
>
> Signed-off-by: Minchan Kim<minchan.kim@xxxxxxxxx>

The code looks correct, but I wonder how frequently we run into
the zero page in this code, vs. how much the added cost is of
having this extra code in follow_page.

What kind of problem were you running into that motivated you
to write this patch?

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