lkml.org 
[lkml]   [2011]   [Oct]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch 4/5]thp: correct order in lru list for split huge page
On Tue, Oct 25, 2011 at 10:59:37AM +0800, Shaohua Li wrote:
> If a huge page is split, all the subpages should live in lru list adjacently
> because they should be taken as a whole.
> In page split, with current code:
> a. if huge page is in lru list, the order is: page, page+HPAGE_PMD_NR-1,
> page + HPAGE_PMD_NR-2, ..., page + 1(in lru page reclaim order)
> b. otherwise, the order is: page, ..other pages.., page + 1, page + 2, ...(in
> lru page reclaim order). page + 1 ... page + HPAGE_PMD_NR - 1 are in the lru
> reclaim tail.
>
> In case a, the order is wrong. In case b, page is isolated (to be reclaimed),
> but other tail pages will not soon.
>
> With below patch:
> in case a, the order is: page, page + 1, ... page + HPAGE_PMD_NR-1(in lru page
> reclaim order).
> in case b, the order is: page + 1, ... page + HPAGE_PMD_NR-1 (in lru page reclaim
> order). The tail pages are in the lru reclaim head.
>
> Signed-off-by: Shaohua Li <shaohua.li@intel.com>

In case of a, it doesn't matter ordering of subpages.
As a huge page, age of sub pages are same.

In case of b, what a page is located in tail and other subpages are located in head
isn't critical problem.

Having said that, it's more consistent and simple patch.
So I like that. Nice catch, Shaohua!

Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
--
Kind regards,
Minchan Kim


\
 
 \ /
  Last update: 2011-10-28 01:23    [W:0.099 / U:0.356 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site