On Fri, 2011-10-28 at 07:19 +0800, Minchan Kim wrote: > 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@xxxxxxxxx> > > In case of a, it doesn't matter ordering of subpages. > As a huge page, age of sub pages are same. It does matter. Hugepage is split first and then reclaim. if page, page +HPAGE_PMD_NR-1 is reclaimed, you can't get an order-1 page. but if page, page+1 is reclaimed, you can. > In case of b, what a page is located in tail and other subpages are located in head > isn't critical problem. Same way here. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>