On Wed, 27 Apr 2011 01:25:23 +0900 Minchan Kim <minchan.kim@xxxxxxxxx> wrote: > This patch defines new APIs to putback the page into previous position of LRU. > The idea is simple. > > When we try to putback the page into lru list and if friends(prev, next) of the pages > still is nearest neighbor, we can insert isolated page into prev's next instead of > head of LRU list. So it keeps LRU history without losing the LRU information. > > Before : > LRU POV : H - P1 - P2 - P3 - P4 -T > > Isolate P3 : > LRU POV : H - P1 - P2 - P4 - T > > Putback P3 : > if (P2->next == P4) > putback(P3, P2); > So, > LRU POV : H - P1 - P2 - P3 - P4 -T > > For implement, we defines new structure pages_lru which remebers > both lru friend pages of isolated one and handling functions. > > But this approach has a problem on contiguous pages. > In this case, my idea can not work since friend pages are isolated, too. > It means prev_page->next == next_page always is false and both pages are not > LRU any more at that time. It's pointed out by Rik at LSF/MM summit. > So for solving the problem, I can change the idea. > I think we don't need both friend(prev, next) pages relation but > just consider either prev or next page that it is still same LRU. > Worset case in this approach, prev or next page is free and allocate new > so it's in head of LRU and our isolated page is located on next of head. > But it's almost same situation with current problem. So it doesn't make worse > than now and it would be rare. But in this version, I implement based on idea > discussed at LSF/MM. If my new idea makes sense, I will change it. > I think using only 'next'(prev?) pointer will be enough. Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx 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>