On Wed, Sep 29, 2010 at 10:57:40AM +0800, Shaohua Li wrote: > With commit 645747462435, pte referenced file page isn't activated in inactive > list scan. For VM_EXEC page, if it can't get a chance to active list, the > executable page protect loses its effect. We protect such page in inactive scan > here, now such page will be guaranteed cached in a full scan of active and > inactive list, which restores previous behavior. This change was in the back of my head since the used-once detection was merged but there were never any regressions reported that would indicate a requirement for it. Does this patch fix a problem you observed? > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -608,8 +608,15 @@ static enum page_references page_check_references(struct page *page, > * quickly recovered. > */ > SetPageReferenced(page); > - > - if (referenced_page) > + /* > + * Identify pte referenced and file-backed pages and give them > + * one trip around the active list. So that executable code get > + * better chances to stay in memory under moderate memory > + * pressure. JVM can create lots of anon VM_EXEC pages, so we > + * ignore them here. PTE-referenced PageAnon() pages are activated unconditionally a few lines further up, so the page_is_file_cache() check filters only shmem pages. I doubt this was your intention...? > + */ > + if (referenced_page || ((vm_flags & VM_EXEC) && > + page_is_file_cache(page))) > return PAGEREF_ACTIVATE; > > return PAGEREF_KEEP; -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>