On Fri, Jan 13, 2012 at 05:40:19PM +0900, KAMEZAWA Hiroyuki wrote: > > From 1008e84d94245b1e7c4d237802ff68ff00757736 Mon Sep 17 00:00:00 2001 > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> > Date: Thu, 12 Jan 2012 15:53:24 +0900 > Subject: [PATCH 3/7] memcg: remove PCG_MOVE_LOCK flag from pc->flags. > > PCG_MOVE_LOCK bit is used for bit spinlock for avoiding race between > memcg's account moving and page state statistics updates. > > Considering page-statistics update, very hot path, this lock is > taken only when someone is moving account (or PageTransHuge()) > And, now, all moving-account between memcgroups (by task-move) > are serialized. > > So, it seems too costly to have 1bit per page for this purpose. > > This patch removes PCG_MOVE_LOCK and add hashed rwlock array > instead of it. This works well enough. Even when we need to > take the lock, we don't need to disable IRQ in hot path because > of using rwlock. > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> ... > +#define NR_MOVE_ACCOUNT_LOCKS (NR_CPUS) > +#define move_account_hash(page) ((page_to_pfn(page) % NR_MOVE_ACCOUNT_LOCKS)) You still tend to add too many parentheses into macros ;) -- Kirill A. Shutemov -- 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>