On Wed, Mar 02, 2011 at 12:35:58AM +0900, Minchan Kim wrote: > On Tue, Mar 01, 2011 at 01:49:25PM +0900, KAMEZAWA Hiroyuki wrote: > > On Tue, 1 Mar 2011 13:11:46 +0900 > > Minchan Kim <minchan.kim@xxxxxxxxx> wrote: > > > > > On Tue, Mar 01, 2011 at 08:42:09AM +0900, KAMEZAWA Hiroyuki wrote: > > > > On Mon, 28 Feb 2011 10:18:27 +0000 > > > > Mel Gorman <mel@xxxxxxxxx> wrote: > > > > > > > > > > BTW, can't we drop disable_irq() from all lru_lock related codes ? > > > > > > > > > > > > > > > > I don't think so - at least not right now. Some LRU operations such as LRU > > > > > pagevec draining are run from IPI which is running from an interrupt so > > > > > minimally spin_lock_irq is necessary. > > > > > > > > > > > > > pagevec draining is done by workqueue(schedule_on_each_cpu()). > > > > I think only racy case is just lru rotation after writeback. > > > > > > put_page still need irq disable. > > > > > > > Aha..ok. put_page() removes a page from LRU via __page_cache_release(). > > Then, we may need to remove a page from LRU under irq context. > > Hmm... > > But as __page_cache_release's comment said, normally vm doesn't release page in > irq context. so it would be rare. > If we can remove it, could we change all of spin_lock_irqsave with spin_lock? > If it is right, I think it's very desirable to reduce irq latency. > > How about this? It's totally a quick implementation and untested. > I just want to hear opinions of you guys if the work is valuable or not before > going ahead. pages freed from irq shouldn't be PageLRU. deferring freeing to workqueue doesn't look ok. firewall loads runs only from irq and this will cause some more work and a delay in the freeing. I doubt it's worhwhile especially for the lru_lock. -- 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>