From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id EDAD66B003D for ; Fri, 1 May 2009 18:36:53 -0400 (EDT) Date: Fri, 1 May 2009 15:32:55 -0700 From: Andrew Morton Subject: Re: [PATCH] vmscan: evict use-once pages first (v3) Message-Id: <20090501153255.0f412420.akpm@linux-foundation.org> In-Reply-To: <20090429131436.640f09ab@cuia.bos.redhat.com> References: <20090428044426.GA5035@eskimo.com> <20090428192907.556f3a34@bree.surriel.com> <1240987349.4512.18.camel@laptop> <20090429114708.66114c03@cuia.bos.redhat.com> <2f11576a0904290907g48e94e74ye97aae593f6ac519@mail.gmail.com> <20090429131436.640f09ab@cuia.bos.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Rik van Riel Cc: kosaki.motohiro@jp.fujitsu.com, peterz@infradead.org, elladan@eskimo.com, linux-kernel@vger.kernel.org, tytso@mit.edu, linux-mm@kvack.org List-ID: On Wed, 29 Apr 2009 13:14:36 -0400 Rik van Riel wrote: > When the file LRU lists are dominated by streaming IO pages, > evict those pages first, before considering evicting other > pages. > > This should be safe from deadlocks or performance problems > because only three things can happen to an inactive file page: > 1) referenced twice and promoted to the active list > 2) evicted by the pageout code > 3) under IO, after which it will get evicted or promoted > > The pages freed in this way can either be reused for streaming > IO, or allocated for something else. If the pages are used for > streaming IO, this pageout pattern continues. Otherwise, we will > fall back to the normal pageout pattern. > > .. > > +int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg) > +{ > + unsigned long active; > + unsigned long inactive; > + > + inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_FILE); > + active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_FILE); > + > + return (active > inactive); > +} This function could trivially be made significantly more efficient by changing it to do a single pass over all the zones of all the nodes, rather than two passes. > static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, > struct zone *zone, struct scan_control *sc, int priority) > { > int file = is_file_lru(lru); > > - if (lru == LRU_ACTIVE_FILE) { > + if (lru == LRU_ACTIVE_FILE && inactive_file_is_low(zone, sc)) { > shrink_active_list(nr_to_scan, zone, sc, priority, file); > return 0; > } And it does get called rather often. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org