Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757185AbZD2QKh (ORCPT ); Wed, 29 Apr 2009 12:10:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753015AbZD2QK1 (ORCPT ); Wed, 29 Apr 2009 12:10:27 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:40298 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752280AbZD2QK1 (ORCPT ); Wed, 29 Apr 2009 12:10:27 -0400 Subject: Re: [PATCH] vmscan: evict use-once pages first (v2) From: Peter Zijlstra To: Rik van Riel Cc: Elladan , linux-kernel@vger.kernel.org, tytso@mit.edu, kosaki.motohiro@jp.fujitsu.com, linux-mm@kvack.org In-Reply-To: <20090429114708.66114c03@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> Content-Type: text/plain Date: Wed, 29 Apr 2009 18:10:10 +0200 Message-Id: <1241021410.8021.556.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2472 Lines: 65 On Wed, 2009-04-29 at 11:47 -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. > > Signed-off-by: Rik van Riel > --- > On Wed, 29 Apr 2009 08:42:29 +0200 > Peter Zijlstra wrote: > > > Isn't there a hole where LRU_*_FILE << LRU_*_ANON and we now stop > > shrinking INACTIVE_ANON even though it makes sense to. > > Peter, after looking at this again, I believe that the get_scan_ratio > logic should take care of protecting the anonymous pages, so we can > get away with this following, less intrusive patch. > > Elladan, does this smaller patch still work as expected? Provided of course that it actually fixes Elladan's issue, this looks good to me. Acked-by: Peter Zijlstra > diff --git a/mm/vmscan.c b/mm/vmscan.c > index eac9577..4471dcb 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1489,6 +1489,18 @@ static void shrink_zone(int priority, struct zone *zone, > nr[l] = scan; > } > > + /* > + * When the system is doing streaming IO, memory pressure here > + * ensures that active file pages get deactivated, until more > + * than half of the file pages are on the inactive list. > + * > + * Once we get to that situation, protect the system's working > + * set from being evicted by disabling active file page aging. > + * The logic in get_scan_ratio protects anonymous pages. > + */ > + if (nr[LRU_INACTIVE_FILE] > nr[LRU_ACTIVE_FILE]) > + nr[LRU_ACTIVE_FILE] = 0; > + > while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || > nr[LRU_INACTIVE_FILE]) { > for_each_evictable_lru(l) { > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/