Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753694AbYKQQy4 (ORCPT ); Mon, 17 Nov 2008 11:54:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751985AbYKQQys (ORCPT ); Mon, 17 Nov 2008 11:54:48 -0500 Received: from mx2.redhat.com ([66.187.237.31]:39955 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751910AbYKQQys (ORCPT ); Mon, 17 Nov 2008 11:54:48 -0500 Message-ID: <4921A1AF.1070909@redhat.com> Date: Mon, 17 Nov 2008 11:54:07 -0500 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 2.0.0.17 (X11/20080915) MIME-Version: 1.0 To: Linus Torvalds CC: KAMEZAWA Hiroyuki , KOSAKI Motohiro , Andrew Morton , LKML , linux-mm , Gene Heskett Subject: Re: [PATCH] mm: evict streaming IO cache first References: <20081115181748.3410.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20081115210039.537f59f5.akpm@linux-foundation.org> <49208E9A.5080801@redhat.com> <20081116204720.1b8cbe18.akpm@linux-foundation.org> <20081117153012.51ece88f.kamezawa.hiroyu@jp.fujitsu.com> <2f11576a0811162239w58555c6dq8a61ec184b22bd52@mail.gmail.com> <20081117155417.5cc63907.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1620 Lines: 39 Linus Torvalds wrote: > Another thing strikes me: it looks like the logic in "get_scan_ratio()" > has a tendency to get unbalanced - if we end up deciding that we should > scan a lot of anonymous pages, the scan numbers for anonymous pages will > go up, and we get even _more_ eager to scan those. Of course, "rotate" > events will then make us less likely again, but for streaming loads, you > wouldn't expect to see those at all. True for streaming loads - if we scan the file list and find mostly pages from streaming loads, we will become more eager to scan the file list. I do not expect streaming loads to ever hit the anon list in the same way, because anonymous pages start out referenced and on the active list, which means an anonymous deactivation will always be counted as a rotate event. > There seems to be another bug there wrt the "aging" - we age anon page > events and file page events independently, which sounds like it would make > the math totally nonsensical. We do that whole > > anon / (anon + file) That's an outdated comment. Andrew had a patch to update that comment, but it must have gotten lost somewhere. I'll send you a patch to update it. If you look at the actual calculation, you'l see that the scan percentages are keyed off just swappiness and the rotated/scanned ratios for each page category. -- All rights reversed. -- 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/