From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751752AbXCUMDe (ORCPT ); Wed, 21 Mar 2007 08:03:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752614AbXCUMDe (ORCPT ); Wed, 21 Mar 2007 08:03:34 -0400 Received: from mx1.redhat.com ([66.187.233.31]:57123 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751752AbXCUMDd (ORCPT ); Wed, 21 Mar 2007 08:03:33 -0400 Message-ID: <46011EF6.3040704@redhat.com> Date: Wed, 21 Mar 2007 08:03:02 -0400 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 1.5.0.7 (X11/20061008) MIME-Version: 1.0 To: Nikita Danilov CC: Linux Kernel Mailing List , linux-mm Subject: Re: [RFC][PATCH] split file and anonymous page queues #3 References: <46005B4A.6050307@redhat.com> <17920.61568.770999.626623@gargle.gargle.HOWL> <460115D9.7030806@redhat.com> <17921.7074.900919.784218@gargle.gargle.HOWL> <46011E8F.2000109@redhat.com> In-Reply-To: <46011E8F.2000109@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Rik van Riel wrote: > Nikita Danilov wrote: > >> Probably I am missing something, but I don't see how that can help. For >> example, suppose (for simplicity) that we have swappiness of 100%, and >> that fraction of referenced anon pages gets slightly less than of file >> pages. get_scan_ratio() increases anon_percent, and shrink_zone() starts >> scanning anon queue more aggressively. As a result, pages spend less >> time there, and have less chance of ever being accessed, reducing >> fraction of referenced anon pages further, and triggering further >> increase in the amount of scanning, etc. Doesn't this introduce positive >> feed-back loop? > > It's a possibility, but I don't think it will be much of an > issue in practice. > > If it is, we can always use refaults as a correcting > mechanism - which would have the added benefit of being > able to do streaming IO without putting any pressure on > the active list, essentially clock-pro replacement with > just some tweaks to shrink_list()... As an aside, due to the use-once algorithm file pages are at a natural disadvantage already. I believe it would be really hard to construct a workload where anon pages suffer the positive feedback loop you describe... -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic. From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <46011EF6.3040704@redhat.com> Date: Wed, 21 Mar 2007 08:03:02 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [RFC][PATCH] split file and anonymous page queues #3 References: <46005B4A.6050307@redhat.com> <17920.61568.770999.626623@gargle.gargle.HOWL> <460115D9.7030806@redhat.com> <17921.7074.900919.784218@gargle.gargle.HOWL> <46011E8F.2000109@redhat.com> In-Reply-To: <46011E8F.2000109@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Nikita Danilov Cc: Linux Kernel Mailing List , linux-mm List-ID: Rik van Riel wrote: > Nikita Danilov wrote: > >> Probably I am missing something, but I don't see how that can help. For >> example, suppose (for simplicity) that we have swappiness of 100%, and >> that fraction of referenced anon pages gets slightly less than of file >> pages. get_scan_ratio() increases anon_percent, and shrink_zone() starts >> scanning anon queue more aggressively. As a result, pages spend less >> time there, and have less chance of ever being accessed, reducing >> fraction of referenced anon pages further, and triggering further >> increase in the amount of scanning, etc. Doesn't this introduce positive >> feed-back loop? > > It's a possibility, but I don't think it will be much of an > issue in practice. > > If it is, we can always use refaults as a correcting > mechanism - which would have the added benefit of being > able to do streaming IO without putting any pressure on > the active list, essentially clock-pro replacement with > just some tweaks to shrink_list()... As an aside, due to the use-once algorithm file pages are at a natural disadvantage already. I believe it would be really hard to construct a workload where anon pages suffer the positive feedback loop you describe... -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic. -- 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