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