From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 7 Oct 2002 21:35:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 7 Oct 2002 21:35:36 -0400 Received: from c16688.thoms1.vic.optusnet.com.au ([210.49.244.54]:40640 "EHLO kolivas.net") by vger.kernel.org with ESMTP id ; Mon, 7 Oct 2002 21:35:34 -0400 Message-ID: <1034041272.3da237b8b7908@kolivas.net> Date: Tue, 8 Oct 2002 11:41:12 +1000 From: Con Kolivas To: Andrew Morton Cc: linux kernel mailing list Subject: Re: [BENCHMARK] 2.5.40-mm2 with contest References: <1033960902.3da0fdc6839aa@kolivas.net> <3DA139EC.8A34A593@digeo.com> <1034038912.3da22e805c7c0@kolivas.net> <3DA233EC.1119CD7B@digeo.com> In-Reply-To: <3DA233EC.1119CD7B@digeo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT User-Agent: Internet Messaging Program (IMP) 3.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Quoting Andrew Morton : > Con Kolivas wrote: > > > > ... > > - swap_tendency = mapped_ratio / 2 + distress + vm_swappiness; > > + swap_tendency = mapped_ratio / 2 + distress ; > > + if (swap_tendency > 50){ > > + if (vm_swappiness <= 990) vm_swappiness+=10; > > + } > > + else > > + if (vm_swappiness > 0) vm_swappiness--; > > + swap_tendency += (vm_swappiness / 10); > > > > heh, that could work. So basically you're saying "the longer we're > under swap stress, the more swappy we want to get". Exactly, which made complete sense to me. > > Problem is, users have said they don't want that. They say that they > want to copy ISO images about all day and not swap. I think. But do they really want that or do they think they want that without knowing the consequences of such a setting? > It worries me. It means that we'll be really slow to react to sudden > load swings, and it increases the complexity of the analysis and > testing. And I really do want to give the user a single knob, > which has understandable semantics and for which I can feasibly test > all operating regions. > > I really, really, really, really don't want to get too fancy in there. Well I made it as simple as I possibly could. It seems to do what they want (not swappy) but not at the expense of making the machine never swapping when it really needs to - and the performance seems to be better all round in real usage. I guess the only thing is it isn't a fixed number... unless we set a maximum swappiness level or... but then it starts getting unnecessarily complicated with questionable benefits. > I have changed this code a bit, and have added other things. Mainly > over on the writer throttling side, which tends to be the place where > the stress comes from in the first place. /me waits but is a little disappointed Con