From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262146AbVAUGwo (ORCPT ); Fri, 21 Jan 2005 01:52:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262093AbVAUGwo (ORCPT ); Fri, 21 Jan 2005 01:52:44 -0500 Received: from ppp-217-133-42-200.cust-adsl.tiscali.it ([217.133.42.200]:39513 "EHLO dualathlon.random") by vger.kernel.org with ESMTP id S262146AbVAUGwg (ORCPT ); Fri, 21 Jan 2005 01:52:36 -0500 Date: Fri, 21 Jan 2005 07:52:35 +0100 From: Andrea Arcangeli To: Nick Piggin Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: OOM fixes 2/5 Message-ID: <20050121065235.GD17050@dualathlon.random> References: <20050121054840.GA12647@dualathlon.random> <20050121054916.GB12647@dualathlon.random> <20050120222056.61b8b1c3.akpm@osdl.org> <1106289375.5171.7.camel@npiggin-nld.site> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1106289375.5171.7.camel@npiggin-nld.site> X-AA-GPG-Key: 1024D/68B9CB43 13D9 8355 295F 4823 7C49 C012 DFA1 686E 68B9 CB43 X-AA-PGP-Key: 1024R/CB4660B9 CC A0 71 81 F4 A0 63 AC C0 4B 81 1D 8C 15 C8 E5 X-Cpushare-GPG-Key: 1024D/4D11C21C 5F99 3C8B 5142 EB62 26C3 2325 8989 B72A 4D11 C21C X-Cpushare-SSL-SHA1-Cert: 3812 CD76 E482 94AF 020C 0FFA E1FF 559D 9B4F A59B X-Cpushare-SSL-MD5-Cert: EDA5 F2DA 1D32 7560 5E07 6C91 BFFC B885 User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 21, 2005 at 05:36:14PM +1100, Nick Piggin wrote: > I think it should be turned on by default. I can't recall what I think it too, since the number of people that can be bitten by this is certainly higher than the number of people who knows the VM internals and for what kind of workloads they need to enable this by hand to avoid risking lockups (notably with boxes without swap or with heavy pagetable allocations all the time which is not uncommon with db usage). This is needed on x86-64 too to avoid pagetables to lockup the dma zone. Or anyways it's needed also on x86 for the dma zone on <1G boxes too. Anyway if you leave it off by default I don't mind, with my new code forward ported stright from 2.4 mainline, it's possible for the first time to set it from userspace without having to embed knowledge on the kernel min_kbytes settings at boot time. So if you want it down by default it simply means we'll guarantee it on our distro with userland. Setting a sysctl at boot time is no big deal for us (of course leaving it enabled by default in kernel space is older distro where userland isn't yet aware about it). So it's pretty much up to you, as long as we can easily fixup in userland is fine with me and I already tried a dozen times to push mainline in what I believe to be the right direction (like I already did in 2.4 mainline since that same code is enabled by default in 2.4). The sysctl name had to change to lowmem_reserve_ratio because its semantics are completely different now.