Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756117AbXKVCQk (ORCPT ); Wed, 21 Nov 2007 21:16:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753430AbXKVCQc (ORCPT ); Wed, 21 Nov 2007 21:16:32 -0500 Received: from paragon.brong.net ([74.52.187.94]:53388 "EHLO paragon.brong.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753269AbXKVCQb (ORCPT ); Wed, 21 Nov 2007 21:16:31 -0500 Date: Thu, 22 Nov 2007 13:16:28 +1100 From: Bron Gondwana To: Bron Gondwana Cc: Linus Torvalds , Christian Kujau , Andrew Morton , Peter Zijlstra , Linux Kernel Mailing List , robm@fastmail.fm Subject: Re: mmap dirty limits on 32 bit kernels (Was: [BUG] New Kernel Bugs) Message-ID: <20071122021628.GA8660@brong.net> References: <20071113130411.26ccae12.akpm@linux-foundation.org> <20071115040708.GB15302@brong.net> <20071115052538.GA21522@brong.net> <20071115115049.GA8297@brong.net> <20071121235115.GA30679@brong.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071121235115.GA30679@brong.net> Organization: brong.net User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2061 Lines: 47 On Thu, Nov 22, 2007 at 10:51:15AM +1100, Bron Gondwana wrote: > On Thu, Nov 15, 2007 at 08:32:22AM -0800, Linus Torvalds wrote: > > If this patch makes a difference, please holler. I think it's the correct > > thing to do, but I'm not going to actually commit it without somebody > > saying that it makes a difference (and preferably Peter Zijlstra and > > Andrew acking it too). > > mmap: mmap call failed: errno: 12 errmsg: Cannot allocate memory > > Yep, that's "fixed" the problem alright! No way this puppy is > dirtying 2Gb of memory any more. > > http://linux.brong.fastmail.fm/2007-11-22/bmtest.pl Alternatively perhaps I'm just a moron who used a config file with: CONFIG_PAGE_OFFSET=0x80000000 set to build the new kernel (I hadn't committed it because it turned out not to solve the issue it was there for). That would explain a few things. [root@lb1 perl]$ free total used free shared buffers cached Mem: 4150620 2272284 1878336 0 11212 2066536 -/+ buffers/cache: 194536 3956084 Swap: 2096472 0 2096472 That's more the usage I would expect to see. Now for the downside. It works again, but it still runs slow. Seems to hit (and this is totally unscientific, I'm just watching the numbers scroll by) at about 120000 writes rather than 70000 writes, but that's still not fitting the while file dirty. I notice that PF_LESS_THROTTLE gets set by nfsd to get an extra 25% bonus free space allocated. Potentially dcc could use similar tricks to claim extra space if that knob is available up in userspace. I'm happy to patch dcc as well if I have to, I'm already backporting it, so adding another little quilt directory and applying it is pretty trivial (must try guilt/stgit one of these days) Bron. - 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/