From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 4753D6B0047 for ; Thu, 8 Jan 2009 11:49:00 -0500 (EST) Date: Thu, 8 Jan 2009 08:48:23 -0800 (PST) From: Linus Torvalds Subject: Re: Increase dirty_ratio and dirty_background_ratio? In-Reply-To: <20090108.082413.156881254.davem@davemloft.net> Message-ID: References: <20090107.125133.214628094.davem@davemloft.net> <20090108030245.e7c8ceaf.akpm@linux-foundation.org> <20090108.082413.156881254.davem@davemloft.net> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: David Miller Cc: akpm@linux-foundation.org, peterz@infradead.org, jack@suse.cz, linux-kernel@vger.kernel.org, linux-mm@kvack.org, npiggin@suse.de List-ID: On Thu, 8 Jan 2009, David Miller wrote: > From: Andrew Morton > Date: Thu, 8 Jan 2009 03:02:45 -0800 > > > The kernel can't get this right - it doesn't know the usage > > patterns/workloads, etc. > > I don't agree with that. We can certainly try to tune it better. And I do agree that we did a very drastic reduction in the dirty limits, and we can probably look at raising it up a bit. I definitely do not want to go back to the old 40% dirty model, but I could imagine 10/20% for async/sync (it's 5/10 now, isn't it?) But I do not want to be guided by benchmarks per se, unless they are latency-sensitive. And one of the reasons for the drastic reduction was that there was actually a real deadlock situation with the old limits, although we solved that one twice - first by reducing the limits drastically, and then by making them be relative to the non-highmem memory (rather than all of it). So in effect, we actually reduced the limits more than originally intended, although that particular effect should be noticeable mainly just on 32-bit x86. I'm certainly open to tuning. As long as "tuning" doesn't involve something insane like dbench numbers. Linus -- 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