From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265534AbUEZMQC (ORCPT ); Wed, 26 May 2004 08:16:02 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265529AbUEZMQC (ORCPT ); Wed, 26 May 2004 08:16:02 -0400 Received: from smtp016.mail.yahoo.com ([216.136.174.113]:39809 "HELO smtp016.mail.yahoo.com") by vger.kernel.org with SMTP id S265534AbUEZMOm (ORCPT ); Wed, 26 May 2004 08:14:42 -0400 Message-ID: <40B48A2E.4030909@yahoo.com.au> Date: Wed, 26 May 2004 22:14:38 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040401 Debian/1.6-4 X-Accept-Language: en MIME-Version: 1.0 To: Buddy Lumpkin CC: "'William Lee Irwin III'" , orders@nodivisions.com, linux-kernel@vger.kernel.org Subject: Re: why swap at all? References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Buddy Lumpkin wrote: > > > -----Original Message----- > From: William Lee Irwin III [mailto:wli@holomorphy.com] > Sent: Wednesday, May 26, 2004 2:09 AM > To: Buddy Lumpkin > Cc: orders@nodivisions.com; linux-kernel@vger.kernel.org > Subject: Re: why swap at all? > > On Wed, May 26, 2004 at 01:30:09AM -0700, Buddy Lumpkin wrote: > >>As for your short, two sentence comment below, let me save you the energy > > of > >>insinuations and translate your message the way I read it: >>------------------------------------------------------------------------- >>I don't recognize your name, therefore you can't possibly have a valuable >>opinion on the direction VM system development should go. I doubt you have >>an actual performance problem to share, but if you do, please share it and >>go away so that we can work on solving the problem. >>-------------------------------------------------------------------------- >>My response: >>Get over yourself. > > >>What the Hell? I have enough bugs I'm paid to fix that I'm not going to >>tolerate harassment for requesting that claims that the kernel behaves >>pathologically in some scenario be cast as comprehensible bugreports. >>It's also worth noting that paying customers don't respond so uncouthly. > > > >>-- wli > > > If you follow the thread, you will see no claim from me that there is > anything wrong with the kernel. I simply stated that the priority of VM > system development should focus on physical memory, and that physical memory > access should not suffer as a result of some tradeoff that improves the > performance of the VM system when free physical memory is low and there is > heavy use of the swap device. > You also went on to say: > This of course doesn't address the VM paging storms that happen due to large > amounts of file system writes. Once the pagecache fills up, dirty pages must > be evicted from the pagecache so that new pages can be added to the > pagecache. By and large, Linux doesn't reclaim dirty pages from the pagecache, and it should not have paging storms due to large amounts of file system writes. If you had a workload where it does, we would be interested to see it. I pointed out to you that this is what Bill was asking you to file a detailed report about. > I can't speak whether or not a case like this currently exists, but I know > optimizing swap performance is a very complicated yet captivating subject > that has consumed many a posts on this list. People have tried to optimize > every part of the VM before, so I was just calling out what I believe to be > a very reasonable and practical goal and put a little bit of substance > around why I think it's practical. > Actually, during the 2.5 development cycle, swapping performance got fairly neglected to the point where we were performing twice as bad as 2.4 for most things. I (and others) recently improved this because real people doing real things were complaining. [snip rant] > > I can picture where this is going. Here is an interview between you and a > popular Linux magazine in two years: > > > Linux Magazine: You have contributed to linux for quite some time, correct? > > William: Oh yes, it is my hobby and occupation. I love my work. > > Linux Magazine: You have done all these wonderful things! > > William: Thanks, I am very proud of that > > Linux Magazine: Why did you make such and such decision that backfired? > > William: I don't have to answer that, I don't owe you anything and your not > a paying customer. > > Give me a break. > What?? Give *you* a break? From a fictional interview you concocted? Give me a break.