From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264192AbUGIEt6 (ORCPT ); Fri, 9 Jul 2004 00:49:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264228AbUGIEt6 (ORCPT ); Fri, 9 Jul 2004 00:49:58 -0400 Received: from fw.osdl.org ([65.172.181.6]:9126 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S264192AbUGIEtz (ORCPT ); Fri, 9 Jul 2004 00:49:55 -0400 Date: Thu, 8 Jul 2004 21:48:32 -0700 From: Andrew Morton To: Con Kolivas Cc: nickpiggin@yahoo.com.au, pwil3058@bigpond.net.au, Alexander.Povolotsky@marconi.com, linux-kernel@vger.kernel.org, efault@gmx.de, rml@tech9.net, mingo@elte.hu, elladan@eskimo.com, cks@utcc.utoronto.ca Subject: Re: Maximum frequency of re-scheduling (minimum time quantum ) que stio n Message-Id: <20040708214832.7d6b447c.akpm@osdl.org> In-Reply-To: References: <313680C9A886D511A06000204840E1CF08F42FE6@whq-msgusr-02.pit.comms.marconi.com> <40EDD980.4040608@bigpond.net.au> <40EDF8F5.2060808@yahoo.com.au> <20040708185726.1c375176.akpm@osdl.org> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Con Kolivas wrote: > > Andrew Morton writes: > > > Nick Piggin wrote: > >> > >> However well tested your scheduler might be, it needs several > >> orders of magnitude more testing ;) Maybe the best we can hope > >> for is compile time selectable alternatives. > > > > At this stage in the kernel lifecycle, for something as fiddly as the CPU > > scheduler we really should be 100% driven by problem reporting. > > > > If someone can identify a particular misbehaviour in the CPU scheduler then > > they should put their editor away and work to produce a solid testcase. > > Armed with that, we can then identify the source of the particular problem. > > > > It is at this point, and no earlier, that we can decide what an appropriate > > solution is. We then balance the risk of that solution against the severity > > of the problem which it solves and make a decision as to whether to proceed. > > > > Right now, the ratio of quality bug reporting to scheduler patching is > > bizarrely small. > > Is "for fun" not reason enough? Sure. "For 2.7" is a good reason, too. > I'm still keeping an eye out for firm "behavioural" bug reports on 2.6 and > would discuss or address them. OK, thanks. > Seriously the only reason I went down the rewrite path was to address > complaints about the complexity of the current design. It was also an > opportunity to start implementing some requested features. I certainly have > never suggested it should even be considered for 2.6. Yeah, I tend to think that the CPU scheduler is currently 90% good enough, and does seem to have become rather opaque. I wouldn't mind having a new "for fun" scheduler in -mm, except there's ongoing futzing with the current one to be sorted out.