From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261941AbUKCWbx (ORCPT ); Wed, 3 Nov 2004 17:31:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261963AbUKCW3M (ORCPT ); Wed, 3 Nov 2004 17:29:12 -0500 Received: from prgy-npn1.prodigy.com ([207.115.54.37]:43393 "EHLO oddball.prodigy.com") by vger.kernel.org with ESMTP id S261941AbUKCW0Z (ORCPT ); Wed, 3 Nov 2004 17:26:25 -0500 Message-ID: <41895A91.8090502@tmr.com> Date: Wed, 03 Nov 2004 17:24:17 -0500 From: Bill Davidsen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20040913 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Nick Piggin CC: Con Kolivas , linux , Andrew Morton , Ingo Molnar Subject: Re: [PATCH] remove interactive credit References: <418707CD.1080903@kolivas.org><418707CD.1080903@kolivas.org> <41877DF5.8070008@yahoo.com.au> In-Reply-To: <41877DF5.8070008@yahoo.com.au> 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 Nick Piggin wrote: > Con Kolivas wrote: > >> remove interactive credit >> >> >> >> ------------------------------------------------------------------------ >> >> Special casing tasks by interactive credit was helpful for preventing >> fully >> cpu bound tasks from easily rising to interactive status. >> However it did not select out tasks that had periods of being fully >> cpu bound >> and then sleeping while waiting on pipes, signals etc. This led to a more >> disproportionate share of cpu time. >> >> Backing this out will no longer special case only fully cpu bound >> tasks, and >> prevents the variable behaviour that occurs at startup before tasks >> declare >> themseleves interactive or not, and speeds up application startup >> slightly >> under certain circumstances. It does cost in interactivity slightly as >> load >> rises but it is worth it for the fairness gains. >> >> Signed-off-by: Con Kolivas >> > > I'm scared :( > > I'm in favour of any attempts to simplify things... but will it be two > months or three before this spontaneously explodes for half our userbase? > > Andrew's boss so he gets to decide >:) If I read the intent right, this is an example of worst case avoidance, where a little average interactivity is traded for preventing the case where a single misguided process gets most/all of the CPU and performance falls off the edge of the table. As a user I see that as the same line of thought which gave us low-latency patches, to trade a miniscule bit of one thing to avoid something really undesirable. I suspect there will be people who don't want to make this trade, although it sounds like a good one to me. -- -bill davidsen (davidsen@tmr.com) "The secret to procrastination is to put things off until the last possible moment - but no longer" -me