From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965886AbXCLOWA (ORCPT ); Mon, 12 Mar 2007 10:22:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965887AbXCLOWA (ORCPT ); Mon, 12 Mar 2007 10:22:00 -0400 Received: from [212.12.190.20] ([212.12.190.20]:32981 "EHLO raad.intranet" rhost-flags-FAIL-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S965886AbXCLOV7 (ORCPT ); Mon, 12 Mar 2007 10:21:59 -0400 From: Al Boldi To: Con Kolivas Subject: Re: [ANNOUNCE] RSDL completely fair starvation free interactive cpu scheduler Date: Mon, 12 Mar 2007 17:14:24 +0300 User-Agent: KMail/1.5 Cc: ck list , linux-kernel@vger.kernel.org References: <200703042335.26785.a1426z@gawab.com> <200703121426.00854.a1426z@gawab.com> <200703122352.51257.kernel@kolivas.org> In-Reply-To: <200703122352.51257.kernel@kolivas.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200703121714.25034.a1426z@gawab.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Con Kolivas wrote: > > > The higher priority one always get 6-7ms whereas the lower priority > > > one runs 6-7ms and then one larger perfectly bound expiration amount. > > > Basically exactly as I'd expect. The higher priority task gets > > > precisely RR_INTERVAL maximum latency whereas the lower priority task > > > gets RR_INTERVAL min and full expiration (according to the virtual > > > deadline) as a maximum. That's exactly how I intend it to work. Yes I > > > realise that the max latency ends up being longer intermittently on > > > the niced task but that's -in my opinion- perfectly fine as a > > > compromise to ensure the nice 0 one always gets low latency. > > > > I think, it should be possible to spread this max expiration latency > > across the rotation, should it not? > > There is a way that I toyed with of creating maps of slots to use for each > different priority, but it broke the O(1) nature of the virtual deadline > management. Minimising algorithmic complexity seemed more important to > maintain than getting slightly better latency spreads for niced tasks. It > also appeared to be less cache friendly in design. I could certainly try > and implement it but how much importance are we to place on latency of > niced tasks? Are you aware of any usage scenario where latency sensitive > tasks are ever significantly niced in the real world? It only takes one negatively nice'd proc to affect X adversely. Thanks! -- Al