Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751165AbWBJHCX (ORCPT ); Fri, 10 Feb 2006 02:02:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751168AbWBJHCW (ORCPT ); Fri, 10 Feb 2006 02:02:22 -0500 Received: from fmr21.intel.com ([143.183.121.13]:47295 "EHLO scsfmr001.sc.intel.com") by vger.kernel.org with ESMTP id S1751165AbWBJHCW (ORCPT ); Fri, 10 Feb 2006 02:02:22 -0500 Date: Thu, 9 Feb 2006 23:01:45 -0800 From: "Siddha, Suresh B" To: Andrew Morton Cc: Con Kolivas , npiggin@suse.de, mingo@elte.hu, rostedt@goodmis.org, pwil3058@bigpond.net.au, suresh.b.siddha@intel.com, linux-kernel@vger.kernel.org, torvalds@osdl.org Subject: Re: [rfc][patch] sched: remove smpnice Message-ID: <20060209230145.A17405@unix-os.sc.intel.com> References: <20060207142828.GA20930@wotan.suse.de> <200602080157.07823.kernel@kolivas.org> <20060207141525.19d2b1be.akpm@osdl.org> <200602081011.09749.kernel@kolivas.org> <20060207153617.6520f126.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20060207153617.6520f126.akpm@osdl.org>; from akpm@osdl.org on Tue, Feb 07, 2006 at 03:36:17PM -0800 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1436 Lines: 32 On Tue, Feb 07, 2006 at 03:36:17PM -0800, Andrew Morton wrote: > Suresh, Martin, Ingo, Nick and Con: please drop everything, triple-check > and test this: > > From: Peter Williams > > This is a modified version of Con Kolivas's patch to add "nice" support to > load balancing across physical CPUs on SMP systems. I have couple of issues with this patch. a) on a lightly loaded system, this will result in higher priority job hopping around from one processor to another processor.. This is because of the code in find_busiest_group() which assumes that SCHED_LOAD_SCALE represents a unit process load and with nice_to_bias calculations this is no longer true(in the presence of non nice-0 tasks) My testing showed that 178.galgel in SPECfp2000 is down by ~10% when run with nice -20 on a 4P(8-way with HT) system compared to a nice-0 run. b) On a lightly loaded system, this can result in HT scheduler optimizations being disabled in presence of low priority tasks... in this case, they(low priority ones) can end up running on the same package, even in the presence of other idle packages.. Though this is not as serious as "a" above... thanks, suresh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/