From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751357AbWBQCy1 (ORCPT ); Thu, 16 Feb 2006 21:54:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751359AbWBQCy1 (ORCPT ); Thu, 16 Feb 2006 21:54:27 -0500 Received: from fmr22.intel.com ([143.183.121.14]:49625 "EHLO scsfmr002.sc.intel.com") by vger.kernel.org with ESMTP id S1751357AbWBQCy0 (ORCPT ); Thu, 16 Feb 2006 21:54:26 -0500 Date: Thu, 16 Feb 2006 18:54:03 -0800 From: "Siddha, Suresh B" To: Peter Williams Cc: "Siddha, Suresh B" , Andrew Morton , Linux Kernel Mailing List , npiggin@suse.de, Ingo Molnar , Steven Rostedt , Linus Torvalds , Con Kolivas Subject: Re: [PATCH] Fix smpnice high priority task hopping problem Message-ID: <20060216185403.B27025@unix-os.sc.intel.com> References: <43F3C9C6.5080606@bigpond.net.au> <20060216171357.A27025@unix-os.sc.intel.com> <43F53553.50904@bigpond.net.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <43F53553.50904@bigpond.net.au>; from pwil3058@bigpond.net.au on Fri, Feb 17, 2006 at 01:30:43PM +1100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 17, 2006 at 01:30:43PM +1100, Peter Williams wrote: > On a normal system, would either of them be moved anyway? Possible. Because when the migration thread runs it moves the current running task out of the processor and the checks in can_migrate_task() like "sd->nr_balance_failed > sd->cache_nice_tries" can result in cache hot task move to the idle package.. This is a round about way and we should not depend on this behavior.. > > > > > To fix my reported problem, we need to make sure that find_busiest_group() > > doesn't find an imbalance.. > > I disagree. If this causes a problem with your "optimizations" then I > think that you need to fix the "optimizations". > > There's a rational argument (IMHO) that this patch should be applied > even in the absence of the smpnice patches as it prevents > active_load_balance() doing unnecessary work. If this isn't good for > hypo threading then hypo threading is a special case and needs to handle > it as such. active load balance is designed only with HT optimizations in mind. And now multi-core optimizations also use this active load balance. No one else uses active load balance. thanks, suresh