From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754400AbYJXJ64 (ORCPT ); Fri, 24 Oct 2008 05:58:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752327AbYJXJ6n (ORCPT ); Fri, 24 Oct 2008 05:58:43 -0400 Received: from casper.infradead.org ([85.118.1.10]:36221 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751833AbYJXJ6m (ORCPT ); Fri, 24 Oct 2008 05:58:42 -0400 Message-Id: <20081024091109.422586607@chello.nl> References: <20081024090611.936552213@chello.nl> User-Agent: quilt/0.46-1 Date: Fri, 24 Oct 2008 11:06:12 +0200 From: Peter Zijlstra To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, efault@gmx.de, vatsa@in.ibm.com, Peter Zijlstra Subject: [PATCH 1/8] sched: fix a find_busiest_group buglet Content-Disposition: inline; filename=sched-fbg-buglet.patch X-Bad-Reply: References but no 'Re:' in Subject. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In one of the group load balancer patches: commit 408ed066b11cf9ee4536573b4269ee3613bd735e Author: Peter Zijlstra Date: Fri Jun 27 13:41:28 2008 +0200 Subject: sched: hierarchical load vs find_busiest_group The following change: - if (max_load - this_load + SCHED_LOAD_SCALE_FUZZ >= + if (max_load - this_load + 2*busiest_load_per_task >= busiest_load_per_task * imbn) { made the condition always true, because imbn is [1,2]. Therefore, remove the 2*, and give the it a fair chance. Signed-off-by: Peter Zijlstra --- kernel/sched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6/kernel/sched.c =================================================================== --- linux-2.6.orig/kernel/sched.c +++ linux-2.6/kernel/sched.c @@ -3343,7 +3343,7 @@ small_imbalance: } else this_load_per_task = cpu_avg_load_per_task(this_cpu); - if (max_load - this_load + 2*busiest_load_per_task >= + if (max_load - this_load + busiest_load_per_task >= busiest_load_per_task * imbn) { *imbalance = busiest_load_per_task; return busiest; --