From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751542AbWDYChi (ORCPT ); Mon, 24 Apr 2006 22:37:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751543AbWDYChh (ORCPT ); Mon, 24 Apr 2006 22:37:37 -0400 Received: from omta03sl.mx.bigpond.com ([144.140.92.155]:51440 "EHLO omta03sl.mx.bigpond.com") by vger.kernel.org with ESMTP id S1750939AbWDYChh (ORCPT ); Mon, 24 Apr 2006 22:37:37 -0400 Message-ID: <444D8B6F.7050601@bigpond.net.au> Date: Tue, 25 Apr 2006 12:37:35 +1000 From: Peter Williams User-Agent: Thunderbird 1.5 (X11/20060313) MIME-Version: 1.0 To: Andrew Morton CC: kernel@kolivas.org, mingo@elte.hu, suresh.b.siddha@intel.com, efault@gmx.de, nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org, kenneth.w.chen@intel.com Subject: Re: [PATCH] sched: Fix boolean expression in move_tasks() References: <444D637F.5040702@bigpond.net.au> <20060424191358.08c73e31.akpm@osdl.org> In-Reply-To: <20060424191358.08c73e31.akpm@osdl.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Authentication-Info: Submitted using SMTP AUTH PLAIN at omta03sl.mx.bigpond.com from [147.10.133.38] using ID pwil3058@bigpond.net.au at Tue, 25 Apr 2006 02:37:35 +0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > Peter Williams wrote: >> Negate the expression and apply de Marcos rule to simplify it. This >> patch is on top of >> sched-avoid-unnecessarily-moving-highest-priority-task-move_tasks.patch >> >> Signed-off-by: Peter Williams >> >> -- >> Peter Williams pwil3058@bigpond.net.au >> >> "Learning, n. The kind of ignorance distinguishing the studious." >> -- Ambrose Bierce >> >> >> [smpnice-fix-boolean-expression text/plain (824 bytes)] >> Index: MM-2.6.17-rc1-mm3/kernel/sched.c >> =================================================================== >> --- MM-2.6.17-rc1-mm3.orig/kernel/sched.c 2006-04-21 12:26:54.000000000 +1000 >> +++ MM-2.6.17-rc1-mm3/kernel/sched.c 2006-04-25 09:09:54.000000000 +1000 >> @@ -2108,7 +2108,7 @@ skip_queue: >> */ >> skip_for_load = tmp->load_weight > rem_load_move; >> if (skip_for_load && idx < this_best_prio) >> - skip_for_load = busiest_best_prio_seen || idx != busiest_best_prio; >> + skip_for_load = !busiest_best_prio_seen && idx == busiest_best_prio; > > But Suresh's > sched-avoid-unnecessarily-moving-highest-priority-task-move_tasks-fix.patch > changed all this code: > > /* > * To help distribute high priority tasks accross CPUs we don't > * skip a task if it will be the highest priority task (i.e. smallest > * prio value) on its new queue regardless of its load weight > */ > skip_for_load = tmp->load_weight > rem_load_move; > if (skip_for_load && idx < this_best_prio && idx == busiest_best_prio) > skip_for_load = !busiest_best_prio_seen && > head->next == head->prev; > if (skip_for_load || > !can_migrate_task(tmp, busiest, this_cpu, sd, idle, &pinned)) { > if (curr != head) > goto skip_queue; > idx++; > goto skip_bitmap; > } > > > What to do? Suresh's patch was wrong and this was intended as an alternative. Unfortunately, it is also in adequate and the setting of busiest_best_prio_seen needs to be moved to just after skip_for_load is set. I have another patch that does that (and adds to the comments). Should I send that separately or roll the two patches together? Peter -- Peter Williams pwil3058@bigpond.net.au "Learning, n. The kind of ignorance distinguishing the studious." -- Ambrose Bierce