Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752561AbYKMLF5 (ORCPT ); Thu, 13 Nov 2008 06:05:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751703AbYKMLFr (ORCPT ); Thu, 13 Nov 2008 06:05:47 -0500 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:38869 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751671AbYKMLFq (ORCPT ); Thu, 13 Nov 2008 06:05:46 -0500 Message-ID: <491C0A01.5040106@jp.fujitsu.com> Date: Thu, 13 Nov 2008 20:05:37 +0900 From: Hidetoshi Seto User-Agent: Thunderbird 2.0.0.17 (Windows/20080914) MIME-Version: 1.0 To: linux-kernel@vger.kernel.org CC: Ingo Molnar , Paul Menage Subject: [PATCH] accelerate newidle balancing in relax_domain Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2271 Lines: 55 Increasing the value of 'sched_relax_domain_level' in cpuset expands the searching range of task balancing on some schedule events. As the result it makes the task balancing in the range more aggressive, so it will benefit some situation, such as where the latency is required even it sacrifices cache hit rate etc. (for such situation, it would be ideally best that cpus do not be idle until there are no runnable task.) This patch aimed to accelerate the balancing in the relax_domain. The newidle balancing is kicked when tasks in a runqueue run out. It finds and pulls runnable tasks from other busy cpus, checking load imbalance between cpus. Considering above situation, using loads in short term is preferred than that in long term because it makes balancing more aggressive otherwise it becomes relatively conservative. The referenced load is selected by the newidle_idx parameter of scheduler domains, so this patch tunes the parameters only when domains are in the relax_domain's range. There are no effects if you don't use relax_domain. Following is a result of my short-lightweight-transaction test, showing average of requester's latency (ms), 300 couple of threads running 30 sec on 8cpu/Itanium: 1) v2.6.28-rc4 Average 0.748783 Std Div 1.688022 Throughput 165313 2) v2.6.28-rc4 + relax_domain Average 0.536867 Std Div 1.115383 Throughput 168492 3) v2.6.28-rc4 + relax_domain + patch Average 0.385164 Std Div 0.801875 Throughput 170069 Signed-off-by: Hidetoshi Seto --- kernel/sched.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 57c933f..c970239 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -7366,6 +7366,8 @@ static void set_domain_attribute(struct sched_domain *sd, } else { /* turn on idle balance on this domain */ sd->flags |= (SD_WAKE_IDLE_FAR|SD_BALANCE_NEWIDLE); + /* make newidle balancing more aggressive */ + sd->newidle_idx = 0; } } -- 1.6.0.GIT -- 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/