From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756286Ab0CKJzA (ORCPT ); Thu, 11 Mar 2010 04:55:00 -0500 Received: from mail.gmx.net ([213.165.64.20]:45272 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755101Ab0CKJy6 (ORCPT ); Thu, 11 Mar 2010 04:54:58 -0500 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1+uk4YYj7KuA016awVOGbxe1jqXvjknk21/aJSh1c PK8JqETPWFCjTW Subject: Re: [patch 5/12] sched: tweak sched_latency and min_granularity From: Mike Galbraith To: Peter Zijlstra Cc: Ingo Molnar , LKML In-Reply-To: <1268300950.6785.27.camel@marge.simson.net> References: <1268300950.6785.27.camel@marge.simson.net> Content-Type: text/plain Date: Thu, 11 Mar 2010 10:54:45 +0100 Message-Id: <1268301285.6785.34.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 X-FuHaFi: 0.53000000000000003 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org sched: tweak sched_latency and min_granularity Allow LAST_BUDDY to kick in sooner, improving cache utilization as soon as a second buddy pair arrives on scene. The cost is latency starting to climb sooner, the tbenefit for tbench 8 on my Q6600 box is ~2%. No detrimental effects noted in normal idesktop usage. Signed-off-by: Mike Galbraith Cc: Ingo Molnar Cc: Peter Zijlstra LKML-Reference: --- kernel/sched_fair.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) Index: linux-2.6/kernel/sched_fair.c =================================================================== --- linux-2.6.orig/kernel/sched_fair.c +++ linux-2.6/kernel/sched_fair.c @@ -35,8 +35,8 @@ * (to see the precise effective timeslice length of your workload, * run vmstat and monitor the context-switches (cs) field) */ -unsigned int sysctl_sched_latency = 5000000ULL; -unsigned int normalized_sysctl_sched_latency = 5000000ULL; +unsigned int sysctl_sched_latency = 6000000ULL; +unsigned int normalized_sysctl_sched_latency = 6000000ULL; /* * The initial- and re-scaling of tunables is configurable @@ -52,15 +52,15 @@ enum sched_tunable_scaling sysctl_sched_ /* * Minimal preemption granularity for CPU-bound tasks: - * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds) + * (default: 2 msec * (1 + ilog(ncpus)), units: nanoseconds) */ -unsigned int sysctl_sched_min_granularity = 1000000ULL; -unsigned int normalized_sysctl_sched_min_granularity = 1000000ULL; +unsigned int sysctl_sched_min_granularity = 2000000ULL; +unsigned int normalized_sysctl_sched_min_granularity = 2000000ULL; /* * is kept at sysctl_sched_latency / sysctl_sched_min_granularity */ -static unsigned int sched_nr_latency = 5; +static unsigned int sched_nr_latency = 3; /* * After fork, child runs first. If set to 0 (default) then