Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964934AbWA3UAs (ORCPT ); Mon, 30 Jan 2006 15:00:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964937AbWA3UAs (ORCPT ); Mon, 30 Jan 2006 15:00:48 -0500 Received: from fmr21.intel.com ([143.183.121.13]:47274 "EHLO scsfmr001.sc.intel.com") by vger.kernel.org with ESMTP id S964934AbWA3UAr (ORCPT ); Mon, 30 Jan 2006 15:00:47 -0500 Date: Mon, 30 Jan 2006 12:00:26 -0800 From: "Luck, Tony" To: Ingo Molnar Cc: Bjorn Helgaas , Ingo Molnar , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Morton , Linus Torvalds Subject: Re: boot-time slowdown for measure_migration_cost Message-ID: <20060130200026.GA5081@agluck-lia64.sc.intel.com> References: <200601271403.27065.bjorn.helgaas@hp.com> <20060130172140.GB11793@elte.hu> <20060130185301.GA4622@agluck-lia64.sc.intel.com> <20060130192438.GA29129@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060130192438.GA29129@elte.hu> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1688 Lines: 50 On Mon, Jan 30, 2006 at 08:24:38PM +0100, Ingo Molnar wrote: > > Doing both gets the time down to 5.20s, and the migration_cost=9990. > > ok, that's good enough i think - we could certainly do the patch below > in v2.6.16. Might it be wise to see whether the 2% variation that I saw can be repeated on some other architecture? Bjorn's initial post was just questioning whether we need to spend this much time during boot to acquire this data. Now we have *one* data point that on an ia64 with four cpus with 9MB cache in a single domain that we can speed the calculation by a factor of three with only a 2% loss of accuracy. Can someone else try this patch and post the before/after values for migration_cost from dmesg? -Tony --- reduce the amount of time the migration cost calculations cost during bootup. Signed-off-by: Ingo Molnar --- linux/kernel/sched.c.orig +++ linux/kernel/sched.c @@ -5141,7 +5141,7 @@ static void init_sched_build_groups(stru #define SEARCH_SCOPE 2 #define MIN_CACHE_SIZE (64*1024U) #define DEFAULT_CACHE_SIZE (5*1024*1024U) -#define ITERATIONS 2 +#define ITERATIONS 1 #define SIZE_THRESH 130 #define COST_THRESH 130 @@ -5480,9 +5480,9 @@ static unsigned long long measure_migrat break; } /* - * Increase the cachesize in 5% steps: + * Increase the cachesize in 10% steps: */ - size = size * 20 / 19; + size = size * 10 / 9; } if (migration_debug) - 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/