From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id B87B46B002D for ; Mon, 14 Nov 2011 18:21:02 -0500 (EST) Date: Mon, 14 Nov 2011 15:21:00 -0800 From: Andrew Morton Subject: Re: [PATCH] mm: Reduce the amount of work done when updating min_free_kbytes Message-Id: <20111114152100.1333a015.akpm@linux-foundation.org> In-Reply-To: <20111111162119.GP3083@suse.de> References: <20111111162119.GP3083@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org On Fri, 11 Nov 2011 16:21:19 +0000 Mel Gorman wrote: > When min_free_kbytes is updated, some pageblocks are marked MIGRATE_RESERVE. > Ordinarily, this work is unnoticable as it happens early in boot but on > large machines with 1TB of memory, this has been reported to delay > boot times, probably due to the NUMA distances involved. > > The bulk of the work is due to calling calling pageblock_is_reserved() > an unnecessary amount of times and accessing far more struct page > metadata than is necessary. This patch significantly reduces the > amount of work done by setup_zone_migrate_reserve() improving boot > times on 1TB machines. > By how much? :) (I mainly ask because I'm curious to know how long the kernel takes to boot on a 1TB machine...) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org