From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758036Ab1KKQV0 (ORCPT ); Fri, 11 Nov 2011 11:21:26 -0500 Received: from cantor2.suse.de ([195.135.220.15]:39959 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756709Ab1KKQVZ (ORCPT ); Fri, 11 Nov 2011 11:21:25 -0500 Date: Fri, 11 Nov 2011 16:21:19 +0000 From: Mel Gorman To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH] mm: Reduce the amount of work done when updating min_free_kbytes Message-ID: <20111111162119.GP3083@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Signed-off-by: Mel Gorman --- mm/page_alloc.c | 35 +++++++++++++++++++---------------- 1 files changed, 19 insertions(+), 16 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 9dd443d..c95e4c9 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3401,25 +3401,28 @@ static void setup_zone_migrate_reserve(struct zone *zone) if (page_to_nid(page) != zone_to_nid(zone)) continue; - /* Blocks with reserved pages will never free, skip them. */ - block_end_pfn = min(pfn + pageblock_nr_pages, end_pfn); - if (pageblock_is_reserved(pfn, block_end_pfn)) - continue; - block_migratetype = get_pageblock_migratetype(page); - /* If this block is reserved, account for it */ - if (reserve > 0 && block_migratetype == MIGRATE_RESERVE) { - reserve--; - continue; - } + /* Only test what is necessary when the reserves are not met */ + if (reserve > 0) { + /* Blocks with reserved pages will never free, skip them. */ + block_end_pfn = min(pfn + pageblock_nr_pages, end_pfn); + if (pageblock_is_reserved(pfn, block_end_pfn)) + continue; - /* Suitable for reserving if this block is movable */ - if (reserve > 0 && block_migratetype == MIGRATE_MOVABLE) { - set_pageblock_migratetype(page, MIGRATE_RESERVE); - move_freepages_block(zone, page, MIGRATE_RESERVE); - reserve--; - continue; + /* If this block is reserved, account for it */ + if (block_migratetype == MIGRATE_RESERVE) { + reserve--; + continue; + } + + /* Suitable for reserving if this block is movable */ + if (block_migratetype == MIGRATE_MOVABLE) { + set_pageblock_migratetype(page, MIGRATE_RESERVE); + move_freepages_block(zone, page, MIGRATE_RESERVE); + reserve--; + continue; + } } /*