From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f51.google.com (mail-pa0-f51.google.com [209.85.220.51]) by kanga.kvack.org (Postfix) with ESMTP id 98A766B0038 for ; Thu, 31 Oct 2013 06:15:32 -0400 (EDT) Received: by mail-pa0-f51.google.com with SMTP id ld10so2275850pab.24 for ; Thu, 31 Oct 2013 03:15:32 -0700 (PDT) Received: from psmtp.com ([74.125.245.185]) by mx.google.com with SMTP id yk3si1747686pac.128.2013.10.31.03.15.30 for ; Thu, 31 Oct 2013 03:15:31 -0700 (PDT) Date: Thu, 31 Oct 2013 10:15:25 +0000 From: Mel Gorman Subject: Re: [PATCH] mm: get rid of unnecessary pageblock scanning in setup_zone_migrate_reserve Message-ID: <20131031101525.GT2400@suse.de> References: <1382562092-15570-1-git-send-email-kosaki.motohiro@gmail.com> <20131030151904.GO2400@suse.de> <527169BB.8020104@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <527169BB.8020104@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: KOSAKI Motohiro Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, KOSAKI Motohiro , Yasuaki Ishimatsu On Wed, Oct 30, 2013 at 04:19:07PM -0400, KOSAKI Motohiro wrote: > >@@ -3926,11 +3929,11 @@ static void setup_zone_migrate_reserve(struct zone *zone) > > /* > > * Reserve blocks are generally in place to help high-order atomic > > * allocations that are short-lived. A min_free_kbytes value that > >- * would result in more than 2 reserve blocks for atomic allocations > >- * is assumed to be in place to help anti-fragmentation for the > >- * future allocation of hugepages at runtime. > >+ * would result in more than MAX_MIGRATE_RESERVE_BLOCKS reserve blocks > >+ * for atomic allocations is assumed to be in place to help > >+ * anti-fragmentation for the future allocation of hugepages at runtime. > > */ > >- reserve = min(2, reserve); > >+ reserve = min(MAX_MIGRATE_RESERVE_BLOCKS, reserve); > > > > for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { > > if (!pfn_valid(pfn)) > >@@ -3956,6 +3959,7 @@ static void setup_zone_migrate_reserve(struct zone *zone) > > /* If this block is reserved, account for it */ > > if (block_migratetype == MIGRATE_RESERVE) { > > reserve--; > >+ found++; > > continue; > > } > > > >@@ -3970,6 +3974,10 @@ static void setup_zone_migrate_reserve(struct zone *zone) > > } > > } > > > >+ /* If all possible reserve blocks have been found, we're done */ > >+ if (found >= MAX_MIGRATE_RESERVE_BLOCKS) > >+ break; > >+ > > /* > > * If the reserve is met and this is a previous reserved block, > > * take it back > > Nit. I would like to add following hunk. This is just nit because moving > reserve pageblock is extreme rare. > > if (block_migratetype == MIGRATE_RESERVE) { > + found++; > set_pageblock_migratetype(page, MIGRATE_MOVABLE); > move_freepages_block(zone, page, MIGRATE_MOVABLE); > } I don't really see the advantage but if you think it is necessary then I do not object either. -- Mel Gorman SUSE Labs -- 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/ . Don't email: email@kvack.org