From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759598Ab3HNI5S (ORCPT ); Wed, 14 Aug 2013 04:57:18 -0400 Received: from cantor2.suse.de ([195.135.220.15]:56821 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759559Ab3HNI5Q (ORCPT ); Wed, 14 Aug 2013 04:57:16 -0400 Date: Wed, 14 Aug 2013 09:57:11 +0100 From: Mel Gorman To: Xishi Qiu Cc: Andrew Morton , riel@redhat.com, Minchan Kim , aquini@redhat.com, linux-mm@kvack.org, LKML Subject: Re: [PATCH] mm: skip the page buddy block instead of one page Message-ID: <20130814085711.GK2296@suse.de> References: <520B0B75.4030708@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <520B0B75.4030708@huawei.com> 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 On Wed, Aug 14, 2013 at 12:45:41PM +0800, Xishi Qiu wrote: > A large free page buddy block will continue many times, so if the page > is free, skip the whole page buddy block instead of one page. > > Signed-off-by: Xishi Qiu page_order cannot be used unless zone->lock is held which is not held in this path. Acquiring the lock would prevent parallel allocations from the buddy allocator (per-cpu allocator would be ok except for refills). I expect it would not be a good tradeoff to acquire the lock just to use page_order. Nak. -- Mel Gorman SUSE Labs