Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754544Ab3FQB4B (ORCPT ); Sun, 16 Jun 2013 21:56:01 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:44403 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753663Ab3FQBz7 (ORCPT ); Sun, 16 Jun 2013 21:55:59 -0400 X-IronPort-AV: E=Sophos;i="4.87,877,1363104000"; d="scan'208";a="7570620" Message-ID: <51BE6BFC.3030009@cn.fujitsu.com> Date: Mon, 17 Jun 2013 09:53:00 +0800 From: Zhang Yanfei User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.8) Gecko/20121012 Thunderbird/10.0.8 MIME-Version: 1.0 To: David Rientjes CC: Zhang Yanfei , Andrew Morton , Linux MM , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] mm: Add unlikely for current_order test References: <51BC4A83.50302@gmail.com> In-Reply-To: X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/06/17 09:53:55, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/06/17 09:53:58, Serialize complete at 2013/06/17 09:53:58 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1276 Lines: 35 Hi David, On 06/17/2013 02:04 AM, David Rientjes wrote: > On Sat, 15 Jun 2013, Zhang Yanfei wrote: > >> From: Zhang Yanfei >> >> Since we have an unlikely for the "current_order >= pageblock_order / 2" >> test above, adding an unlikely for this "current_order >= pageblock_order" >> test seems more appropriate. >> > > I don't understand the justification at all, current_order being unlikely > greater than or equal to pageblock_order / 2 doesn't imply at all that > it's unlikely that current_order is greater than or equal to > pageblock_order. > hmmm... I am confused. Since current_order is >= pageblock_order / 2 is unlikely, why current_order is >= pageblock_order isn't unlikely. Or there are other tips? Actually, I am also a little confused about why current_order should be unlikely greater than or equal to pageblock_order / 2. When borrowing pages with other migrate_type, we always search from MAX_ORDER-1, which is greater or equal to pageblock_order. -- Thanks. Zhang Yanfei -- 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/