From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f54.google.com (mail-pa0-f54.google.com [209.85.220.54]) by kanga.kvack.org (Postfix) with ESMTP id 24FA86B0256 for ; Mon, 3 Aug 2015 00:10:11 -0400 (EDT) Received: by padck2 with SMTP id ck2so79378121pad.0 for ; Sun, 02 Aug 2015 21:10:10 -0700 (PDT) Received: from mga14.intel.com (mga14.intel.com. [192.55.52.115]) by mx.google.com with ESMTP id ys2si10635296pbc.207.2015.08.02.21.10.09 for ; Sun, 02 Aug 2015 21:10:10 -0700 (PDT) Message-ID: <55BEE99E.8090901@intel.com> Date: Sun, 02 Aug 2015 21:10:06 -0700 From: Dave Hansen MIME-Version: 1.0 Subject: Re: [PATCH] mm: add the block to the tail of the list in expand() References: <55BB4027.7080200@huawei.com> <55BC0392.2070205@intel.com> <55BECC85.7050206@huawei.com> In-Reply-To: <55BECC85.7050206@huawei.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Xishi Qiu Cc: Andrew Morton , Mel Gorman , Vlastimil Babka , Johannes Weiner , Michal Hocko , iamjoonsoo.kim@lge.com, alexander.h.duyck@redhat.com, sasha.levin@oracle.com, Linux MM , LKML On 08/02/2015 07:05 PM, Xishi Qiu wrote: >> > Also, this might not do very much good in practice. If you are >> > splitting a high-order page, you are doing the split because the >> > lower-order lists are empty. So won't that list_add() be to an empty > > I made a mistake, you are right, all the lower-order lists are empty, > so it is no sense to add to the tail. I actually tested this experimentally and the lists are not always empty. It's probably __rmqueue_smallest() vs. __rmqueue_fallback() logic. In any case, you might want to double-check. -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752131AbbHCEKL (ORCPT ); Mon, 3 Aug 2015 00:10:11 -0400 Received: from mga01.intel.com ([192.55.52.88]:13368 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751339AbbHCEKK (ORCPT ); Mon, 3 Aug 2015 00:10:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,598,1432623600"; d="scan'208";a="776510229" Message-ID: <55BEE99E.8090901@intel.com> Date: Sun, 02 Aug 2015 21:10:06 -0700 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.8.0 MIME-Version: 1.0 To: Xishi Qiu CC: Andrew Morton , Mel Gorman , Vlastimil Babka , Johannes Weiner , Michal Hocko , iamjoonsoo.kim@lge.com, alexander.h.duyck@redhat.com, sasha.levin@oracle.com, Linux MM , LKML Subject: Re: [PATCH] mm: add the block to the tail of the list in expand() References: <55BB4027.7080200@huawei.com> <55BC0392.2070205@intel.com> <55BECC85.7050206@huawei.com> In-Reply-To: <55BECC85.7050206@huawei.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/02/2015 07:05 PM, Xishi Qiu wrote: >> > Also, this might not do very much good in practice. If you are >> > splitting a high-order page, you are doing the split because the >> > lower-order lists are empty. So won't that list_add() be to an empty > > I made a mistake, you are right, all the lower-order lists are empty, > so it is no sense to add to the tail. I actually tested this experimentally and the lists are not always empty. It's probably __rmqueue_smallest() vs. __rmqueue_fallback() logic. In any case, you might want to double-check.