From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758774AbcIHSHZ (ORCPT ); Thu, 8 Sep 2016 14:07:25 -0400 Received: from mga04.intel.com ([192.55.52.120]:26911 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754385AbcIHSHY (ORCPT ); Thu, 8 Sep 2016 14:07:24 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.30,301,1470726000"; d="scan'208";a="6229720" From: "Huang\, Ying" To: Anshuman Khandual Cc: "Huang\, Ying" , Andrew Morton , , , , , , , Hugh Dickins , Shaohua Li , Minchan Kim , Rik van Riel Subject: Re: [PATCH -v3 01/10] mm, swap: Make swap cluster size same of THP size on x86_64 References: <1473266769-2155-1-git-send-email-ying.huang@intel.com> <1473266769-2155-2-git-send-email-ying.huang@intel.com> <57D0FB10.5010609@linux.vnet.ibm.com> Date: Thu, 08 Sep 2016 11:07:20 -0700 In-Reply-To: <57D0FB10.5010609@linux.vnet.ibm.com> (Anshuman Khandual's message of "Thu, 8 Sep 2016 11:15:52 +0530") Message-ID: <87a8fi5kpz.fsf@yhuang-mobile.sh.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Anshuman Khandual writes: > On 09/07/2016 10:16 PM, Huang, Ying wrote: >> From: Huang Ying >> >> In this patch, the size of the swap cluster is changed to that of the >> THP (Transparent Huge Page) on x86_64 architecture (512). This is for >> the THP swap support on x86_64. Where one swap cluster will be used to >> hold the contents of each THP swapped out. And some information of the >> swapped out THP (such as compound map count) will be recorded in the >> swap_cluster_info data structure. >> >> For other architectures which want THP swap support, THP_SWAP_CLUSTER >> need to be selected in the Kconfig file for the architecture. >> >> In effect, this will enlarge swap cluster size by 2 times on x86_64. >> Which may make it harder to find a free cluster when the swap space >> becomes fragmented. So that, this may reduce the continuous swap space >> allocation and sequential write in theory. The performance test in 0day >> shows no regressions caused by this. > > This patch needs to be split into two separate ones > > (1) Add THP_SWAP_CLUSTER config option > (2) Enable CONFIG_THP_SWAP_CLUSTER for X86_64 > > The first patch should explain the proposal and the second patch > should have 86_64 arch specific details, regressions etc as already > been explained in the commit message. The code change and possible issues is not x86_64 specific, but general for all architectures where the config option is enabled. If so, the second patch becomes 1 line kconfig change and no much to be said in patch description. Does it deserve a separate patch? Best Regards, Huang, Ying