From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932388AbcHIRZm (ORCPT ); Tue, 9 Aug 2016 13:25:42 -0400 Received: from mga01.intel.com ([192.55.52.88]:21736 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932111AbcHIRZl (ORCPT ); Tue, 9 Aug 2016 13:25:41 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,495,1464678000"; d="scan'208";a="1011320637" From: "Huang\, Ying" To: Andrew Morton , , , , , "Kirill A . Shutemov" , Andrea Arcangeli Cc: "Huang\, Ying" , , Subject: Re: [RFC 00/11] THP swap: Delay splitting THP during swapping out References: <1470760673-12420-1-git-send-email-ying.huang@intel.com> Date: Tue, 09 Aug 2016 10:25:34 -0700 In-Reply-To: <1470760673-12420-1-git-send-email-ying.huang@intel.com> (Ying Huang's message of "Tue, 9 Aug 2016 09:37:42 -0700") Message-ID: <87k2fp4zxt.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 Hi, All, "Huang, Ying" writes: > From: Huang Ying > > This patchset is based on 8/4 head of mmotm/master. > > This is the first step for Transparent Huge Page (THP) swap support. > The plan is to delaying splitting THP step by step and avoid splitting > THP finally during THP swapping out and swapping in. > > The advantages of THP swap support are: > > - Batch swap operations for THP to reduce lock acquiring/releasing, > including allocating/freeing swap space, adding/deleting to/from swap > cache, and writing/reading swap space, etc. > > - THP swap space read/write will be 2M sequence IO. It is particularly > helpful for swap read, which usually are 4k random IO. > > - It will help memory fragmentation, especially when THP is heavily used > by the applications. 2M continuous pages will be free up after THP > swapping out. > > As the first step, in this patchset, the splitting huge page is > delayed from almost the first step of swapping out to after allocating > the swap space for THP and adding the THP into swap cache. This will > reduce lock acquiring/releasing for locks used for swap space and swap > cache management. For this patchset posting, In general, I want to check the basic design with memory management subsystem maintainers and developers. For [RFC 01/11] swap: Add swap_cluster_list, it is a cleanup patch. And I think it should be useful independently. I am not very confident about the memcg part, that is [RFC 03/11] mm, memcg: Add swap_cgroup_iter iterator [RFC 04/11] mm, memcg: Support to charge/uncharge multiple swap entries Please help me to check it. Best Regards, Huang, Ying