From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f171.google.com (mail-ob0-f171.google.com [209.85.214.171]) by kanga.kvack.org (Postfix) with ESMTP id D94B56B0253 for ; Mon, 7 Mar 2016 01:29:21 -0500 (EST) Received: by mail-ob0-f171.google.com with SMTP id ts10so97515006obc.1 for ; Sun, 06 Mar 2016 22:29:21 -0800 (PST) Received: from tyo201.gate.nec.co.jp (TYO201.gate.nec.co.jp. [210.143.35.51]) by mx.google.com with ESMTPS id r200si8282130oie.31.2016.03.06.22.29.20 for (version=TLS1 cipher=AES128-SHA bits=128/128); Sun, 06 Mar 2016 22:29:21 -0800 (PST) From: Naoya Horiguchi Subject: Re: [PATCH v1 02/11] mm: thp: introduce CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION Date: Mon, 7 Mar 2016 06:28:54 +0000 Message-ID: <20160307062853.GA31458@hori1.linux.bs1.fc.nec.co.jp> References: <1456990918-30906-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1456990918-30906-3-git-send-email-n-horiguchi@ah.jp.nec.com> <20160307005804.GA25148@cotter.ozlabs.ibm.com> In-Reply-To: <20160307005804.GA25148@cotter.ozlabs.ibm.com> Content-Language: ja-JP Content-Type: text/plain; charset="iso-2022-jp" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Balbir Singh Cc: "linux-mm@kvack.org" , "Kirill A. Shutemov" , Hugh Dickins , Andrew Morton , Dave Hansen , Andrea Arcangeli , Mel Gorman , Michal Hocko , Vlastimil Babka , Pavel Emelyanov , "linux-kernel@vger.kernel.org" , Naoya Horiguchi On Mon, Mar 07, 2016 at 11:58:04AM +1100, Balbir Singh wrote: > On Thu, Mar 03, 2016 at 04:41:49PM +0900, Naoya Horiguchi wrote: > > Introduces CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION to limit thp migration > > functionality to x86_64, which should be safer at the first step. > > >=20 > The changelog is not helpful. Could you please describe what is > architecture specific in these changes? What do other arches need to do > to port these changes over? The arch specific parts are pmd_present() and swap entry format. Currently pmd_present() in x86_64 is not simple enough to easily determine pmd's stat= e (none, normal pmd entry pointing to pte page, pmd for thp, or pmd migration= entry ...) That requires me to assume in this version that pmd migration entry should have_PAGE_PSE set, which should not be necessary if the complexity is fixed= . So I will mention this pmd_present() problem in the next version. So if it's fixed, what developers need to do to port this feature to their architectures is just to enable CONFIG_ARCH_ENABLE_THP_MIGRATION (and test = it.) Thanks, Naoya Horiguchi= -- 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