From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753924AbaFJVVJ (ORCPT ); Tue, 10 Jun 2014 17:21:09 -0400 Received: from qmta09.emeryville.ca.mail.comcast.net ([76.96.30.96]:50284 "EHLO qmta09.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753665AbaFJVVI (ORCPT ); Tue, 10 Jun 2014 17:21:08 -0400 Date: Tue, 10 Jun 2014 16:21:04 -0500 (CDT) From: Christoph Lameter To: "Kirill A. Shutemov" cc: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Dave Hansen , Hugh Dickins , Mel Gorman , Rik van Riel , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH, RFC 00/10] THP refcounting redesign In-Reply-To: <20140610204640.GA9594@node.dhcp.inet.fi> Message-ID: References: <1402329861-7037-1-git-send-email-kirill.shutemov@linux.intel.com> <20140610204640.GA9594@node.dhcp.inet.fi> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 10 Jun 2014, Kirill A. Shutemov wrote: > Could you elaborate here? The page migration scheme works by locking and also putting in a fake pte to ensure that any accesses cause a page fault which will then block. In the THP case we would need a fake pmd. That allows effectively to force all accesses to the page to stop. Then you do the page migration (and you could do the splitting etc) and then replace the fake pmd/pte with real ones. See the page migration code. > Agreed. The patchset drops tail page refcounting. Great. Step in the right diretion. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f180.google.com (mail-qc0-f180.google.com [209.85.216.180]) by kanga.kvack.org (Postfix) with ESMTP id 2BDFE6B00D1 for ; Tue, 10 Jun 2014 17:21:09 -0400 (EDT) Received: by mail-qc0-f180.google.com with SMTP id i17so3103183qcy.25 for ; Tue, 10 Jun 2014 14:21:08 -0700 (PDT) Received: from qmta10.emeryville.ca.mail.comcast.net (qmta10.emeryville.ca.mail.comcast.net. [2001:558:fe2d:43:76:96:30:17]) by mx.google.com with ESMTP id 38si28285570qgr.2.2014.06.10.14.21.07 for ; Tue, 10 Jun 2014 14:21:08 -0700 (PDT) Date: Tue, 10 Jun 2014 16:21:04 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH, RFC 00/10] THP refcounting redesign In-Reply-To: <20140610204640.GA9594@node.dhcp.inet.fi> Message-ID: References: <1402329861-7037-1-git-send-email-kirill.shutemov@linux.intel.com> <20140610204640.GA9594@node.dhcp.inet.fi> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Dave Hansen , Hugh Dickins , Mel Gorman , Rik van Riel , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Tue, 10 Jun 2014, Kirill A. Shutemov wrote: > Could you elaborate here? The page migration scheme works by locking and also putting in a fake pte to ensure that any accesses cause a page fault which will then block. In the THP case we would need a fake pmd. That allows effectively to force all accesses to the page to stop. Then you do the page migration (and you could do the splitting etc) and then replace the fake pmd/pte with real ones. See the page migration code. > Agreed. The patchset drops tail page refcounting. Great. Step in the right diretion. -- 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