From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752659AbcBLSg1 (ORCPT ); Fri, 12 Feb 2016 13:36:27 -0500 Received: from mga01.intel.com ([192.55.52.88]:1820 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751242AbcBLSg0 (ORCPT ); Fri, 12 Feb 2016 13:36:26 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,436,1449561600"; d="scan'208";a="910911870" Subject: Re: [PATCHv2 15/28] thp: handle file COW faults To: "Kirill A. Shutemov" , Hugh Dickins , Andrea Arcangeli , Andrew Morton References: <1455200516-132137-1-git-send-email-kirill.shutemov@linux.intel.com> <1455200516-132137-16-git-send-email-kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka , Christoph Lameter , Naoya Horiguchi , Jerome Marchand , Yang Shi , Sasha Levin , linux-kernel@vger.kernel.org, linux-mm@kvack.org From: Dave Hansen Message-ID: <56BE2629.90001@intel.com> Date: Fri, 12 Feb 2016 10:36:25 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <1455200516-132137-16-git-send-email-kirill.shutemov@linux.intel.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 02/11/2016 06:21 AM, Kirill A. Shutemov wrote: > File COW for THP is handled on pte level: just split the pmd. More changelog. More comments, please. We don't want to COW THP's because we'll waste memory? A COW that we could handle with 4k, we would have to handle with 2M, and that's inefficient and high-latency? Seems like a good idea to me. It would just be nice to ensure every reviewer doesn't have to think their way through it.