From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754101AbcAMQce (ORCPT ); Wed, 13 Jan 2016 11:32:34 -0500 Received: from mga14.intel.com ([192.55.52.115]:46389 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753979AbcAMQcX convert rfc822-to-8bit (ORCPT ); Wed, 13 Jan 2016 11:32:23 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,290,1449561600"; d="scan'208";a="892460573" Date: Wed, 13 Jan 2016 11:32:06 -0500 From: Matthew Wilcox To: "Chenjie (K)" Cc: Alexander Viro , linux-fsdevel@vger.kernel.org, zhihui.gao@huawei.com, linux-kernel@vger.kernel.org, lizefan@huawei.com, stable@vger.kernel.org Subject: Re: [PATCH] bugfix dax fault page should be no cache Message-ID: <20160113163206.GE8945@linux.intel.com> References: <1452599025-25489-1-git-send-email-chenjie6@huawei.com> <20160112125131.GB8945@linux.intel.com> <5695C8C0.1080005@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <5695C8C0.1080005@huawei.com> User-Agent: Mutt/1.5.24 (2015-08-30) Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 13, 2016 at 11:47:12AM +0800, Chenjie (K) wrote: > The DAX means Direct Access for files，if the pages have cache, > the file is not direct access. But in normal condition, > we can not find the problem directly. The file absolutely is direct accessed. The CPU cache is critical to performance, and should not be bypassed lightly. We have instructions to flush the cache, and a library (see http://pmem.io/) so that applications don't have to use them directly.