From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 00/13] dax, pmem: move cpu cache maintenance to libnvdimm Date: Sun, 22 Jan 2017 19:44:39 +0100 Message-ID: <20170122184439.GA7603@lst.de> References: <148488421301.37913.12835362165895864897.stgit@dwillia2-desk3.amr.corp.intel.com> <20170121175212.GA28180@lst.de> <20170122162910.GA5267@lst.de> <20170122183046.GA7359@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" To: Matthew Wilcox Cc: Jens Axboe , Tony Luck , Jan Kara , Mike Snitzer , "linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org" , "x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Ingo Molnar , Thomas Gleixner , Al Viro , "H. Peter Anvin" , "linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org" , Linus Torvalds , Christoph Hellwig List-Id: dm-devel.ids On Sun, Jan 22, 2017 at 06:39:28PM +0000, Matthew Wilcox wrote: > Two guests on the same physical machine (or a guest and a host) have access to the same set of physical addresses. This might be an NV-DIMM, or it might just be DRAM (for the purposes of reducing guest overhead). The network filesystem has been enhanced with a call to allow the client to ask the server "What is the physical address for this range of bytes in this file?" > > We don't want to use the guest pagecache here. That's antithetical to the second usage, and it's inefficient for the first usage. And the answer is that you need a dax device for whatever memoery exposed in this way, as it needs to show up in the memory map for example. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from newverein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id C4C9081ECF for ; Sun, 22 Jan 2017 10:44:40 -0800 (PST) Date: Sun, 22 Jan 2017 19:44:39 +0100 From: Christoph Hellwig Subject: Re: [PATCH 00/13] dax, pmem: move cpu cache maintenance to libnvdimm Message-ID: <20170122184439.GA7603@lst.de> References: <148488421301.37913.12835362165895864897.stgit@dwillia2-desk3.amr.corp.intel.com> <20170121175212.GA28180@lst.de> <20170122162910.GA5267@lst.de> <20170122183046.GA7359@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Matthew Wilcox Cc: Jens Axboe , Tony Luck , Jan Kara , Mike Snitzer , "linux-nvdimm@lists.01.org" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , Ingo Molnar , Thomas Gleixner , Al Viro , "H. Peter Anvin" , "linux-fsdevel@vger.kernel.org" , "dm-devel@redhat.com" , Linus Torvalds , Christoph Hellwig List-ID: On Sun, Jan 22, 2017 at 06:39:28PM +0000, Matthew Wilcox wrote: > Two guests on the same physical machine (or a guest and a host) have access to the same set of physical addresses. This might be an NV-DIMM, or it might just be DRAM (for the purposes of reducing guest overhead). The network filesystem has been enhanced with a call to allow the client to ask the server "What is the physical address for this range of bytes in this file?" > > We don't want to use the guest pagecache here. That's antithetical to the second usage, and it's inefficient for the first usage. And the answer is that you need a dax device for whatever memoery exposed in this way, as it needs to show up in the memory map for example. _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Sun, 22 Jan 2017 19:44:39 +0100 From: Christoph Hellwig To: Matthew Wilcox Cc: Christoph Hellwig , Dan Williams , "linux-nvdimm@lists.01.org" , Brian Boylston , Tony Luck , Jan Kara , Toshi Kani , Mike Snitzer , "linux-kernel@vger.kernel.org" , "x86@kernel.org" , Jeff Moyer , Jens Axboe , "dm-devel@redhat.com" , Ingo Molnar , Al Viro , "H. Peter Anvin" , "linux-fsdevel@vger.kernel.org" , Thomas Gleixner , Linus Torvalds , Ross Zwisler Subject: Re: [PATCH 00/13] dax, pmem: move cpu cache maintenance to libnvdimm Message-ID: <20170122184439.GA7603@lst.de> References: <148488421301.37913.12835362165895864897.stgit@dwillia2-desk3.amr.corp.intel.com> <20170121175212.GA28180@lst.de> <20170122162910.GA5267@lst.de> <20170122183046.GA7359@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: On Sun, Jan 22, 2017 at 06:39:28PM +0000, Matthew Wilcox wrote: > Two guests on the same physical machine (or a guest and a host) have access to the same set of physical addresses. This might be an NV-DIMM, or it might just be DRAM (for the purposes of reducing guest overhead). The network filesystem has been enhanced with a call to allow the client to ask the server "What is the physical address for this range of bytes in this file?" > > We don't want to use the guest pagecache here. That's antithetical to the second usage, and it's inefficient for the first usage. And the answer is that you need a dax device for whatever memoery exposed in this way, as it needs to show up in the memory map for example. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751774AbdAVSos (ORCPT ); Sun, 22 Jan 2017 13:44:48 -0500 Received: from verein.lst.de ([213.95.11.211]:60784 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750999AbdAVSok (ORCPT ); Sun, 22 Jan 2017 13:44:40 -0500 Date: Sun, 22 Jan 2017 19:44:39 +0100 From: Christoph Hellwig To: Matthew Wilcox Cc: Christoph Hellwig , Dan Williams , "linux-nvdimm@lists.01.org" , Brian Boylston , Tony Luck , Jan Kara , Toshi Kani , Mike Snitzer , "linux-kernel@vger.kernel.org" , "x86@kernel.org" , Jeff Moyer , Jens Axboe , "dm-devel@redhat.com" , Ingo Molnar , Al Viro , "H. Peter Anvin" , "linux-fsdevel@vger.kernel.org" , Thomas Gleixner , Linus Torvalds , Ross Zwisler Subject: Re: [PATCH 00/13] dax, pmem: move cpu cache maintenance to libnvdimm Message-ID: <20170122184439.GA7603@lst.de> References: <148488421301.37913.12835362165895864897.stgit@dwillia2-desk3.amr.corp.intel.com> <20170121175212.GA28180@lst.de> <20170122162910.GA5267@lst.de> <20170122183046.GA7359@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 22, 2017 at 06:39:28PM +0000, Matthew Wilcox wrote: > Two guests on the same physical machine (or a guest and a host) have access to the same set of physical addresses. This might be an NV-DIMM, or it might just be DRAM (for the purposes of reducing guest overhead). The network filesystem has been enhanced with a call to allow the client to ask the server "What is the physical address for this range of bytes in this file?" > > We don't want to use the guest pagecache here. That's antithetical to the second usage, and it's inefficient for the first usage. And the answer is that you need a dax device for whatever memoery exposed in this way, as it needs to show up in the memory map for example.