From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver Date: Tue, 17 Oct 2017 01:02:36 -0700 Message-ID: <20171017080236.GA27649@infradead.org> References: <20171012155027.3277-1-pagupta@redhat.com> <20171012155027.3277-3-pagupta@redhat.com> <20171017071633.GA9207@infradead.org> <1441791227.21027037.1508226056893.JavaMail.zimbra@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1441791227.21027037.1508226056893.JavaMail.zimbra@redhat.com> Sender: owner-linux-mm@kvack.org To: Pankaj Gupta Cc: Christoph Hellwig , kwolf@redhat.com, haozhong zhang , jack@suse.cz, xiaoguangrong eric , kvm@vger.kernel.org, david@redhat.com, linux-nvdimm@ml01.01.org, ross zwisler , linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, linux-mm@kvack.org, stefanha@redhat.com, pbonzini@redhat.com, dan j williams , nilal@redhat.com List-Id: linux-nvdimm@lists.01.org On Tue, Oct 17, 2017 at 03:40:56AM -0400, Pankaj Gupta wrote: > Are you saying do it as existing i.e ACPI pmem like interface? > The reason we have created this new driver is exiting pmem driver > does not define proper semantics for guest flushing requests. At this point I'm caring about the Linux-internal interface, and for that it should be integrated into the nvdimm subsystem and not a block driver. How the host <-> guest interface looks is a different idea. > > Regarding block support of driver, we want to achieve DAX support > to bypass guest page cache. Also, we want to utilize existing DAX > capable file-system interfaces(e.g fsync) from userspace file API's > to trigger the host side flush request. Well, if you want to support XFS+DAX better don't make it a block devices, because I'll post patches soon to stop using the block device entirely for the DAX case. -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934070AbdJQICt (ORCPT ); Tue, 17 Oct 2017 04:02:49 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:39021 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932628AbdJQICo (ORCPT ); Tue, 17 Oct 2017 04:02:44 -0400 Date: Tue, 17 Oct 2017 01:02:36 -0700 From: Christoph Hellwig To: Pankaj Gupta Cc: Christoph Hellwig , kwolf@redhat.com, haozhong zhang , jack@suse.cz, xiaoguangrong eric , kvm@vger.kernel.org, david@redhat.com, linux-nvdimm@ml01.01.org, ross zwisler , linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, linux-mm@kvack.org, stefanha@redhat.com, pbonzini@redhat.com, dan j williams , nilal@redhat.com Subject: Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver Message-ID: <20171017080236.GA27649@infradead.org> References: <20171012155027.3277-1-pagupta@redhat.com> <20171012155027.3277-3-pagupta@redhat.com> <20171017071633.GA9207@infradead.org> <1441791227.21027037.1508226056893.JavaMail.zimbra@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1441791227.21027037.1508226056893.JavaMail.zimbra@redhat.com> User-Agent: Mutt/1.8.3 (2017-05-23) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 17, 2017 at 03:40:56AM -0400, Pankaj Gupta wrote: > Are you saying do it as existing i.e ACPI pmem like interface? > The reason we have created this new driver is exiting pmem driver > does not define proper semantics for guest flushing requests. At this point I'm caring about the Linux-internal interface, and for that it should be integrated into the nvdimm subsystem and not a block driver. How the host <-> guest interface looks is a different idea. > > Regarding block support of driver, we want to achieve DAX support > to bypass guest page cache. Also, we want to utilize existing DAX > capable file-system interfaces(e.g fsync) from userspace file API's > to trigger the host side flush request. Well, if you want to support XFS+DAX better don't make it a block devices, because I'll post patches soon to stop using the block device entirely for the DAX case.