From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pankaj Gupta Subject: Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver Date: Tue, 17 Oct 2017 04:30:41 -0400 (EDT) Message-ID: <670833322.21037148.1508229041158.JavaMail.zimbra@redhat.com> References: <20171012155027.3277-1-pagupta@redhat.com> <20171012155027.3277-3-pagupta@redhat.com> <20171017071633.GA9207@infradead.org> <1441791227.21027037.1508226056893.JavaMail.zimbra@redhat.com> <20171017080236.GA27649@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20171017080236.GA27649@infradead.org> Sender: owner-linux-mm@kvack.org To: Christoph Hellwig Cc: 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 > > 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. o.k I will look at your patches once they are in mailing list. Thanks for the heads up. If I am guessing it right, we don't need block device additional features for pmem? We can bypass block device features like blk device cache flush etc. Also, still we would be supporting ext4 & XFS filesystem with pmem? If there is time to your patches can you please elaborate on this a bit. Thanks, Pankaj -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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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 S1759475AbdJQIav (ORCPT ); Tue, 17 Oct 2017 04:30:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55102 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753302AbdJQIaq (ORCPT ); Tue, 17 Oct 2017 04:30:46 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com BE3EC81DF4 Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=pagupta@redhat.com Date: Tue, 17 Oct 2017 04:30:41 -0400 (EDT) From: Pankaj Gupta To: Christoph Hellwig Cc: 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 Message-ID: <670833322.21037148.1508229041158.JavaMail.zimbra@redhat.com> In-Reply-To: <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> <20171017080236.GA27649@infradead.org> Subject: Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.116.151, 10.4.195.21] Thread-Topic: add virtio-pmem driver Thread-Index: Nl7QQpQKXbcIb+heNFDWk4ouVYZ/Cg== X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Tue, 17 Oct 2017 08:30:45 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > 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. o.k I will look at your patches once they are in mailing list. Thanks for the heads up. If I am guessing it right, we don't need block device additional features for pmem? We can bypass block device features like blk device cache flush etc. Also, still we would be supporting ext4 & XFS filesystem with pmem? If there is time to your patches can you please elaborate on this a bit. Thanks, Pankaj