From patchwork Tue Jul 17 22:37:20 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Nicholas A. Bellinger" X-Patchwork-Id: 1207361 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id B659FDF25A for ; Tue, 17 Jul 2012 22:37:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757183Ab2GQWhY (ORCPT ); Tue, 17 Jul 2012 18:37:24 -0400 Received: from mail.linux-iscsi.org ([67.23.28.174]:33839 "EHLO linux-iscsi.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751847Ab2GQWhW (ORCPT ); Tue, 17 Jul 2012 18:37:22 -0400 Received: from [192.168.0.116] (c-24-130-178-18.hsd1.ca.comcast.net [24.130.178.18]) (using SSLv3 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: nab) by linux-iscsi.org (Postfix) with ESMTPSA id 2E55822D9D0; Tue, 17 Jul 2012 22:34:33 +0000 (UTC) Subject: Re: [RFC-v2 0/4] tcm_vhost+cmwq fabric driver code for-3.6 From: "Nicholas A. Bellinger" To: "Michael S. Tsirkin" Cc: target-devel , linux-scsi , lf-virt , kvm-devel , Stefan Hajnoczi , Zhi Yong Wu , Anthony Liguori , Paolo Bonzini , Christoph Hellwig , Jens Axboe , Hannes Reinecke In-Reply-To: <20120717221814.GH1868@redhat.com> References: <1342041304-29728-1-git-send-email-nab@linux-iscsi.org> <20120717150548.GA11587@redhat.com> <1342559842.18004.440.camel@haakon2.linux-iscsi.org> <20120717213437.GC1868@redhat.com> <1342562528.18004.480.camel@haakon2.linux-iscsi.org> <20120717221814.GH1868@redhat.com> Date: Tue, 17 Jul 2012 15:37:20 -0700 Message-ID: <1342564640.18004.492.camel@haakon2.linux-iscsi.org> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, 2012-07-18 at 01:18 +0300, Michael S. Tsirkin wrote: > On Tue, Jul 17, 2012 at 03:02:08PM -0700, Nicholas A. Bellinger wrote: > > On Wed, 2012-07-18 at 00:34 +0300, Michael S. Tsirkin wrote: > > > On Tue, Jul 17, 2012 at 02:17:22PM -0700, Nicholas A. Bellinger wrote: > > > > On Tue, 2012-07-17 at 18:05 +0300, Michael S. Tsirkin wrote: > > > > > On Wed, Jul 11, 2012 at 09:15:00PM +0000, Nicholas A. Bellinger wrote: > > > > > > From: Nicholas Bellinger > > As mentioned in the response to Anthony, we are using the same generic > > fabric ABI in drivers/target/target_core_fabric_configfs.c since .38. > > > > That part is not going to change, and it has not changed for any of the > > other 7 target fabric modules we've merged into mainline since then. > > > > > > Also, tcm_vhost has been marked as Experimental following virtio-scsi. > > > > I'd much rather leave it at Experimental until we merge upstream > > > > userspace support. If userspace support never ends up materializing, > > > > I'm fine with dropping it all together. > > > > > > Once it's in kernel you never know who will use this driver. > > > Experimental does not mean driver can be dropped, staging does. > > > > > > > Yes, that's the point of being in mainline. People using the code, > > right..? > > Exactly. I am just worried about in the end being no major users and we > are being stuck with a niche driver that as a result is very hard to test. > And the reason for the fear is the initial negative reaction from the > qemu side. And no if it's there we can't just drop it. > That is certainly a reasonable concern.. > > > > However at this point given that there is a 3x performance gap between > > > > virtio-scsi-raw + virtio-scsi+tcm_vhost for random mixed small block > > > > I/O, and we still need the latter to do proper SCSI CDB passthrough for > > > > non TYPE_DISK devices I'm hoping that we can agree on userspace bits > > > > once tcm_vhost is merged. > > > > > > > > --nab > > > > > > I do think upstream kernel would help you nail userspace issues too > > > but at this point it looks like either staging meterial or 3.6 is too > > > early. > > > > > > > I think for-3.6 is just the right time for this kernel code. Seriously, > > The basic ABI fabric layout for /sys/kernel/config/target/vhost/ is > > going to be the same now for-3.6, the same for-3.7, and the same for .38 > > code. > > > > I'd be happy to move tcm_vhost back to drivers/target/ for now, and we > > move it to drivers/vhost/ once the userspace bits are worked out..? > > > > Would that be a reasonable compromise to move forward..? > > > > --nab > > I don't see how it helps. The driver is either a guaranteed ABI or not. > I'd prefer not to have vhost users outside drivers/vhost/ since it is > harder for me to keep track of them. > > What's the problem with staging proposal? It's just another hoop to jump > through to enable it? > Yeah, I'm OK with just adding a CONFIG_STAGING tag is a reasonable step forward for-3.6. Adding the following patch into target-pending/for-next-merge now: --- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig index ccbeb6f..2cd7135 100644 --- a/drivers/vhost/Kconfig +++ b/drivers/vhost/Kconfig @@ -11,7 +11,7 @@ config VHOST_NET config TCM_VHOST tristate "TCM_VHOST fabric module (EXPERIMENTAL)" - depends on TARGET_CORE && EVENTFD && EXPERIMENTAL && m + depends on TARGET_CORE && EVENTFD && EXPERIMENTAL && STAGING && m default n ---help--- Say M here to enable the TCM_VHOST fabric module for use with virtio-scsi guests