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[95.248.229.156]) by smtp.gmail.com with ESMTPSA id 5sm23670112qtp.81.2022.02.17.06.29.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Feb 2022 06:29:16 -0800 (PST) Date: Thu, 17 Feb 2022 15:29:10 +0100 From: Stefano Garzarella To: "Michael S. Tsirkin" , Gautam Dawar , eperezma@redhat.com Subject: Re: [PATCH 2/2] Allow VIRTIO_F_IN_ORDER to be negotiated for vdpa devices Message-ID: <20220217142910.eovyddvvpxkvzchf@sgarzare-redhat> References: <20220215072231.2498-1-gdawar@xilinx.com> <20220215072231.2498-3-gdawar@xilinx.com> <20220217023150-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: <20220217023150-mutt-send-email-mst@kernel.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=sgarzare@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline Received-SPF: pass client-ip=170.10.129.124; envelope-from=sgarzare@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jasowang@redhat.com, qemu-devel@nongnu.org, gdawar@xilinx.com, martinh@xilinx.com, hanand@xilinx.com, tanujk@xilinx.com, pabloc@xilinx.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Feb 17, 2022 at 02:32:48AM -0500, Michael S. Tsirkin wrote: >On Tue, Feb 15, 2022 at 12:52:31PM +0530, Gautam Dawar wrote: >> This patch adds the ability to negotiate VIRTIO_F_IN_ORDER bit >> for vhost-vdpa backend when the underlying device supports this >> feature. >> This would aid in reaping performance benefits with HW devices >> that implement this feature. At the same time, it shouldn't have >> any negative impact as vhost-vdpa backend doesn't involve any >> userspace virtqueue operations. >> >> Signed-off-by: Gautam Dawar > >Having features that hardware implements but qemu does not >means we can't migrate between them. >So I'd rather see a userspace implementation. FYI Jason proposed to support VIRTIO_F_IN_ORDER in QEMU/Linux as an idea for the next GSoC/Outreachy. I offered to mentor and prepared a project description [1], if anyone else is interested, it would be great to have a co-mentor :-) Thanks, Stefano [1] https://lists.gnu.org/archive/html/qemu-devel/2022-02/msg04032.html