From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59393) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eb5FU-0006wt-5B for qemu-devel@nongnu.org; Mon, 15 Jan 2018 08:56:28 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eb5FQ-0008KN-7N for qemu-devel@nongnu.org; Mon, 15 Jan 2018 08:56:28 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51310) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eb5FQ-0008If-0u for qemu-devel@nongnu.org; Mon, 15 Jan 2018 08:56:24 -0500 Date: Mon, 15 Jan 2018 13:56:20 +0000 From: Stefan Hajnoczi Message-ID: <20180115135620.GG13238@stefanha-x1.localdomain> References: <20180110161438.GA28096@stefanha-x1.localdomain> <20180111152345.GA7353@stefanha-x1.localdomain> <86106573-422b-fe4c-ec15-dad0edf05880@redhat.com> <20180112101807.GE7356@stefanha-x1.localdomain> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="xjyYRNSh/RebjC6o" Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] vhost-pci and virtio-vhost-user List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang Cc: wei.w.wang@intel.com, qemu-devel@nongnu.org --xjyYRNSh/RebjC6o Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jan 15, 2018 at 02:56:31PM +0800, Jason Wang wrote: > On 2018=E5=B9=B401=E6=9C=8812=E6=97=A5 18:18, Stefan Hajnoczi wrote: > > > And what's more important, according to the kvm 2016 slides of vhost-= pci, > > > the motivation of vhost-pci is not building SDN but a chain of VNFs. = So > > > bypassing the central vswitch through a private VM2VM path does make = sense. > > > (Though whether or not vhost-pci is the best choice is still question= able). > > This is probably my fault. Maybe my networking terminology is wrong. I > > consider "virtual network functions" to be part of "software-defined > > networking" use cases. I'm not implying there must be a central virtual > > switch. > >=20 > > To rephrase: vhost-pci enables exitless VM2VM communication. >=20 > The problem is, exitless is not what vhost-pci invents, it could be achie= ved > now when both sides are doing busypolling. The only way I'm aware of is ivshmem. But ivshmem lacks a family of standard device types that allows different implementations to interoperate. We already have the virtio family of device types, so it makes sense to work on a virtio-based solution. Perhaps I've missed a different approach for exitless VM2VM communication. Please explain how VM1 and VM2 can do exitless network communication today? Also, how can VM1 provide SCSI I/O services to VM2 today? Stefan --xjyYRNSh/RebjC6o Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEcBAEBAgAGBQJaXLMEAAoJEJykq7OBq3PI9ooIALplKMZ1Lfking1jcIf30mX/ VZA2VVeuLk4BA48WFl0ATVKTK15rXffhdh7ozDEHXLBnm/o0gZrfTfWfwlknaZfP sXZrF0QU06Zgru+kFGUbUXuhdOI6Sn3Xq3kfgLHdVYBdF0tD0OsQ60ZdeEgI3S9+ k0AZ9zc6Nq7fd1OMo3ws2WL/zP1cZ9CvfzhDMFWc2rXDRFtn/Vsr2im9Al2FPGg/ aVLrSIh6iwp7BYTuDnsqeOaxRFdUNaq+zIiG+stm1HG/HDCw4jGo8rywMqsy17tb kKZ3pBRfKuSFIYnq5IXOpW7U928O6YLNLz3iRWviJ2V4tTGbPQGWFbokgKtnkNM= =bT53 -----END PGP SIGNATURE----- --xjyYRNSh/RebjC6o--