From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60880) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dLoAp-0004J9-1y for qemu-devel@nongnu.org; Fri, 16 Jun 2017 06:08:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dLoAl-0005nE-Ra for qemu-devel@nongnu.org; Fri, 16 Jun 2017 06:08:15 -0400 Received: from mga03.intel.com ([134.134.136.65]:14472) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dLoAl-0005kr-Hv for qemu-devel@nongnu.org; Fri, 16 Jun 2017 06:08:11 -0400 Message-ID: <5943AE93.7020502@intel.com> Date: Fri, 16 Jun 2017 18:10:27 +0800 From: Wei Wang MIME-Version: 1.0 References: <593F8153.7080209@intel.com> <593F9187.6040800@intel.com> <9f196d71-f06b-7520-ca03-e94bf3b5a986@redhat.com> <593FB550.6090903@intel.com> <26250da7-b394-4964-8842-5c45bbe85e09@redhat.com> <6547dfcf-ea3a-f5f6-222d-40ff274654df@redhat.com> <20170614180459-mutt-send-email-mst@kernel.org> <59422E91.7080407@intel.com> <20170616061949-mutt-send-email-mst@kernel.org> <40a12829-6e84-e63e-ac47-6f09cc85c3cc@redhat.com> In-Reply-To: <40a12829-6e84-e63e-ac47-6f09cc85c3cc@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [virtio-dev] Re: [virtio-dev] Re: [virtio-dev] Re: [PATCH v1] virtio-net: enable configurable tx queue size List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang , "Michael S. Tsirkin" Cc: "virtio-dev@lists.oasis-open.org" , "stefanha@gmail.com" , "qemu-devel@nongnu.org" , "jan.scheurich@ericsson.com" , "armbru@redhat.com" , "marcandre.lureau@gmail.com" , "pbonzini@redhat.com" On 06/16/2017 04:57 PM, Jason Wang wrote: > > > On 2017年06月16日 11:22, Michael S. Tsirkin wrote: >>> I think the issues can be solved by VIRTIO_F_MAX_CHAIN_SIZE. >>> >>> For now, how about splitting it into two series of patches: >>> 1) enable 1024 tx queue size for vhost-user, to let the users of >>> vhost-user >>> to easily use 1024 queue size. >> Fine with me. 1) will get property from user but override it on >> !vhost-user. Do we need a protocol flag? It seems prudent but we get >> back to cross-version migration issues that are still pending solution. What do you have in mind about the protocol flag? Btw, I just tested the patch of 1), and it works fine with migration from the patched to non-patched version of QEMU. I'll send it out. Please have a check. >> Marc Andre, what's the status of that work? >> >>> 2) enable VIRTIO_F_MAX_CHAIN_SIZE, to enhance robustness. >> Rather, to support it for more backends. > > Ok, if we want to support different values of max chain size in the > future. It would be problematic for migration of cross backends, > consider the case when migrating from 2048 (vhost-user) to 1024 > (qemu/vhost-kernel). > I think that wouldn't be a problem. If there is a possibility to change the backend resulting in a change of config.max_change_size, a configuration change notification can be injected to the guest, then guest will read and get the new value. Best, Wei