From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46136) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dDx7t-0001S3-B5 for qemu-devel@nongnu.org; Thu, 25 May 2017 14:04:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dDx7q-0003EN-74 for qemu-devel@nongnu.org; Thu, 25 May 2017 14:04:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59348) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dDx7q-0003Dt-0p for qemu-devel@nongnu.org; Thu, 25 May 2017 14:04:42 -0400 Date: Thu, 25 May 2017 21:04:39 +0300 From: "Michael S. Tsirkin" Message-ID: <20170525210048-mutt-send-email-mst@kernel.org> References: <5922D0EC.6060405@intel.com> <5923C557.3020301@intel.com> <5924109F.6090608@intel.com> <48ec0c88-801f-fc1f-401f-51cb2ca3fed2@redhat.com> <592541D9.3030303@intel.com> <781faa1c-9253-d212-f616-2a899087edc1@redhat.com> <5926C519.6080508@intel.com> <2fb56ab7-99c6-ac30-de60-a747438416b8@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2fb56ab7-99c6-ac30-de60-a747438416b8@redhat.com> Subject: Re: [Qemu-devel] [virtio-dev] Re: [virtio-dev] Re: [PATCH RFC] virtio-net: enable configurable tx queue size List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang Cc: Wei Wang , virtio-dev@lists.oasis-open.org, stefanha@gmail.com, qemu-devel@nongnu.org, jan.scheurich@ericsson.com, marcandre.lureau@gmail.com, pbonzini@redhat.com On Thu, May 25, 2017 at 08:13:31PM +0800, Jason Wang wrote: > > > > The point of using the config field here is, when tomorrow's device is > > released with a requirement for the driver > > to use max_chain_size=1022 (not today's 1023), today's driver will > > naturally support tomorrow's device without > > any modification, since it reads the max_chain_size from the config > > field which is filled by the device (either today's > > device or tomorrow's device with different values). > > I'm not saying anything wrong with the config filed you introduced. But you > should answer the following question: > > Is it useful to support more than 1024? If yes, why? If not, introduce a > VIRTIO_F_SG_1024 is more than enough I think. > > Thanks I think it's useful to limit it below queue size too. -- MST