From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH RFC 0/2] Packed ring for vhost Date: Wed, 14 Feb 2018 11:48:08 +0800 Message-ID: <97e20ab7-a73c-e911-f5ae-38359f68d4f4@redhat.com> References: <1518575829-1431-1-git-send-email-jasowang@redhat.com> <20180214044634-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, wexu@redhat.com, jfreimann@redhat.com, tiwei.bie@intel.com To: "Michael S. Tsirkin" Return-path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:42102 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S966671AbeBNDsY (ORCPT ); Tue, 13 Feb 2018 22:48:24 -0500 In-Reply-To: <20180214044634-mutt-send-email-mst@kernel.org> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 2018年02月14日 10:47, Michael S. Tsirkin wrote: > On Wed, Feb 14, 2018 at 10:37:07AM +0800, Jason Wang wrote: >> Hi all: >> >> This RFC implement a subset of packed ring which was described at >> https://github.com/oasis-tcs/virtio-docs/blob/master/virtio-v1.1-packed-wd07.pdf >> . The code were tested with pmd implement by Jens at >> http://dpdk.org/ml/archives/dev/2018-January/089417.html. Minor >> change was needed for pmd codes to kick virtqueue since it assumes a >> busy polling backend. >> >> Test were done between localhost and guest. Testpmd (rxonly) in guest >> reports 2.4Mpps. Testpmd (txonly) repots about 2.1Mpps. > How does this compare with the split ring design? No obvious difference (+-5%). I believe we reach the bottleneck of vhost. > >> It's not a complete implemention, here's what were missed: >> >> - Device Area >> - Driver Area >> - Descriptor indirection >> - Zerocopy may not be functional >> - Migration path is not tested >> - Vhost devices except for net >> - vIOMMU can not work (mainly because the metadata prefetch is not >> implemented). >> - See FIXME/TODO in the codes for more details >> - No batching or other optimizations were implemented > ioeventfd for PIO/mmio/s390. > Probably, but this is not the stuffs of packed ring I think. Thanks