From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753455AbbJ0C6c (ORCPT ); Mon, 26 Oct 2015 22:58:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59496 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751573AbbJ0C6a (ORCPT ); Mon, 26 Oct 2015 22:58:30 -0400 Subject: Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list To: "Michael S. Tsirkin" References: <1445576225-27710-1-git-send-email-jasowang@redhat.com> <20151023163659-mutt-send-email-mst@redhat.com> <562D9AED.4060607@redhat.com> <20151026080851-mutt-send-email-mst@redhat.com> <562DCDF2.6030305@redhat.com> <20151026102928-mutt-send-email-mst@redhat.com> Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Vlad Yasevich From: Jason Wang Message-ID: <562EE851.40605@redhat.com> Date: Tue, 27 Oct 2015 10:58:25 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151026102928-mutt-send-email-mst@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/26/2015 04:30 PM, Michael S. Tsirkin wrote: > On Mon, Oct 26, 2015 at 02:53:38PM +0800, Jason Wang wrote: >> >> On 10/26/2015 02:09 PM, Michael S. Tsirkin wrote: >>> On Mon, Oct 26, 2015 at 11:15:57AM +0800, Jason Wang wrote: >>>> On 10/23/2015 09:37 PM, Michael S. Tsirkin wrote: >>>>> On Fri, Oct 23, 2015 at 12:57:05AM -0400, Jason Wang wrote: >>>>>> We don't have fraglist support in TAP_FEATURES. This will lead >>>>>> software segmentation of gro skb with frag list. Fixes by having >>>>>> frag list support in TAP_FEATURES. >>>>>> >>>>>> With this patch single session of netperf receiving were restored from >>>>>> about 5Gb/s to about 12Gb/s on mlx4. >>>>>> >>>>>> Fixes a567dd6252 ("macvtap: simplify usage of tap_features") >>>>>> Cc: Vlad Yasevich >>>>>> Cc: Michael S. Tsirkin >>>>>> Signed-off-by: Jason Wang >>>>> Thanks! >>>>> Does this mean we should look at re-adding NETIF_F_FRAGLIST >>>>> to virtio-net as well? >>>> Not sure I get the point, but probably not. This is for receiving and >>>> skb_copy_datagram_iter() can deal with frag list. >>> Point is: >>> - bridge within guest >>> - assigned device creating gro skbs with frag list bridged to virtio >> I see, but this problem looks not specific to virtio. Most cards does >> not support frag list. > These will be slower when used with a bridge then, won't they? For forwarding, not sure. GRO has latency and cpu overhead anyway. Anyway I can try to add the support for this.