From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list Date: Mon, 26 Oct 2015 14:53:38 +0800 Message-ID: <562DCDF2.6030305@redhat.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Vlad Yasevich To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20151026080851-mutt-send-email-mst@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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.