From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH net-next] tuntap: hardware vlan tx support Date: Wed, 24 Jul 2013 12:41:36 +0800 Message-ID: <51EF5B00.7040109@redhat.com> References: <1374563748-38821-1-git-send-email-jasowang@redhat.com> <20130723081727.69766d27@nehalam.linuxnetplumber.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Basil Gor To: Stephen Hemminger Return-path: In-Reply-To: <20130723081727.69766d27@nehalam.linuxnetplumber.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 07/23/2013 11:17 PM, Stephen Hemminger wrote: > On Tue, 23 Jul 2013 15:15:48 +0800 > Jason Wang wrote: > >> Inspired by commit f09e2249c4f5c7c13261ec73f5a7807076af0c8e (macvtap: restore >> vlan header on user read). This patch adds hardware vlan tx support for >> tuntap. This is done by copying vlan header directly into userspace in >> tun_put_user() instead of doing it through __vlan_put_tag() in >> dev_hard_start_xmit(). This eliminates one unnecessary memove in >> vlan_insert_tag() for 802.1ad and 802.1q traffic. >> >> pktgen test shows about 20% improvement for 802.1q traffic: >> >> Before: >> 662149pps 317Mb/sec (317831520bps) errors: 0 >> After: >> 801033pps 384Mb/sec (384495840bps) errors: 0 >> >> Cc: Basil Gor >> Cc: Michael S. Tsirkin >> Signed-off-by: Jason Wang > > You need to make this configurable by some mechanism, since otherwise > it will break applications that expect current VLAN behavior > -- > Didn't see any breakage. Vlan id will always exist in the userspace buffer.