netdev - Re: [PATCH net-next] tuntap: hardware vlan tx support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 23 Jul 2013 18:27:35 +0300
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Stephen Hemminger <stephen@...workplumber.org>
Cc:	Jason Wang <jasowang@...hat.com>, davem@...emloft.net,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Basil Gor <basil.gor@...il.com>
Subject: Re: [PATCH net-next] tuntap: hardware vlan tx support

On Tue, Jul 23, 2013 at 08:17:27AM -0700, Stephen Hemminger wrote:
> On Tue, 23 Jul 2013 15:15:48 +0800
> Jason Wang <jasowang@...hat.com> 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 <basil.gor@...il.com>
> > Cc: Michael S. Tsirkin <mst@...hat.com>
> > Signed-off-by: Jason Wang <jasowang@...hat.com>
> 
> 
> You need to make this configurable by some mechanism, since otherwise
> it will break applications that expect current VLAN behavior

I don't think there's a behavior change: vlan is still linearized
into the buffer. It's just done more efficiently.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html