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

From: Sergei Shtylyov
Date: Tue Jul 23 2013 - 08:12:58 EST


Hello.

On 23-07-2013 11:15, 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

s/memove/memmove/?

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@xxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
drivers/net/tun.c | 39 +++++++++++++++++++++++++++++++++++----
1 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index a72d141..66e265d 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
[...]
@@ -1328,11 +1330,39 @@ static ssize_t tun_put_user(struct tun_struct *tun,
total += tun->vnet_hdr_sz;
}

- len = min_t(int, skb->len, len);
+ if (!vlan_tx_tag_present(skb))
+ len = min_t(int, skb->len, len);
+ else {

According to Documentation/CodingStyle chapter 3, both arms of an *if* statement should have {} if one arm has it.

+ int copy, ret;
+ struct {
+ __be16 h_vlan_proto;
+ __be16 h_vlan_TCI;
+ } veth;

Empty line wouldn't hurt here, after declarations...

+ veth.h_vlan_proto = skb->vlan_proto;
+ veth.h_vlan_TCI = htons(vlan_tx_tag_get(skb));
[...]

WBR, Sergei

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/