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authorZhangjie \(HZ\) <zhangjie14@huawei.com>2014-04-29 18:43:22 +0800
committerDavid S. Miller <davem@davemloft.net>2014-04-30 13:31:26 -0400
commit6ebbc1a6383fe78be3c0961d1475043ac6cc2542 (patch)
tree434e55877e1085233ba57a3ecea22231030b80d2 /drivers/net/virtio_net.c
parent1621b94d2a655c8548ddbdfc8ccf907a5bbdc860 (diff)
virtio-net: Set needed_headroom for virtio-net when VIRTIO_F_ANY_LAYOUT is true
This is a small supplement for commit e7428e95a06fb516fac1308bd0e176e27c0b9287 ("virtio-net: put virtio-net header inline with data"). TCP packages have enough room to put virtio-net header in, but UDP packages do not. By setting dev->needed_headroom for virtio-net device, UDP packages could have enough room. For UDP packages, sk_buff is alloced in fun __ip_append_data. The size is "alloclen + hh_len + 15", and "hh_len = LL_RESERVED_SPACE(rt-dst.dev);". The Macro is defined as follows: #define LL_RESERVED_SPACE(dev) \ ((((dev)->hard_header_len+(dev)->needed_headroom)\ &~(HH_DATA_MOD - 1)) + HH_DATA_MOD) By default, for UDP packages, after skb is allocated, only 16 bytes reserved. And 2 bytes remained after mac header is set. That is not enough to put virtio-net header in. If we set dev->needed_headroom to 12 or 10 (according to mergeable_rx_bufs is on or off ), more room can be reserved. Then there is enough room for UDP packages to put the header in. test result list as below: guest and host: suse11sp3, netperf, intel 2.4GHz +-------+---------+---------+---------+---------+ | | old | new | +-------+---------+---------+---------+---------+ | UDP | Gbit/s | pps | Gbit/s | pps | | 64 | 0.57 | 692232 | 0.61 | 742420 | | 256 | 1.60 | 686860 | 1.71 | 733331 | | 512 | 2.92 | 674576 | 3.07 | 710446 | | 1024 | 4.99 | 598977 | 5.17 | 620821 | | 1460 | 5.68 | 483757 | 7.16 | 610519 | | 4096 | 6.98 | 637468 | 7.21 | 658471 | +-------+---------+---------+---------+---------+ Signed-off-by: Zhang Jie <zhangjie14@huawei.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Jason Wang <jasowang@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/virtio_net.c')
-rw-r--r--drivers/net/virtio_net.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8a852b5f215f..b852bb368acc 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1724,6 +1724,13 @@ static int virtnet_probe(struct virtio_device *vdev)
if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
vi->has_cvq = true;
+ if (vi->any_header_sg) {
+ if (vi->mergeable_rx_bufs)
+ dev->needed_headroom = sizeof(struct virtio_net_hdr_mrg_rxbuf);
+ else
+ dev->needed_headroom = sizeof(struct virtio_net_hdr);
+ }
+
/* Use single tx/rx queue pair as default */
vi->curr_queue_pairs = 1;
vi->max_queue_pairs = max_queue_pairs;