From: "Zhangjie (HZ)" <zhangjie14@huawei•com>
To: <netdev@vger•kernel.org>
Cc: <jasowang@redhat•com>, <mst@redhat•com>, <qinchuanyu@huawei•com>,
<liuyongan@huawei•com>
Subject: [PATCH net-next] virtio-net: Set dev->needed_headroom for virtio-net device when it has the feature VIRTIO_F_ANY_LAYOUT
Date: Mon, 28 Apr 2014 21:05:57 +0800 [thread overview]
Message-ID: <535E5235.4000903@huawei.com> (raw)
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 | 0.573 | 692232 | 0.614 | 742420 |
| 256 | 1.6 | 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 |
+-------+---------+---------+---------+---------+
Signed-off-by: ZhangJie <zhangjie14@huawei•com>
---
drivers/net/virtio_net.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8a852b5..e18acc3 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;
--
1.7.1
next reply other threads:[~2014-04-28 13:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-28 13:05 Zhangjie (HZ) [this message]
2014-04-28 13:31 ` [PATCH net-next] virtio-net: Set dev->needed_headroom for virtio-net device when it has the feature VIRTIO_F_ANY_LAYOUT Michael S. Tsirkin
2014-04-28 13:48 ` Vlad Yasevich
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=535E5235.4000903@huawei.com \
--to=zhangjie14@huawei$(echo .)com \
--cc=jasowang@redhat$(echo .)com \
--cc=liuyongan@huawei$(echo .)com \
--cc=mst@redhat$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
--cc=qinchuanyu@huawei$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox