From: Wei Xu <address@hidden>
All the data packets in a tcp connection will be cached to a big buffer
in every receive interval, and will be sent out via a timer, the
'virtio_net_rsc_timeout' controls the interval, the value will
performance and response of tcp connection extremely, 50000(50us) is a
experience value to gain a performance improvement, since the whql test
sends packets every 100us, so '300000(300us)' can pass the test case,
this is also the default value, it's gonna to be tunable.
The timer will only be triggered if the packets pool is not empty,
and it'll drain off all the cached packets
'NetRscChain' is used to save the segments of different protocols in a
The main handler of TCP includes TCP window update, duplicated ACK
and the real data coalescing if the new segment passed sanity check
and is identified as an 'wanted' one.
An 'wanted' segment means:
1. Segment is within current window and the sequence is the expected
2. ACK of the segment is in the valid window.
3. If the ACK in the segment is a duplicated one, then it must less
this is to notify upper layer TCP starting retransmission due to
Sanity check includes:
1. Incorrect version in IP header
2. IP options & IP fragment
3. Not a TCP packets
4. Sanity size check to prevent buffer overflow attack.
There maybe more cases should be considered such as ip
flags, while it broke the test because windows set it to the same
not a fragment.
Normally it includes 2 typical ways to handle a TCP control flag,
and 'finalize', 'bypass' means should be sent out directly, and
means the packets should also be bypassed, and this should be done
after searching for the same connection packets in the pool and sending
all of them out, this is to avoid out of data.
All the 'SYN' packets will be bypassed since this always begin a new'
connection, other flags such 'FIN/RST' will trigger a finalization,
this normally happens upon a connection is going to be closed, an
also finalize current coalescing unit.
Statistics can be used to monitor the basic coalescing status, the
'out of order'
and 'out of window' means how many retransmitting packets, thus
Signed-off-by: Wei Xu <address@hidden>
hw/net/virtio-net.c | 480
include/hw/virtio/virtio-net.h | 1 +
include/hw/virtio/virtio.h | 72 +++++++
3 files changed, 552 insertions(+), 1 deletion(-)
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index bd91a4b..81e8e71 100644
@@ -15,10 +15,12 @@
@@ -38,6 +40,24 @@
#define endof(container, field) \
(offsetof(container, field) + sizeof(((container *)0)->field))
+#define VIRTIO_NET_IP4_ADDR_SIZE 8 /* ipv4 saddr + daddr */
+#define VIRTIO_NET_TCP_PORT_SIZE 4 /* sport + dport */
+/* IPv4 max payload, 16 bits in the header */
+#define VIRTIO_NET_MAX_IP4_PAYLOAD (65535 - sizeof(struct ip_header))
+#define VIRTIO_NET_MAX_TCP_PAYLOAD 65535
+/* header lenght value in ip header without option */