mirror of
https://github.com/apache/nuttx.git
synced 2026-08-02 20:59:02 +00:00
3fdcd065cf
when tcp retransmission only double conn->timer in Karn(tcp_timer.c L602), after retransmission in Jacobson
M is is now rtt test will become a negative value.
```
signed char m;
m = conn->rto - conn->timer; // M is now rtt test
/* This is taken directly from VJs original code in his paper */
m = m - (conn->sa >> 3);
conn->sa += m; //conn->sa is a negative value
if (m < 0)
{
m = -m;
}
m = m - (conn->sv >> 2);
conn->sv += m;
conn->rto = (conn->sa >> 3) + conn->sv; //rto
```
For example,we lost one ack packet, we will set conn->timer = 6 by backoff，conn->rto still 3.
After retransmission we will Do RTT estimation, then will get
```
conn->sa = 253
conn->rto = 46
```
Then if any packets lost it will wait for a long time before triggering a retransmission.
Test method.
We can reproduce this issue by adding drop ACK packets in tcp_input, and debug conn->rto after Jacobson.
Signed-off-by: meijian <meijian@xiaomi.com>
|
||
|---|---|---|
| .. | ||
| arp | ||
| bluetooth | ||
| can | ||
| devif | ||
| icmp | ||
| icmpv6 | ||
| ieee802154 | ||
| igmp | ||
| inet | ||
| ipfilter | ||
| ipforward | ||
| ipfrag | ||
| local | ||
| mld | ||
| nat | ||
| neighbor | ||
| netdev | ||
| netfilter | ||
| netlink | ||
| pkt | ||
| procfs | ||
| route | ||
| rpmsg | ||
| sixlowpan | ||
| socket | ||
| tcp | ||
| udp | ||
| usrsock | ||
| utils | ||
| CMakeLists.txt | ||
| Kconfig | ||
| Makefile | ||
| net_initialize.c | ||