a-lunev opened a new pull request #5242:
URL: https://github.com/apache/incubator-nuttx/pull/5242
## Summary
Both the snd_ackcb and snd_datacb callbacks were created and destroyed right
after sending every packet.
Whenever TCP_REXMIT event occurred due to TCP send timeout, TCP_REXMIT was
ignored because
snd_ackcb callback had been destroyed by the time.
The issue is fixed as follows:
- both the snd_ackcb and snd_datacb callbacks are combined into one snd_cb
callback
(the same way as in tcp_send_unbuffered.c).
- the snd_cb callback lives until all requested data (via sendfile) is sent,
including all ACKs and possible retransmissions.
As a positive side effect of the code optimization / fix, sendfile TCP
payload throughput is increased (the TCP payload throughput of tcp_sendfile is
increased from 234 Mbit/s up to about 432 Mbit/s (sim:tcpblaster config on my
Linux setup)).
## Impact
TCP sendfile
## Testing
Activate emulating packet loss on Linux host:
`$ sudo iptables -A INPUT -p tcp --dport 5471 -m statistic --mode random
--probability 0.01 -j DROP`
Build NuttX:
```
$ ./tools/configure.sh -l sim:tcpblaster
$ make menuconfig (enable CONFIG_NETUTILS_NETCAT_SENDFILE, disable
CONFIG_NET_TCP_WRITE_BUFFERS)
$ make
```
Enable TUN/TAP on Linux host:
```
$ sudo setcap cap_net_admin+ep ./nuttx
$ sudo ./tools/simhostroute.sh wlan0 on
```
Start iperf on Linux host:
`$ iperf -s -p 5471 -i 1 -w 416K`
Run NuttX on Linux host:
```
$ ./nuttx
NuttShell (NSH) NuttX-10.2.0
nsh> ifconfig eth0 10.0.1.2
nsh> ifup eth0
ifup eth0...OK
```
Start Wireshark (or tcpdump) and capture appeared tap0 interface.
Run netcat in NuttX:
```
nsh> dd if=/dev/zero of=/tmp/test.bin count=1000
nsh> netcat LINUX_HOST_IP_ADDRESS 5471 /tmp/test.bin
```
Observe packet loss -> TCP Retransmissions in TCP dump.
Deactivate emulating packet loss on Linux host:
`$ sudo iptables -D INPUT -p tcp --dport 5471 -m statistic --mode random
--probability 0.01 -j DROP`
Run netcat in NuttX:
```
nsh> dd if=/dev/zero of=/tmp/test.bin count=10000
nsh> netcat LINUX_HOST_IP_ADDRESS 5471 /tmp/test.bin
nsh> poweroff
```
iperf on Linux host:
```
$ iperf -s -p 5471 -i 1 -w 416K
------------------------------------------------------------
Server listening on TCP port 5471
TCP window size: 416 KByte
------------------------------------------------------------
[ 4] local 192.168.1.68 port 5471 connected with 10.0.1.2 port 25367
[ ID] Interval Transfer Bandwidth
[ 4] 0.0- 0.1 sec 4.88 MBytes 432 Mbits/sec
```
Disable TUN/TAP on Linux host:
`$ sudo ./tools/simhostroute.sh wlan0 off`
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