Re: [lwip-users] Performance issues when using the raw TCP API of lwIP

[Pomeroy, Marty]

>> I loaded up wireshark to see what was happening.
>> 
>> 192.168.1.26  is my desktop computer running windows.
>> 192.168.1.192 is the embedded system that's using lwIP. 
>>
>> 2578    207.992115    192.168.1.192    192.168.1.26    Gryphon    1422    - Invalid -
>> 2581    208.194336    192.168.1.26    192.168.1.192    TCP    54    afs3-fileserver > patrolview [ACK] Seq=1 Ack=1369 Win=64400 Len=0
>>  ...
>> 2588    208.200927    192.168.1.192    192.168.1.26    TCP    1314    [TCP segment of a reassembled PDU]
>> 2590    208.397469    192.168.1.26    192.168.1.192    TCP    54    afs3-fileserver > patrolview [ACK] Seq=1 Ack=8101 Win=63140 Len=0
>>
>> It seems that I currently send things quicker than the desktop is ACKing ...
>>  

200ms delays are a smoking gun for a Nagling problem on Windows.  In the registry, walk through the GUIDs at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\servic es\Tcpip\Parameters\Interfaces to find the IP address of the connection to the embedded system.  Then create two new values: TcpAckFrequency=1 (DWORD32) and TCPNoDelay=1 (DWORD32).

 

Here is a good discussion: http://lifeandcode.net/2009/05/reduce-game-network-latency-in-windows-7-or-vista/

 

There may also be other issues, but check that anyway.

 

Marty