[MUD-Dev] Re: Windows->Linux TCP/IP stack performance problems

[Alex Stewart]

J C Lawrence wrote:
> ------- Begin Forwarded Message
[...]
> Rhapsody, AIX, and appearantly Windoz behave like each other and
> presume that the slow start feature of TCP will initially send two
> segments. According to RFC 2001, TCP slow start should send only one
> segment.  Linux follows this RFC and the following situation unfolds:
> 
> non-RFC OS     sends http request.
> Linux          sends the first segment and waits for an ACK.
> non-RFC OS     waits 200ms for the seconds segment.
> non-RFC OS     gives up and sends ACK.
> Linux          sends more data...
[...]
> ------- End of Forwarded Message
[...]
> This may or may not affect your client operations.  Most likely it
> wouldn't as most client designs use long term connections (ie the rate
> of generating new connections is low) which is in direct contrast to
> web servers (where this impacts hard).  

It should be noted that slow-start is not just used for starting up a
connection.  While this may not be a large issue for many MUD implementations
either, slow-start will also be involved for already-open connections under
some congested network conditions (if packets start getting dropped).  Even
with persistent connections, therefore, this behavior can cause connection
performance to deteriorate even worse under already bad conditions for anything
which needs to send large amounts or bursts of data.

-alex
-------------------------------------------------------------------------------
     Alex Stewart - riche at crl.com - Richelieu @ Diversity University MOO
                         http://www.crl.com/~riche
           "For the world is hollow, and I have touched the sky."