[Twisted-Python] high server loads on FreeBSD - does kqueue reactor help?

Werner Thie wthie at thiengineering.ch
Tue Jan 20 04:50:47 EST 2009

Hi all

With a four core, four twisted http server processes (nevow/athena on 
top), dual 100 MBps interfaces, all four cores showing CPU loads of 50% 
  plus, I observe the following degradation in the network traffic with 

- 'TCP checksum incorrect' raising to almost 25% of all packets observed 
  from one client IP
- TCP Ack'ed lost segment raising to 0.5% of all packets observed

This was with poll reactor on FreeBSD 7.0

- Would it be of any help to switch to kqueue in this case?
- If so, is the documentation about using and patching PyKQueue-1.3 as 
given in


correct and up to date, given that on


the actual version mentioned is 1.2

Thanks in advance, Werner

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