[rhelv5-list] Lot's off TCP Window Ful , tuning ip possible?

["Bohmer, Andre ten" <Andre tenBohmer wur nl>]

Hello,

We've several smtp gateway servers based on rhel5.6 , running postfix and amongst others spamassasin (via mpp). Almost every 10 or 15 minutes or so, postfix logs an error:
postfix/smtpd[7258]: warning: timeout on 127.0.0.1:9998 while reading input attribute name

So it seems the service or server it too busy to honour this request.

Spitting through some loopback adapter tcpdump dump file's, reveals a lot of these kind of messages:

15:08:29.356265	127.0.0.1	127.0.0.1	TCP	[TCP Window Full] 47482 > distinct32 [ACK] S39 Win=32832 Len=96

Tcp auto-tuning is enabled :
$ cat /proc/sys/net/ipv4/tcp_moderate_rcvbuf  : 1

Any suggestions on tuning some ip / tcp kernel parameters or is everything handled via auto-tuning and we've reached the max of the servers capabilities?


Cheers,
Andre

---
Wageningen University and Research
The Netherlands
http://www.disclaimer-uk.wur.nl