Forum: CFEngine Help
Subject: What kernel tunables do you implement for better Cfengine performance?
Author: msvob...@linkedin.com
Link to topic: https://cfengine.com/forum/read.php?3,24620,24620#msg-24620
I had the oppretunity to meet with Mark Burgess last week at LinkedIn and we
had a brief discussion about cf-serverd performance. He stated that TCP
tuning Linux systems can give dramatic performance gains to cf-serverd.
The one TCP kernel tunable he suggested was net.ipv4.tcp_fin_timeout. Looking
at a current RHEL6 machine, this is set to the default 60s.
>From the kernel documentation:
tcp_fin_timeout - INTEGER
Time to hold socket in state FIN-WAIT-2, if it was closed
by our side. Peer can be broken and never close its side,
or even died unexpectedly. Default value is 60sec.
Usual value used in 2.2 was 180 seconds, you may restore
it, but remember that if your machine is even underloaded WEB server,
you risk to overflow memory with kilotons of dead sockets,
FIN-WAIT-2 sockets are less dangerous than FIN-WAIT-1,
because they eat maximum 1.5K of memory, but they tend
to live longer. Cf. tcp_max_orphans.
Does anyone else tune their Linux / Solaris TCP stack for improved performance,
and if so, what changes have you found to give better performance? Valid
answers win a cookie or metal award. I'll attempt to implement these tunables
on our non-production instance serving several hundred clients. If I can
dramatically cut down on network transfer times, then you'll seriously be a
Cfengine hero.
Cheers
Mike
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