On Thu, 25 Apr 2002, Thomas Flynn wrote:
> I'm attempting to use polymix-3 using polygraph-2.5.4 on a Sunfire
> 280r running Solaris 8. This machine has the new UltraSparc III
> 900Mhz chips. Previous test on other Sun boxes give us a hit on
> the cache around 200 msec on average. I'm seeing up to 500 msec on
> this box. The only thing I'm see right away is this system seems
> to have alot of tcp connections in a TIME_WAIT state. I've tweaked
> the tcp_wait_time_interval parameter to 1 sec. No avail. Am
> wondering if anyone has any ideas or has seen this before...
I bet that your older system was tuned differently or had different
defaults for some of the performance-related settings.
Disclaimer: I do not know Solaris. Hopefully you will get better
answers from Solaris gurus on the list. I have two guesses. The first
one is much better than the second, but both are guesses.
First, I would check your settings for delayed ACKs. Enabling delayed
ACKs may cause 200msec increase in response time in certain
environments. See "tcp_deferred_ack_interval" setting and disable
delayed ACKs.
Second, I assume you are tuning "tcp_time_wait_interval" setting.
Since that variable specifies TIME_WAIT duration, and TIME_WAIT is
2*MSL, I wonder whether your 1sec setting is too low. That is, I
wonder whether Solaris tries to divide 1 by two, gets zero, and
ignores your change. Try setting tcp_time_wait_interval to 6.
You might find the following "Solaris - Tuning Your TCP/IP Stack"
document useful:
http://www.sean.de/Solaris/soltune.html
Alex.
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