David Miller wrote:
From: Ben Greear <[EMAIL PROTECTED]>
Date: Wed, 11 Apr 2007 13:26:36 -0700
Interestingly, I found this page mentioning a SACK problem in Linux:
http://www-didc.lbl.gov/TCP-tuning/linux.html
Don't read that page, it is the last place in the world your should
take hints and advice from, most of the problems they speak of there
have been fixed years ago.
Much of their memory and buffer settings are similar to what I've
seen elsewhere..and what I use, but it could be we're all getting
the same info from the same faulty source. Suggestions of a proper
site for tuning TCP for high speed/high latency links are welcome.
Please start instrumenting the TCP code instead of "poking around"
hoping you'll hit the grand jackpot by manipulating some sysctl
setting.
It doesn't help us and it won't help you, start reading and
understanding the TCP code, add debugging printk's, anything to get
more information about this.
And please don't report anything here until you have some solid piece
of debugging information, else I'll just sit here replying and
prodding you along ever so slowly. :(
Does the CWND == 1 count as solid? Any idea how/why this would go
to 1 in conjunction with the dup acks?
For the dup acks, I see nothing *but* dup acks on the wire...going in
both directions interestingly, at greater than 100,000 packets per second.
I don't mind adding printks...and I've started reading through the code,
but there is a lot of it, and indiscriminate printks will likely just
hide the problem because it will slow down performance so much.
Thanks,
Ben
--
Ben Greear <[EMAIL PROTECTED]>
Candela Technologies Inc http://www.candelatech.com
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