From: Christian Wettergren <cwe@Csli.Stanford.EDU>
Date: Mon, 28 Aug 95 09:46:47 PDT
To: Piete Brooks <Piete.Brooks@cl.cam.ac.uk>
Subject: Re: Server congestion
In-Reply-To: <"swan.cl.cam.:027060:950828094002"@cl.cam.ac.uk>
Message-ID: <199508281645.JAA12868@Csli.Stanford.EDU>
MIME-Version: 1.0
Content-Type: text/plain



| > I talked about acks of acks in a previous message, and I guess is was
| > somewhat vague there.
| 
| ... and maybe based on a false premis ?
| 
| > What happened, according to my uninformed view, during the SSL2
| > challenge was that the server got congested, and had problems with
| > both answering to key allocation requests and ack replies.
| 
| Correct.
| 
| > I guess that the load of the machine was so high that it lost packets in 
the
| > input queues.
| 
| NO.
| 
| The load was very *LOW*.
| The problem was that the single threaded server was spending most of its ti
me
| talking to clients which failed to complete their interactions, and timed o
ut.
| The earlier client "ACK" code didn't hang around long enough, and gave up.
| Later code kept trying ....
| 
| > Client -----> UDP/Key allocation req ----> 
| 
| Nope -- basic fault here !! TCP not UDP !!

Ok, I'll be quiet now. It's funny when you think you know
what is happening based on an uninformed view, and simply
shuts out all the other pieces of info that gets to you.

By the way, thanks a lot Piete for the effort you put in!
You did excellent, and it was real fun! 32 hours with 
serious performance problems is simply amazing.

/Christian