[Spread-users] Spread performance

John Schultz jschultz at spreadconcepts.com
Tue May 25 15:01:45 EDT 2004

Pau Artigas wrote:

> 	Is this the expected performance/behaviour?

The behavior you describe is expected in Spread 3.  When a daemon sends 
a message it sends it "locally" through UDP broadcast and directly to 
the representative (the first listed daemon in the segment that is 
participating in that daemon membership) of each of the other segments. 
  No traffic pruning is done based on whether or not the different 
segments have users in a group or not.  You probably could develop a 
method that would do this pruning but Spread currently does not.

Also, after sending traffic, the control token of the daemons continues 
to circulate around the ring for a bit (by default I believe) -- the 
expectation being that there exists a "locality of reference" of 
traffic: once some traffic is sent it is highly likely that more traffic 
will follow soon after; conversly when no traffic has been sent for a 
while it is likely that the system will remain dormant for a period of 
time, so the token should stop circulating.

It is hard for me to say if the performance you got is expected or not, 
especially since you didn't tell us what it was :) To make a guess at 
that we'd have to know what the network links between the different 
sites looks like in terms of latency/throughput/loss rate.  In the past, 
I believe (correct me if I'm wrong CNDS) that with Spread 3 we have 
pushed approx. 1-3 Mbit/s in a wide area configuration with several 
sites stretching across the USA.

> 	Is the spread.conf ok?

Looks ok to me as long as you are actually using different IP addresses 
for the multicast/broadcast address and the machine addresses in your 
config file.

> 	Does spread need a warmup to create optimum distribution routes?

Spread 3 does not use any optimized distribution routes.  It uses the 
simple heurstic I stated above and a token ring for passing a control 
token.  It does take some time to establish daemon memberships (the 
token ring) before client communications are sent.

> 	I'm doing something wrong?

Not that I can tell.

John Lane Schultz
Spread Concepts LLC
Phn: 443 838 2200

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