[Spread-users] sublinear movement

Piotr Kozieradzki piotoru at zodiac.mimuw.edu.pl
Thu Feb 5 03:49:52 EST 2004

Jonathan Stanton wrote:

>The token will continue to rotate while waiting for new 
>messages to be generated. To prevent too much wasted bandwith with tokens 
>doing now work, Spread stops rotating the token after 100 rotations that 
>accomplish nothing and then switches to only sending the token if a daemon 
>asks for it, or once a second or so. So the extra 45 tokens were valid 
>tokens, but no real messages were sent during their cycle (the tokens do 
>not carry any message content themselves). 
>We are actually going to switch this in the next version so the token goes
>in to 'idle' mode faster as people are often surprised that the token
>rotates even when no messages are being sent.
>I'm not sure about the exact packet counts you provide, but there is 
>definitly some fixed overhead per spread message, and some extra traffic 
>"per second" that will become less noticable the more messages you are 
>sending per second.
I my aplication I use 6 spread groups (now it is only 2 clients in each 
group one publisher one subscriber).

            A, B, C - 3 aplications one per each host
            p -    publisher
            s - subscriber

A p1    --> B s1
A p2    --> C s1

B p1    --> A s2
B p2    --> C s2

C p1    --> A s1
C p2    --> B s2

each publisher sends 30 packet/ s (each packet 250B).  each aplication 
(A,B and C) includes 2 publisher and 2 subscriber (A includes Ap1, Ap2, 
As1 and As2 ;  B include Bp1, Bp2, ... etc). So each genarate proces (A, 
B and C) generate 30 * 2 * 250 B/s = 15000B/s.
But in fact the trafic was about 160kB OUT and ~200kB IN.
But after that I test it with 300 packet /s (each publisher).
I found something strange: on host with proces A trafic was something 
about ~170kB - ~200kB  OUT    and ~400kB. Isn't to much?

After about one client (A xor B xor C) fall dawn with -8 error.

>On Wed, Feb 04, 2004 at 12:42:29PM +0100, Piotr Kozieradzki wrote:
>>I test spread on 3 host (Linux debian, CPU: Pentium II, network 100Mb) 
>>in one segment (LAN, ethernet)
>>On each  host is one spread demon and one spread client . Each client 
>>has 2 publisher  and two subscriber. So each program sends his messeges 
>>to  other program (one publisher from host A sends messeges to 
>>subscriber from B and one to subscriber from C, etc. )
>>In first test I send 30 packet per second (200B each packet) from each 
>>publisher.  But avarage trafific is about 160B / s (it is about 10 times 
>>more than it shuold be).
>>After that I change my program so each generate 300  pac sekond (200B 
>>each packet) from each publisher , it generate trafic about 290B/s. Is 
>>it correct?
>>The other test was I run One demon on host A and one client (spuser) on 
>>the same host. ther was no other spread demon in network. On spuser  i 
>>create group MY_GROUP and send to this group one message "Hello". I saw 
>>about 45 annoucment from spread demon "Received token". Does it meen 
>>that he received 45 packet?
>>Piotr Kozieradzki
>>Spread-users mailing list
>>Spread-users at lists.spread.org

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