[erlang-questions] how much time required to pass messages.

Vikrant <>
Tue Mar 31 06:40:08 CEST 2009


even if timer resolution is the reason why we don't see the change in time,
question remains same. why the change in time scales with M(number of
messages) and NOT with N (number of processes + number of messages)!

2009/3/29 Carsten Schultz <>

> Vikrant schrieb:
> >
> > 26> tokenring:tokenring(10000,1).
> > Time required to pass message 10000 times=3.00000 (4.40000) microsecond
> > .ok
> > 27> tokenring:tokenring(20000,1).
> > Time required to pass message 20000 times=3.00000 (4.65000) microsecond
> > .ok
> > 28> tokenring:tokenring(30000,1).
> > Time required to pass message 30000 times=3.33333 (4.63333) microsecond
> > .ok
> >
> > (time in bracket is system time and time outside bracket is user time in
> > microseconds.)
> >
> > This is surprising to me! I expected that time required to pass token
> > along N processes should be proportional to N!
>
> My guess here is that the resultion of the timer is 1/3.  So your
> results are 9, 9, 10.  Considering that these are rounded and that your
> function will have a constant term, these numbers are just to small to
> allow you to deduce much about your runtime function.  Change the second
> parameter into, say, 1000000 in all cases and see what happens.
>
> --
> Carsten Schultz (2:38, 33:47)
> http://carsten.codimi.de/
> PGP/GPG <http://carsten.codimi.de/%0APGP/GPG> key on the pgp.net key
> servers,
> fingerprint on my home page.
>
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