Newsgroups: comp.parallel.pvm
From: Chet Vora <chet@brc.uconn.edu>
Subject: Re: perf diff b/w spawing on single vs many machines
Organization: University of Connecticut
Date: 6 Mar 1996 21:09:44 GMT
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Message-ID: <4hkuuo$kof@orson.eng2.uconn.edu>

Saghir Ahmed Shaikh <shaikh@ece.utexas.edu> wrote:

>
>It turned out  to be that if I spawn same no. of process on one
>workstations, it is faster as compared to if i spawn the same no. of
>processes in let's say 4-5 workstations. Now I wonder that is it beacuse
>
>(i) data format changes
>(ii) Or pvm deamon knows it that I have to sent a message to the same
>machine so it takes less no. of time? 
>
>
>Please suggest what is going on?
>
>thanks my email is saghir@mail.utexas.edu
>

A likely explanation:
PVM daemon uses the loopback interface if it sends any message to itself (which
 will be the case if it's going to spawn tasks on the same host as itself) thus 
 bypassing the packet layer completely. Consequently, less spawning cost than
 the other case.

-- 
*******************************************************************************
Chet Vora		www: http://www.eng2.uconn.edu/~chet
The scientific theory I like the most is that Saturn's rings are composed 
entirely of lost airline baggage.  -Mark Russel
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