Newsgroups: comp.parallel.pvm
From: Chetan N Vora <chet@brc.uconn.edu>
Subject: How many tasks can one spawn on a single host
Organization: University of Connecticut
Date: 15 Nov 1995 21:58:55 GMT
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Message-ID: <48dnqv$15m@orson.eng2.uconn.edu>

Hi everyone,

I am trying to build a parallel MD code using the master-slave paradigm.
Currently, I am using two Sparcstation 2000 with 8 cpus each connected with
Ethernet. I am having the following problems.

Problem 1: My code runs fine when I run it on a single host and spawn less than
6 slaves processes.But it gives me the libpvm error -
"libpvm [task number]: peer_conn() shmat to t40006: Too many open files" 
when I spawn more than 5 tasks.

What does this message mean ?? I get this error only when the no. of slaves
exceed 5 ; the program does go to completion but doesn't give correct results
(because of incomplete computations, I guess.) Is there any heuristic metric
about how many tasks should one spawn on a host ??

Problem 2: When I add the other host to the configuration and try to spawn
tasks using PvmTaskDefault, the code just hangs. 

Symptoms:
The log file on host on which I started the console shows the tasks to be
spawned with some task(s) having the error
"libpvm[task number]: mroute() frag with no message".

It appears that this task(s) doesn't receive at all the stuff that the master
sends it.

Is there any documentation about the meaning of the error messages that are
returned in the log file ??

Any help will be great appreciated.

Thanks in advance,
Chet

 
-- 
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Chetan 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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