Newsgroups: comp.parallel.pvm
From: papadopo@cs.utk.edu (Philip Papadopoulos)
Subject: Re: Asynchronous message passing
Organization: CS Department, University of Tennessee, Knoxville
Date: 6 Nov 1996 10:24:32 -0500
Message-ID: <55qajgINNi4m@duncan.cs.utk.edu>

In article <55krt9$isn@whitbeck.ncl.ac.uk> Jim Webber <james.webber@ncl.ac.uk> writes:
>Hi,
>
>Just a query about asyncronous messages in PVM. Is the mechanism for sending
>them implemented with some arbitrarily size queue?
Depends on the implementation, and the message route.
Maybe asynchronous is the wrong way to term what PVM does on send.
pvm_send (psend, mcast) will not return to the caller until the
send buffer is safe to re-use.  It does not wait until the receiver
has actually received the message. 

If sending on the default route, then messageswill get buffered by the
daemons until a the task is ready to receive messages.  BUffering is
limitd by the amount of memory (real+virtual) that you have on 
your machines. THere is no preset limit in PVM on the amount of
memory that it will chew up. In fact, a malicious programmer can
make a daemon or task swell an use all available memory.


>
>If so, is there a way of increasing the size of this queue as I'd like to send
>lots of quite long messages in a async fashion.


-Phil Papadopoulos

