From rossini@u.washington.edu  Tue Aug 20 20:53:09 2002
From: rossini@u.washington.edu (A.J. Rossini)
Date: 20 Aug 2002 12:53:09 -0700
Subject: question about Rpvm, SNOW, etc.
In-Reply-To: <m2adnhnx9t.fsf@qiuranke.phony.washington.edu>
References: <51F9C42DA15CD311BD220008C707D81906FFC5AD@usrymx10.merck.com>
 <m2adnhnx9t.fsf@qiuranke.phony.washington.edu>
Message-ID: <87y9b1b93u.fsf@jeeves.blindglobe.net>

>>>>> "michael" == Michael Na Li <lina@u.washington.edu> writes:

    michael> I got similar timing with our cluster.  Saving and loading the object to/from
    michael> a file require about 1.5 seconds each, which I assume is the cost of the
    michael> serialization (plus file reading and writing).  Then it seems the packing (as
    michael> bytes), transferring, and unpacking the object take 7-8 seconds??

    michael> I wonder how much the serialization itself hurts the performance.  Would
    michael> sending raw numbers with pvm routines improve the performance?

It might.  It is "well-known" that PVM (and MPI, and other
message-passing systems) have a marshalling overhead that can be
easily beat by RPC or direct socket programming.  This suggests that
the lower/rawer the data at the message passing stage, the faster it
might be.  

best,
-tony

-- 
A.J. Rossini				Rsrch. Asst. Prof. of Biostatistics
U. of Washington Biostatistics		rossini@u.washington.edu	
FHCRC/SCHARP/HIV Vaccine Trials Net	rossini@scharp.org
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question about Rpvm, SNOW, etc.
A.J. Rossini