
\section{Measurements}
In this section we cite and briefly discuss performance numbers from a
second prototype implementation of SuperWeb, called Javelin
~\cite{javelin}.  For a more detailed presentation of the design issues,
the performance results and the application used the reader is referred to
~\cite{javelin}.  The experiments were conducted on a heterogeneous
network of computers consisting of a 64-node Meiko CS-2, Sun
UltraSparcs, and Pentium PCs connected by an SCI and 10 Mbit Ethernet
networks.  The tests were done with the Mersenne prime application.
This application tests whether or not a large number is a Mersenne
prime, i.e., a prime of the form $2^p-1$.  This is a very coarse
grained application and thus is well suited for executing on the
SuperWeb architecture.

The Netscape Navigator browser was used on all platforms except
the Pentium PCs. The Pentium PCs were running the Windows 95 version of 
Microsoft Internet Explorer which has a just-in-time compiler.

The first set of measurements were performed on clusters of identical
machines. This test shows that one can obtain good speedup for the
Mersenne Prime Application. Figure~\ref{fig:speedup} presents the
speedup curves for test runs on a 64-node Meiko CS-2.
% \footnote{The nodes on
%  a CS-2 are Sparc 10 processors running an enhanced version of Solaris.}
%
% (left) and for a cluster of 8 Sun UltraSparcs running at 143 MHz and 167 MHz
% (right). In both cases,
% the speedup was close to linear as long as the ratio of job size to number of
% processors was big enough.

\begin{figure}[htbp]
\centerline{\psfig{figure=MeikoSpeedup.eps,width=3.2in,clip=}}
\caption{\em {Speedup curves for the Mersenne primality test of all prime
exponents less than 3000. Tests were run on a 64-node Meiko CS-2
(Sparc 10 processors running Solaris${\ }$2.3).}}
\label{fig:speedup}
\end{figure}

The second test was on a heterogeneous environment
consisting of 2 PCs running Windows 95, 8 UltraSparcs and 32 Meiko
nodes (Figure~\ref{fig:hetero}).
The main purpose of this test was to show that
the Javelin prototype is capable of running parallel tasks on a variety of
computing platforms. This reflects a possible real situation of
computing resources registered at a broker at some moment.
Figure~\ref{fig:hetero} also shows the importance of advanced
compilation techniques. Note that the two 166MHz PCs using
a just-in-time Java compiler perform just as fast as the 32 nodes
of the Meiko CS-2 running at 40MHz using the Netscape Java interpreter.
Combining the resources of all machines resulted in an
improvement, albeit not a substantial one, due to the big
difference in speed between the compiled and interpreted versions.
\label{sec:Measurements}

\begin{figure}[htbp]
\centerline{\psfig{figure=Hetero.eps,width=3.4in,clip=}}
\caption{\em {Mersenne primality test of all prime
exponents less than 3000. Tests were run on a heterogeneous platform
consisting of Pentiums, Meiko CS-2 nodes (Sparc 10s) and UltraSparcs.}}
\label{fig:hetero}
\end{figure}








