http:^^www.cs.cornell.edu^info^projects^cam^

This data set contains WWW-pages collected from computer science departments of various universities

The Generic Active Message Specification, Version 1.1 defines an Active
Messages interface which is portable across a variety of parallel machines.
Implementations are available for the
<!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><A HREF="http://www.cs.cornell.edu/Info/Projects/U-Net/">U-Net ATM cluster</A>,
the
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the
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the
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and the
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SP-2</a>.

<p>
<li><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><A HREF="http://www.cs.cornell.edu/Info/Projects/CAM/hoti-94.html"><b>Low-Latency Communication over ATM Networks
using Active Messages.</b></A><br>
Thorsten von Eicken, Veena Avula, Anyndia Basu, Vineet Buch,
<I>Presented at Hot Interconnects II</I>,
Aug 1994, Palo Alto, CA.
An abridged version of this paper appears in IEEE Micro Magazine, Feb. 1995.
<!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><A HREF="http://www.cs.cornell.edu/Info/Projects/CAM/hoti-94.ps"><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><img align=top src="http://www.cs.cornell.edu/Info/Projects/CAM/icon-ps.gif"></A>
<br>
<b>Slides</b> from Hot Interconnect talk.<!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><A HREF="http://www.cs.cornell.edu/Info/Projects/CAM/hoti-talk-94.ps"><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><img
align=top src="http://www.cs.cornell.edu/Info/Projects/CAM/icon-ps.gif"></A>
<br>
<b>Abstract:</b>
<br>
Recent developments in communication architectures for
parallel machines have made significant progress and reduced the
communication overheads and latencies by over an order of magnitude as
compared to earlier proposals. This paper examines whether these
techniques can carry over to clusters of workstations connected by an
ATM network even though clusters use standard operating system
software, are equipped with network interfaces optimized for stream
communication, do not allow direct protected user-level access to the
network, and use networks without reliable transmission or flow
control.
<br>
In a first part, this paper describes the differences in
communication characteristics between clusters of workstations built
from standard hardware and software components and state-of-the-art
multiprocessors. The lack of flow control and of operating system
coordination affects the communication layer design significantly and
requires larger buffers at each end than on multiprocessors. A second
part evaluates a prototype implementation of the low-latency Active
Messages communication model on a Sun workstation cluster
interconnected by an ATM network. Measurements show
application-to-application latencies of about 20 microseconds for small
messages which is roughly comparable to the Active Messages
implementation on the Thinking Machines CM-5 multiprocessor.

<p>
<li><b>Active Messages: a Mechanism for Integrated Communication and
Computation.</b>
von Eicken, T., D. E. Culler, S. C. Goldstein, and K. E. Schauser,
<I>Proceedings of the 19th Int'l Symp. on Computer Architecture</I>,
May 1992, Gold Coast, Australia.
<!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><A HREF="http://www.cs.cornell.edu/Info/Projects/CAM/isca92.ps"><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><img align=top src="http://www.cs.cornell.edu/Info/Projects/CAM/icon-ps.gif"></A>
<br>
<b>Abstract</b>
<br>
The design challenge for large-scale multiprocessors is (1) to
minimize communication overhead, (2) allow communication to overlap
computation, and (3) coordinate the two without sacrificing
processor cost/performance.  We show that existing message passing
multiprocessors have unnecessarily high communication costs.  Research
prototypes of message driven machines demonstrate low communication
overhead, but poor processor cost/performance.  We introduce a simple
communication mechanism, <i>Active Messages</i>, show that it is
intrinsic to both architectures, allows cost effective use of the
hardware, and offers tremendous flexibility.  Implementations on nCUBE/2
And CM-5 are described and evaluated using a split-phase shared-memory
extension to C, <i>Split-C</i>.  We further show that active messages
are sufficient to implement the dynamically scheduled languages for
which message driven machines were designed.  With this mechanism,
latency tolerance becomes a programming/compiling concern.  Hardware
support for active messages is desirable and we outline a range of
enhancements to mainstream processors.

<p>
<li><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><A HREF="http://www.cs.cornell.edu/Info/People/tve/thesis/"><b>Active Messages: an Efficient
Communication Architecture for Multiprocessors.</b></a> von Eicken, T.,
Ph.D. Thesis, November 1993, University of California at Berkeley.
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</ul>

<H2>Projects at other sites</H2>
<ul>
<li><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><a href="http://now.cs.berkeley.edu/active_messages.html">Active Messages
in the Berkeley NoW project</a>
</ul>

<hr>
For further information contact
<!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><A HREF="mailto:[e-mail]">Thorsten von Eicken</A>

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