Workshop on Personal Computers based Networks Of Workstations
by M. Verma and T.-c. Chiueh,
Computer Science Department, SUNY at Stony Brook, USA.
Abstract
Pupa is a low-latency communication system that provides the same
quality of message delivery as TCP but is designed specifically
for a parallel computing cluster connected by a 100 Mbits/sec Fast Ethernet.
The implementation has been fully operational for over a year, and several
systems have been built on top of Pupa, including a compiler-directed
distributed shared virtual memory system, Locust, and a parallel
multimedia index server, PAMIS. To minimize buffer management
overhead, Pupa uses per-sender/per-receiver fixed-sized FIFO buffers
to optimize for the common case, rather than a shared variable-length
linked-list buffer pool. In addition, Pupa features a sender-controlled
acknowledgement and an optimistic flow control scheme to reduce
the overhead of providing reliable in-order message delivery.
Our performance results show that Pupa is more than twice as fast as
the fast path of TCP in terms of latency, and is about 1.5 times better
in terms of throughput. This paper presents the design decisions during
the development of Pupa, the results of a detailed performance
study of the Pupa prototype, as well as the implementation experiences
from Pupa-based applications development.
by G. Ciaccio,
DISI, University of Genoa, Italy.
Abstract
The current prototype of the Genoa Active Message MAchine (GAMMA) is a
low-overhead, Active Messages-based inter-process communication layer
implemented mainly at kernel level in the Linux Operating System.
It runs on a pool of low-cost Pentium-based Personal Computers (PCs)
networked by a low-cost 100base-TX Ethernet hub to form a low-cost
message-passing parallel platform. In this paper we describe in detail
how GAMMA could achieve unprecedented communication performance (less
than 13 microsec. one-way user-to-user latency time and up to 98% of the
communication throughput of the raw interconnection hardware) on such
a kind of low-cost parallel architecture.
by L. Prylli and
B. Tourancheau,
LIIPC & INRIA ReMaP, LIP, ENS-Lyon, France.
Abstract
High speed networks are now providing incredible performances. Software
evolution is slow and the old protocol stacks are no longer adequate for
these kind of communication speed. When bandwidth increases the latency
should decrease as much in order to keep the system balance. With the
current network technology the main bottleneck is most of the time the
software that makes the interface between the hardware and the user.
We designed and implemented new protocols of transmission targeted first
to parallel computing that squeeze the most out of the high speed
Myrinet network without wasting time in system calls or memory copies,
giving all the speed to the applications.
This design is presented here as well as experimental results that lead
to achieve real Gigabit/s throughput and less than 5 microsec latency
on a cluster of PC workstations with this "cheap" network hardware.
Moreover, our networking results compare favorably with the expensive
parallel computers or ATM LANs.
by Y.Tanaka, M.Matsuda, M.Ando,
K.Kubota, and M.Sato,
Massively Parallel Perf. Lab., Real World Computing Partnership, Japan.
Abstract
We have built COMPaS, a cluster of SMPs, which consists of eight
quad-processor Pentium Pro. We designed and implemented a remote
memory based user-level communication layer which provides
low-overhead and high-bandwidth using Myrinet.
To take advantage of the locality in each SMP node, we integrated
multi-threaded programming with Solaris threads for intra-nodes and
message passing/remote memory operations based programming for
inter-nodes.
In this paper, we reported the basic performance of COMPaS, design,
implementation, and the performance of our communication primitives, a
hybrid shared memory/distributed memory programming on COMPaS and its
preliminary evaluation, and the performance characteristics of COMPaS.
by J.M. Blum, T.M. Warschko, and W.F. Tichy,
Dept. of Informatics, University of Karlsruhe, Germany
Abstract
PULC is a user-level communication library for workstation clusters. PULC
provide a multi-user, multi-programming communication library for user
level communication on top of high-speed communication hardware. In this
paper, we describe the design of the communication subsystem, a first
implementation on top of the ParaStation communication card, and benchmark
results of this first implementation.
PULC removes the operating system from the communication path
and offers a multi-process environment with user-space communication.
Additionally, we have moved some operating system functionality to the user
level to provide higher efficiency and flexibility. Message demultiplexing,
protocol processing, hardware interfacing, and mutual exclusion of
critical sections are all implemented in user-level. PULC offers the programmer
multiple interfaces including TCP user-level sockets, MPI, PVM, and
Active Messages. Throughput and latency are close to the hardware
performance (e.g., the TCP socket protocol has a latency of less than
9 us).
by S.J. Ryan and
H. Bryhni,
Dept. of Informatics, University of Oslo, Norway.
Abstract
We show how the traditional protocol stack, such as TCP/IP, can be
eliminated for socket based high speed communication within a cluster.
The SCI shared memory interconnect is used as an example, and we
demonstrate how existing applications can utilize the new technology
without relinking. This is done by dynamically remapping the TCP/IP
socket implementation to our high performance SCILAN sockets.
We describe a novel mechanism for synchronization of communication
through shared memory, aimed at minimizing the interrupt load on the
receiving system. We discuss the implementation and present an
evaluation with comparison to alternative technologies, such as 100baseT
and ATM. Significant improvement over current solutions are shown both
in terms of throughput and latency.
by G. Ciaccio and
V. Di Martino,
CASPUR c/o Universita' "La Sapienza", Roma, Italy.
Abstract
GAMMA is the abbreviation of Genoa Active Message Machine, a low cost cluster
of Personal Computers (PCs) with commodity (100base-T Ethernet) network
hardware and a enhanced Linux operating system to obtain low latency on
message exchange based on the Active Message paradigm. The target of our
work is the porting on GAMMA of a communication intensive Molecular Dynamics
code used to study polarizable fluids. First of all the GAMMA library
routines has been extended to permit calls from Fortran code. The second
steps has been the modification of the communication policy in the original
PVM code to fit in the hardware and software communication layer. The
third step, still in progress, is the benchmarking and the performance
comparison among GAMMA, a 100base-T Ethernet LAN of PC running PVM, and a
cluster of SMP computers with proprietary network solutions. In this
paper we will discuss the difficulties and the adopted solutions to port
the application on GAMMA while preserving the original speedups and
overall performance obtained on vendor NOWs of higher class of costs.
by M. Baker and G. Fox,
CSM, University of Portsmouth, UK
Abstract
The aim of this paper is to discuss the functionality and performance of the
current generation of MPI environments that are available for NT. The three
environments investigated are WinMPICH from the Engineering Research Center
at Mississippi State University, WMPI from the Instituto Superior de
Engenharia de Coimbra, Portugal and FM-MPI from the Dept. of Computer
Science at the University of Illinois at Urbana-Champaign.
In the first part of the paper we discuss briefly the advantages of using
clusters of workstations and then move on to describe NT and the MPI
environments being investigated. In the second part of the paper we
describe, and then report on our experiences of assessing the functionality
of the MPI environments. In the third part of the paper we make a preliminary
evaluation of the performance characteristics of the environments assesses
using the ParkBench benchmark suite. Finally, we summarise our findings
and suggest a number of improvement that could be made to the environments
assessed.
chiola@disi.unige.it, Jan. 19, 1998