Xeon (2.4GHz) x 2
cpu/pe 　walltime
192 　 　　264　（72）

Xeon (2.4GHz) x 4
cpu/pe　　walltime
113 　　　 190　　(77)

Pen 4 (3.0GHz) x 2
cpu/pe　 walltime
148 　　　184　 （36）

Timing measurments by DFT Molecular Dynamics code
(ab initio molecular dynamics code)

● 181 (C,N,H) atoms, 60x60x192 grids, 2 SCF iterations

●　Red Hat Linux 7.3, Portland Fortran/C compilers 5.1,
　　Scalapack package (self compiled)

● Xeon 2.4 GHz - smp (dual)/533MHz FSB, chipset intel E7505
　　PC2100 512MBx2, Hyper-threading is off

● Pentium 4 3.0GHz/800MHz FSB, chipset intel 875P
　　PC3200 512MBx2

● Communications via Gigabit network
　　a) on board NIC,　b) on board bcm5700, 　c) 3Com996

Oct.1, 2003/May 10, 2004

　Computation with two Pentium 4 machines is faster than with a 4-Xeon (dual cpu)
cluster, which is possibly due to the single NIC for dual cpus or memory band-width limitation of the Xeon architecture.Performance of the Pentium 4 cluster is excellent
for the ab initio molecular dynamics code, except for the communication overhead.
　 Interestingly, the computation per processor with the Pentium 4 is even faster
than that with the Xeon cpus in terms of the processor's clock speed ratio.

　Recently, a significant speedup has been achieved by introduction of the GAMMA
communication software (Genoa Active Message Machine; thanks to Dr.G.Ciaccio
(Genoa University); http://www.disi.unige.it/project/gamma/) onto the Pentium 4 cluster.
A gigabit ethernet with 3Com996 network interface cards is used. Communication overhead has almost been eliminated due to this non TCP/IP method. This result is
close to the performance of the RISC machine IBM Power 4 "Regatta" (1.5GHz).

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Pen 4 (3.0GHz) x 4
cpu/pe 　walltime
79　　　　 129 　（56）

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Pen 4 (3.0GHz) x 6
cpu/pe 　walltime
5１ 　　　　96　　（45）.

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MPI/GAMMA
cpu/pe　 walltime
66　　　　 66　 （0.1）

TCP/IP
cpu/pe　 walltime
67　　　　 93　 （26）

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