At 21:01 30.01.2008, Mark Hahn <[EMAIL PROTECTED]> wrote:
whenever I ask about IB bandwidth, people always point fingers
at weather codes, which apparently are fond of doing the transpose
in multi-dimension FFT's using all-to-all. while convenient, this
seems a bit silly, since transpose is O(N) communications, not O(N^2).
Mark,
interconnect does matter. Here is a solid benchmark using WRF, 128
cores, Woodcrest 3.00GHz. System spec can be found at
http://www.spec.org/mpi2007/results/res2007q4/mpi2007-20071013-00029.html
Scali MPI Connect 5.6.2 using IB (IB as specified in the link above):
Success 127.wrf2 base mref ratio 21.03, runtime 370.653066
Scali MPI Connect 5.6.2 using Gbe (Broadcom NetXtreme II BCM5708
1000Base-T (B2), Broadcom NetXtreme II Gigabit Ethernet Driver bnx2
v1.3.29, 9k MTU, Switch? Jeff, can you fill in here, the system
should be familiar to you):
Success 127.wrf2 base mref ratio=4.82, runtime=1618.248048
That's a pretty decent advantage to IB, isn't?
Thanks, Hakon
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