[Beowulf] Performance characterising a HPC application
greg.lindahl at qlogic.com
Mon Mar 26 09:57:51 PDT 2007
On Mon, Mar 26, 2007 at 09:38:43AM -0700, Gilad Shainer wrote:
> This is yet another example of "fair" comparison. Unlike Qlogic,
> Mellanox offer a family of products for PCIe servers, and there are
> multiple MPI versions that support those products. The performance
> depends on the hardware you pick and the software you use.
There are 4 MPIs that support InfiniPath's InfiniBand extension. The
servers basically were identical in this comparison: 3 Ghz dual/dual
If you'd like to suggest a better MPI to HP, please do so.
> Why don't you look at
You didn't say where you got the InfiniPath Fluent numbers. If it's my
whitepaper, I was not running version 6.3 of Fluent. Also, my number
was not run with HP-MPI. But in another month, I'll have a new whitepaper
with a Fluent chart, run with 6.3 and HP-MPI.
> This shows that Mellanox SDR beats Qlogic, even on a latency sensitive
> applications, and that was before ConnectX.
Fluent isn't latency sensitive at the L problem size. Real customer
runs with Fluent are much larger than the L problem size. (I just
spent a few days visiting with a Formula 1 racing team, so this is
fresh in my mind.)
> As for the overhead portion, this paper does not compare hardware to
> hardware overhead, and it is greatly influenced by the MPI software
If you'd like to suggest to Doug how your number could be improved,
please do so. You've had since September 2005.
> But who cares what exactly did they measured, right?..... Anyway, it
> is very reasonable to believe that On-loading architecture has lower
> CPU overhead than Off-loading one...
You're correct, "everybody knows" that onload must have higher
overhead. Why bother testing it? "Everybody knows" that the cpu with
the highest Ghz is fastest.
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