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From Tim Broberg <Tim.Brob...@exar.com>
Subject RE: Matrix multiplication in Hadoop
Date Sat, 19 Nov 2011 16:34:54 GMT
Perhaps this is a good candidate for a native library, then?

________________________________________
From: Mike Davis [xmikedavis@gmail.com]
Sent: Friday, November 18, 2011 7:39 PM
To: common-user@hadoop.apache.org
Subject: Re: Matrix multiplication in Hadoop

On Friday, November 18, 2011, Mike Spreitzer <mspreitz@us.ibm.com> wrote:
>  Why is matrix multiplication ill-suited for Hadoop?

IMHO, a huge issue here is the JVM's inability to fully support cpu vendor
specific SIMD instructions and, by extension, optimized BLAS routines.
Running a large MM task using intel's MKL rather than relying on generic
compiler optimization is orders of magnitude faster on a single multicore
processor. I see almost no way that Hadoop could win such a CPU intensive
task against an mpi cluster with even a tenth of the nodes running with a
decently tuned BLAS library. Racing even against a single CPU might be
difficult, given the i/o overhead.

Still, it's a reasonably common problem and we shouldn't murder the good in
favor of the best. I'm certain a MM/LinAlg Hadoop library with even
mediocre performance, wrt C, would get used.

--
Mike Davis

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