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Beginner
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multithreaded performance of sparse blas not good

Hi all

I'm having trouble with matrix multiplication on Sparse Blas. I am trying to multiply 2 huge matrices and compare multithreaded and single threaded performance on an quad core AMD Phenom II 940 with 4GB of DDR3 RAM.

I am using mkl_scsrmm. On benchmark, I repeat the call to mkl_scsrmm a hundred times and I compute the total time in seconds. The matrices have 700,000 (dense) and 20,000 (sparse) elements.

The problem is that the multithreaded performance is only 5% better than single threaded sequential performance.

What is happening?

Ashade

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Black Belt
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With such benchmarks, the devil is in the details. You may be interested to see what Amdahl's Law states regarding your runs.

If you want more specific help, you will have to document what you did, and state reasons why the results are not what was expected.
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Moderator
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Ashade,
Do you mean that you see 5% of scalability with 4 cores vs 1 core?
what is the matrixes size?
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