Experiences using your SDK with ViennaCL

Experiences using your SDK with ViennaCL

Hello,

just a brief introduction: I'm the head of the linear algebra library ViennaCL (see http://viennacl.sourceforge.net/ ). We are very happy to see that Intel is going for OpenCL as well, since this allows us to run our OpenCL kernels on Intel hardware efficiently.

We played a bit with the current version of the SDK and took some timings. To our surprise, the Intel backend turned out to be better than the "alpha"-status suggests.

Comparisons are carried out for the AMD APP SDK 2.3 on an up-to-date Funtoo-Linux, a rather recent NVIDIA driver (260.19.21) on Windows 7, and the Intel SDK on a Windows 7, all on the same machine. We couldn't get all three implementations to run under Windows 7, that's why the timings for the APP SDK using the CPU are from Linux. Thus, timings have to be taken with a grain of salt, but a general tendency can be seen.

Test 1: Kernel compilation times. The scalar, vector and matrix kernels are compiled in timings (in seconds) are taken:

AMD: 0.08 / 0.18 / 0.15
NVIDIA: 0.34 / 0.53 / 0.42
INTEL: 0.03 / 0.09 / 0.07

So, the kernel compilation seems to be pretty good on your implementation.

Test 2: OpenCL transfer overhead. A vector with 100.000 entries is set up. Then, each entry is read individually, so 100.000 OpenCL read requests have to be handled:

AMD: 21 us / entry
NVIDIA: 91 us / entry (including PCI-Express overhead w.r.t. GPU)
INTEL: 7.1 us / entry

Even though an overhead of 7.1us per entry is still orders of magnitude larger than just reading for example an STL-vector, we are happy to see that there is improvement on the OpenCL backend :-)

One more important issue: Since ViennaCL aims at high performance scientific computing, we wish to emphasize the scientific community's demand for a Linux version of the SDK.

If you require more feedback or benchmarks, feel free to contact us.

Best regards,
Karl Rupp

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For more complete information about compiler optimizations, see our Optimization Notice.

First, I would like to thank you for sharing this feedback
with us.

We are very pleased to see our product used with many different applications.

Ive explored your products web site and was impressed from the performance boost ViennaCL achieves on multicore machines as it is presented at: http://viennacl.sourceforge.net/viennacl-benchmarks.html.

I hope that with Intel OpenCL SDK support you may even able to improve the results.

We have seen the wide demand for Linux support with the SDK since we first released it and we hope to address your needs soon,

Regards,

-Arnon

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