Dear all,

is there a chance that, for matrices smaller than a certain size, MAGMA decides to NOT use the GPU at all and reverts to the CPU lapack implementation (e.g. openblas)?

Thanks in advance,

Paolo

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Dear all,

is there a chance that, for matrices smaller than a certain size, MAGMA decides to NOT use the GPU at all and reverts to the CPU lapack implementation (e.g. openblas)?

Thanks in advance,

Paolo

is there a chance that, for matrices smaller than a certain size, MAGMA decides to NOT use the GPU at all and reverts to the CPU lapack implementation (e.g. openblas)?

Thanks in advance,

Paolo

- paoloviviani
**Posts:**14**Joined:**Mon Nov 09, 2015 12:17 pm

I'm asking this since I'm comparing Openblas ssyevd against Magma ssyevd and I see that, at least until the matrix size is 128x128, the timing are exactly the same, while for bigger matrices the behavior changes.

- paoloviviani
**Posts:**14**Joined:**Mon Nov 09, 2015 12:17 pm

Yes, small matrices are simply handed to LAPACK. There is not enough work for the GPU to be efficient and overcome the cost of copying the matrix to the GPU.

-mark

-mark

- mgates3
**Posts:**791**Joined:**Fri Jan 06, 2012 2:13 pm

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