[petsc-dev] No single precision support in ViennaCL?

Matthew Knepley knepley at gmail.com
Tue Jan 21 07:43:15 CST 2014

On Tue, Jan 21, 2014 at 3:15 AM, Karl Rupp <rupp at mcs.anl.gov> wrote:

> Hi,
> >     It looks like ViennaCL in petsc doesn't support single precision
>>     (which I need cause my (old) GPU doesn't support double precision).
>>     I get the following error:
>>     Cannot use viennacl withOUT double precision numbers, it is not
>>     coded for this capability
>>     Is there any way this can be enabled in the build?
>> This may be an oversight. Can you try adding
>>    self.double = 0
>> to the constructor in config/PETSc/packages/viennacl.py?
> Thanks, Matt. Do we want to provide some automatic marshalling to single
> precision if not provided by the device? For 'production use' it doesn't
> really matter, because GPUs today which offer only single precision are
> generally rather low-end and won't provide any substantial benefit over
> CPUs. However, it can be handy for debugging purposes. Any opinions?

I think we should since it also a way to decrease the PCI penalty.


> Best regards,
> Karli

What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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