[petsc-dev] sm_70

[Barry Smith]

> On Sep 25, 2020, at 8:36 PM, Jacob Faibussowitsch <jacob.fai at gmail.com> wrote:
> 
>>  Configure by default should find out the available GPU and build for that sm_*  it should not require the user to set this (how the heck is the user going to know what to set?)  If I remember correctly there is a utility available that gives this information. 
> For CUDA I believe the tool is nvidia-smi. Should make sure this automatic detection works when configuring —with-batch though since login nodes might have different arch than compute.

  Would someone buying a machine be that perverse, they put a different GPU on the front end than the back end? Sadly, yes, your point is good, somehow on batch systems one wants the backend GPU information.

  Maybe on Cray systems it is hidden in one of the six million environmental variables they set. 

  Barry

> 
> Best regards,
> 
> Jacob Faibussowitsch
> (Jacob Fai - booss - oh - vitch)
> Cell: (312) 694-3391
> 
>> On Sep 25, 2020, at 21:09, Barry Smith <bsmith at petsc.dev <mailto:bsmith at petsc.dev>> wrote:
>> 
>> 
>>   Configure by default should find out the available GPU and build for that sm_*  it should not require the user to set this (how the heck is the user going to know what to set?)  If I remember correctly there is a utility available that gives this information. 
>> 
>>   For generic builds like in package distributions I don't know how it should work, ideally all the possibilities would be available in the library and at run time the correct one will be utilized. 
>> 
>>   Barry
>> 
>> 
>>> On Sep 25, 2020, at 5:49 PM, Mark Adams <mfadams at lbl.gov <mailto:mfadams at lbl.gov>> wrote:
>>> 
>>>    '--CUDAFLAGS=-arch=sm_70',
>>> 
>>> seems to fix this.
>>> 
>>> On Fri, Sep 25, 2020 at 6:31 PM Mark Adams <mfadams at lbl.gov <mailto:mfadams at lbl.gov>> wrote:
>>> I see kokkos and hyper have a sm_70 flag, but I don't see one for PETSc.
>>> 
>>> It looks like you have to specify this to get modern atomics to work in Cuda. I get:
>>> 
>>> /ccs/home/adams/petsc/include/petscaijdevice.h(99): error: no instance of overloaded function "atomicAdd" matches the argument list
>>>             argument types are: (double *, double)
>>> 
>>> I tried using a Kokkos configuration, thinking I could get these sm_70 flags, but that did not work.
>>> 
>>> Any ideas?
>>> 
>>> Mark
>> 
> 

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