[petsc-dev] cuda failures of tests in master

[Barry Smith]

> On Aug 7, 2015, at 7:50 PM, Dominic Meiser <dmeiser at txcorp.com> wrote:
> 
> FYI I've opened a pull request that addresses this issue.
> 
> While going through the code I ran into a question regarding the semantics of VecPlaceArray and VecResetArray: Is the contents of the "unplaced" array supposed to be preserved so that the vector is completely restored upon calling VecResetArray? With the current implementation of VecPlaceArray_SeqCUSP and VecResetArray_SeqCUSP a situation can occur where the contents of the unplaced array gets clobbered. Does this need to be fixed?

   Hmm,  I think I always assumed the "unplaced" array was inaccessible during the time it is unplaced (since there is no public pointer to the array), this would mean that the values there shouldn't change. What are the exact details of how they can get changed?

   Thanks

   Barry

> 
> Cheers,
> Dominic
> 
> 
> On 08/07/2015 02:42 PM, Barry Smith wrote:
>> 
>>   Guardians of CUDA/GPUs
>> 
>> http://ftp.mcs.anl.gov/pub/petsc/nightlylogs/archive/2015/08/06/examples_master_arch-cuda-double_bb-proxy.log
>> http://ftp.mcs.anl.gov/pub/petsc/nightlylogs/archive/2015/08/06/examples_master_arch-cuda_bb-proxy.log
>> 
>> search for ex2_bjacobi
>> 
>> note that this example does not fail in non CUDA builds.
>> 
>> For some reason the iterative solver thinks it converges in 0 iterations but the answer is completely wrong.
>> 
>>   Barry
>> 
>> 
>> 
>> 
>> 
> 
> -- 
> Dominic Meiser
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