support for cuda_managed

[telegraphic]

On the wishlist: ability to use space='cuda_managed' in blocks. Currently it'll fail like this:

memory.cpp:252 Condition failed: "Valid bfMemcpy2D src space"
memory.cpp:252 error 10: BF_STATUS_INVALID_ARGUMENT

[jaycedowell]

This is sorta kinda tangentially related but I get various warnings related to managed memory when I compile under CUDA 10.1:

memory.cpp: In function ‘BFstatus bfGetSpace(const void*, BFspace*)’:
memory.cpp:62:23: warning: ‘cudaPointerAttributes::isManaged’ is deprecated 
   (declared at /usr/local/cuda/include/driver_types.h:1341) 
   [-Wdeprecated-declarations]
  } else if( ptr_attrs.isManaged ) {
                       ^
memory.cpp:62:23: warning: ‘cudaPointerAttributes::isManaged’ is deprecated 
   (declared at /usr/local/cuda/include/driver_types.h:1341) 
   [-Wdeprecated-declarations]
memory.cpp:65:21: warning: ‘cudaPointerAttributes::memoryType’ is 
   deprecated (declared at /usr/local/cuda/include/driver_types.h:1302) 
   [-Wdeprecated-declarations]
   switch( ptr_attrs.memoryType ) {
                     ^
memory.cpp:65:21: warning: ‘cudaPointerAttributes::memoryType’ is 
   deprecated (declared at /usr/local/cuda/include/driver_types.h:1302) 
   [-Wdeprecated-declarations]

This may become an issue in future CUDA releases.

[xsacha]

Just change it to switch(ptr_attrs.type) and (ptr_attrs.type == cudaMemoryTypeManaged)

[jaycedowell]

I started thinking about this again and my currently thinking is that it would be easy to support cuda_managed for Pascal and later. From what I can tell this should work seamlessly on those generations of GPUs and doesn't require the the explicit stream synchronization call of earlier generations.

[jaycedowell]

https://github.com/ledatelescope/bifrost/commit/90dfc3d32948d1c6628d58f70c2375d8578d2ee5 starts work on cuda_managed support for Pascal and later GPUs. I also added a test suite in https://github.com/ledatelescope/bifrost/commit/d0552ee589a81d06bc22f0de4d45b8761e0fe0ba but I have an intermittent failures on the "reduce" tests.

[jaycedowell]

Closing with the release of v0.10.0.