The buffer class encapsulates the movement of raw C arrays between
host and devices.
The `Buffer` class itself is not associated with any device. Instead,
`Buffer` is used in conjunction with a new templated class named
`DeviceAdapterMemoryManager` that can allocate data on a given
device and transfer data as necessary. `DeviceAdapterMemoryManager`
will eventually replace the more complicated device adapter classes
that manage data on a device.
The code in `DeviceAdapterMemoryManager` is actually enclosed in
virtual methods. This allows us to limit the number of classes that
need to be compiled for a device. Rather, the implementation of
`DeviceAdapterMemoryManager` is compiled once with whatever compiler
is necessary, and then the `RuntimeDeviceInformation` is used to
get the correct object instance.
The RuntimeDeviceTracker had grown organically to handle multiple
different roles inside VTK-m. Now that we have device tags
that can be passed around at runtime, large portions of
the RuntimeDeviceTracker API aren't needed.
Additionally the RuntimeDeviceTracker had a dependency on knowing
the names of each device, and this wasn't possible
as that information was part of its self. Now we have moved that
information into RuntimeDeviceInformation and have broken
the recursion.
By making RuntimeDeviceInformation class template independent, vtkm is
able to detect
device info at runtime with a runtime specified deviceId. In the past
it's impossible
because the CRTP pattern does not allow function overloading(compiler
would complain
that DeviceAdapterRuntimeDetector does not have Exists() function
defined).
The previous implementation of DeviceAdapterRuntimeDetector caused
multiple differing definitions of the same class to exist and
was causing the runtime device tracker to report CUDA as disabled
when it actually was enabled.
The ODR was caused by having a default implementation for
DeviceAdapterRuntimeDetector and a specific specialization for
CUDA. If a library had both CUDA and C++ sources it would pick up
both implementations and would have undefined behavior. In general
it would think the CUDA backend was disabled.
To avoid this kind of situation in the future I have reworked VTK-m
so that each device adapter must implement DeviceAdapterRuntimeDetector
for that device.
Sandia National Laboratories recently changed management from the
Sandia Corporation to the National Technology & Engineering Solutions
of Sandia, LLC (NTESS). The copyright statements need to be updated
accordingly.
Change the VTKM_CONT_EXPORT to VTKM_CONT. (Likewise for EXEC and
EXEC_CONT.) Remove the inline from these macros so that they can be
applied to everything, including implementations in a library.
Because inline is not declared in these modifies, you have to add the
keyword to functions and methods where the implementation is not inlined
in the class.
The RuntimeDeviceInformation class allows developers to check if a given
device is supported on a machine at runtime. This allows developers to properly
check for CUDA support before running any worklets.
