The `DeviceAdapter` provides an abstract interface to the accelerator
devices worklets and other algorithms run on. As such, the programmer has
less control about how the device launches each worklet. Each device
adapter has its own configuration parameters and other ways to attempt to
optimize how things are run, but these are always a universal set of
options that are applied to everything run on the device. There is no way
to specify launch parameters for a particular worklet.
To provide this information, VTK-m now supports `Hint`s to the device
adapter. The `DeviceAdapterAlgorithm::Schedule` method takes a templated
argument that is of the type `HintList`. This object contains a template
list of `Hint` types that provide suggestions on how to launch the parallel
execution. The device adapter will pick out hints that pertain to it and
adjust its launching accordingly.
These are called hints rather than, say, directives, because they don't
force the device adapter to do anything. The device adapter is free to
ignore any (and all) hints. The point is that the device adapter can take
into account the information to try to optimize for itself.
A provided hint can be tied to specific device adapters. In this way, an
worklet can further optimize itself. If multiple hints match a device
adapter, the last one in the list will be selected.
The `Worklet` base now has an internal type named `Hints` that points to a
`HintList` that is applied when the worklet is scheduled. Derived worklet
classes can provide hints by simply defining their own `Hints` type.
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.
Redesigns the TBB and Serial backends and the vtkm::exec::Task concept so that
we can re-use the same launching logic for all Worklets, instead of generating
per worlet code. To keep the performance the same the TilingTask now is past
a range of indices to work on, rather than a single index.
Binary size reduction:
WorkletTests_SERIAL old - 19MB
WorkletTests_SERIAL new - 18MB
WorkletTests_TBB old - 39MB
WorkletTests_TBB new - 18MB
libvtkAcceleratorsVTKm old - 48MB
libvtkAcceleratorsVTKm new - 19MB
Previously WorkletInvokeFunctor inherited from vtkm::exec::FunctorBase,
which is also the base class for all users Worklets and for all functors
based to DeviceAdapter::Schedule.
This is done for a few reasons. The first is that we reduce the
minimum size of user worklets. Previously the users worklet would hold
a reference to the error message, and so would the wrapper class added
when calling DeviceAdapter::Schedule. Now we only have the users worklet
holding a reference.
Second, by refactoring to have two base classes we can better improve
the documentation on what responsibilities FunctorBase.h has, compared
to TaskBase.
