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.
This method is a remenant of when `ArrayHandle` could only store data on
one device at a time. It is now capable of storing data on any number of
devices (as well as the host), so asking for "the" device no longer
makes sense. Thus, this method is deprecated in favor of
`ArrayHandle::IsOnDevice`.
This deprecation leads to fixing some older functionality that still
assumed data could only be on one device at a time.
Fixes#592.
This class was used indirectly by the old `ArrayHandle`, through
`ArrayHandleTransfer`, to move data to and from a device. This
functionality has been replaced in the new `ArrayHandle`s through the
`Buffer` class (which can be compiled into libraries rather than make
every translation unit compile their own template).
This commit removes `ArrayManagerExecution` and all the implementations
that the device adapters were required to make. None of this code was in
any use anymore.
The `ArrayHandleStreaming` class stems from an old research project
experimenting with bringing data from an `ArrayHandle` in parts and
overlapping device transfer and execution. It works, but only in very
limited contexts. Thus, it is not actually used today. Plus, the feature
requires global indexing to be permutated throughout the worklet
dispatching classes of VTK-m for no further reason.
Because it is not really used, there are other more promising approaches
on the horizon, and it makes further scheduling improvements difficult,
we are removing this functionality.
Marked the old versions of PrepareFor* that do not use tokens as
deprecated and moved all of the code to use the new versions that
require a token. This makes the scope of the execution object more
explicit so that it will be kept while in use and can potentially be
reclaimed afterward.
The old version of ExecutionObject (that only takes a device) is still
supported, but you will get a deprecated warning if that is what is
defined.
Supporing this also included sending vtkm::cont::Token through the
vtkm::cont::arg::Transport mechanism, which was a change that propogated
through a lot of code.
This behaves just like `ScanExclusive`, but rather than returning the
total sum, it is appended to the end of the output array.
This is in preparation for the CellSetExplicit refactoring described in
issue #408.
BitFields are:
- Stored in memory using a contiguous buffer of bits.
- Accessible via portals, a la ArrayHandle.
- Portals operate on individual bits or words.
- Operations may be atomic for safe use from concurrent kernels.
The new BitFieldToUnorderedSet device algorithm produces an ArrayHandle
containing the indices of all set bits, in no particular order.
The new AtomicInterface classes provide an abstraction into bitwise
atomic operations across control and execution environments and are used
to implement the BitPortals.
VTK-m has been updated to replace old per device benchmark executables with a device
dependent shared library so that it's able to accept a device adapter at runtime through
the "--device=" argument.
VTK-m has been updated to replace old per device worklet testing executables with a device
dependent shared library so that it's able to accept a device adapter
at runtime.
Meanwhile, it updates the testing infrastructure APIs. vtkm::cont::testing::Run
function would call ForceDevice when needed and if users need the device
adapter info at runtime, RunOnDevice function would pass the adapter into the functor.
Optional Parser is bumped from 1.3 to 1.7.
In some functors within Algorithm.h, the functor did not have a
default constructor that initialized its fields. This could in turn
lead to a warning about using it unitialized.
Now that the dispatcher does its own TryExecute, filters do not need to
do that. This change requires all worklets called by filters to be able
to execute without knowing the device a priori.
This is a subclass of ExecutionObject and a superset of its
functionality. In addition to having a PrepareForExecution method, it
also has a PrepareForControl method that gets an object appropriate for
the control environment. This is helpful for situations where you need
code to work in both environments, such as the functor in an
ArrayHandleTransform.
Also added several runtime checks for execution objects and execution
and cotnrol objects.
By making is_base_of part of PrepareArgForExec, we can shorten not only
the C++ code but also the code that is generated by it.
Also, return && instead of by value when passing through the argument.
Changes thanks to Robert Maynard.
Most of the arguments given to device adapter algorithms are actually
control-side arguments that get converted to execution objects internally
(usually a `vtkm::cont::ArrayHandle`). However, some of the algorithms,
take an argument that is passed directly to the execution environment, such
as the predicate argument of `Sort`. If the argument is a plain-old-data
(POD) type, which is common enough, then you can just pass the object
straight through. However, if the object has any special elements that have
to be transferred to the execution environment, such as internal arrays,
passing this to the `vtkm::cont::Algorithm` functions becomes
problematic.
To cover this use case, all the `vtkm::cont::Algorithm` functions now
support automatically transferring objects that support the `ExecObject`
worklet convention. If any argument to any of the `vtkm::cont::Algorithm`
functions inherits from `vtkm::cont::ExecutionObjectBase`, then the
`PrepareForExecution` method is called with the device the algorithm is
running on, which allows these device-specific objects to be used without
the hassle of creating a `TryExecute`.
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