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Modify 05_slice example to use DefaultExecutionSpace #677

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Modify 05_slice example to use DefaultExecutionSpace #677

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24 changes: 13 additions & 11 deletions example/core_tutorial/05_slice/slice_example.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -56,16 +56,15 @@ void sliceExample()
const int VectorLength = 4;

/*
Finally declare the memory space in which the AoSoA will be allocated. In
this example we are writing basic loops that will execute on the CPU. The
HostSpace allocates memory in standard CPU RAM.
The current example uses default spaces to work across all supported
backends, but explicit choices like HostSpace and CudaSpace can also be
used.

Kokkos also supports execution on GPUs. For example, to create an AoSoA
allocated on NVIDIA devices use `Kokkos::CudaSpace` instead of
`Kokkos::HostSpace`.
We declare the memory space in which the AoSoA will be allocated
on the default execution space we are dealing with.
Comment on lines +63 to +64
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Suggested change
We declare the memory space in which the AoSoA will be allocated
on the default execution space we are dealing with.
We create the AoSoA particle data in the memory space associated
with the default execution space (see https://kokkos.github.io/kokkos-core-wiki/ProgrammingGuide/Initialization.html).

*/
using MemorySpace = Kokkos::HostSpace;
using ExecutionSpace = Kokkos::DefaultHostExecutionSpace;
using ExecutionSpace = Kokkos::DefaultExecutionSpace;
using MemorySpace = typename ExecutionSpace::memory_space;
using DeviceType = Kokkos::Device<ExecutionSpace, MemorySpace>;
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Just a note that #585 will change most of the examples to use memory_space directly - it may be best to wait until that is merged

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Sure, I will update the rest of the examples after #585 is merged. Will keep the PR open until then.

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@dineshadepu should be okay to continue this PR now that we've merged the blocking PR - let me know if those changes are confusing in any way. But I do not plan to include this in the imminent release, so feel free to wait until that's finished


/*
Expand All @@ -78,6 +77,9 @@ void sliceExample()
Cabana::AoSoA<DataTypes, DeviceType, VectorLength> aosoa( "my_aosoa",
num_tuple );

// Create a mirror view of the aosoa on the host for accessing it legally
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Suggested change
// Create a mirror view of the aosoa on the host for accessing it legally
// Create a mirror of the AoSoA on the host (this will not make a new copy if the memory is already allocated on the host, but will if it is in device memory) in order to print out the data.

auto aosoa_host =
Cabana::create_mirror_view_and_copy( Kokkos::HostSpace(), aosoa );
/*
Create a slice over each tuple member in the AoSoA. An integer template
parameter is used to indicate which member to slice. A slice object
Expand All @@ -88,9 +90,9 @@ void sliceExample()
because slices are unmanaged memory but may still be used for diagnostic
purposes.
*/
auto slice_0 = Cabana::slice<0>( aosoa, "my_slice_0" );
auto slice_1 = Cabana::slice<1>( aosoa, "my_slice_1" );
auto slice_2 = Cabana::slice<2>( aosoa, "my_slice_2" );
auto slice_0 = Cabana::slice<0>( aosoa_host, "my_slice_0" );
auto slice_1 = Cabana::slice<1>( aosoa_host, "my_slice_1" );
auto slice_2 = Cabana::slice<2>( aosoa_host, "my_slice_2" );

/*
Let's initialize the data using the 2D indexing scheme. Slice data can
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