MemoryTraits

MemoryTraits is the last template parameter of View.

Usage

using DefaultMT = Kokkos::MemoryTraits<>;
using UnmanagedMT = Kokkos::MemoryTraits<Kokkos::Unmanaged>;
using AtomicRandomAccessMT =
    Kokkos::MemoryTraits<Kokkos::Atomic | Kokkos::RandomAccess>;

Struct Interface

template<unsigned N>
struct MemoryTraits

When provided to a multidimensional View, MemoryTraits allow passing extra information about the treatment of the allocation. The template argument is expected to be a bitwise OR of enumeration values described below.

Changed in version 4.7: 0 was added as the default value for the template parameter N.

template <unsigned N = 0>
struct MemoryTraits;

Nested type

type memory_traits

A tag type signifying the memory access trait(s) denoted by N.

Member Variables

static constexpr bool is_unmanaged

A boolean that indicates whether the Unmanaged trait is enabled.

static constexpr bool is_random_access

A boolean that indicates whether the RandomAccess trait is enabled.

static constexpr bool is_atomic

A boolean that indicates whether the Atomic trait is enabled.

static constexpr bool is_restrict

A boolean that indicates whether the Restrict trait is enabled.

static constexpr bool is_aligned

A boolean that indicates whether the Aligned trait is enabled.

Non-Member Enums

The following enumeration values are used to specify the memory access traits. Check the sub-section on memory access traits in the Programming Guide for further information about how these traits can be used in practice.

enum MemoryTraitsFlags

The following enumeration values are defined in this enumeration type.

enumerator Unmanaged

This traits means that Kokkos does neither reference counting nor automatic deallocation for such Views. This trait can be associated with memory allocated in any memory space. For example, an unmanaged view can be created by wrapping raw pointers of allocated memory, while also specifying the execution or memory space accordingly.

enumerator RandomAccess

Views that are going to be accessed irregularly (e.g., non-sequentially) can be declared as random access.

enumerator Atomic

In such a view, every access (read or write) to any element will be atomic.

enumerator Restrict

This trait indicates that the memory of this view doesn’t alias/overlap with another data structure in the current scope.

enumerator Aligned

This trait provides additional information to the compiler that the memory allocation in this View has an alignment of 64.

Non-Member Type aliases

The following type aliases are also available in the Kokkos namespace.

using MemoryManaged = MemoryTraits<0>;

Deprecated since version 4.7: The MemoryManaged alias is deprecated. Use MemoryTraits<> instead. Note that prior Kokkos versions require an explicit 0 template argument.

using MemoryUnmanaged = MemoryTraits<Unmanaged>;

using MemoryRandomAccess = MemoryTraits<Unmanaged | RandomAccess>;

Changed in version 4.7: MemoryRandomAccess was changed to MemoryTraits<RandomAccess> and does not imply Unmanaged any more.

Example

Kokkos::View<DayaType,
             LayoutType,
             MemorySpace,
             Kokkos::MemoryTraits<SomeFlag | SomeOtherFlag>> my_view;