For the complete documentation index, see llms.txt. Markdown versions of all pages are available by appending .md to any URL (e.g. /max/get-started.md).

Mojo function

smem_descriptor

def smem_descriptor[dtype: DType, //, *, BMN: Int, BK: Int, swizzle_mode: TensorMapSwizzle, is_k_major: Bool, page_dense: Bool = False](ptr: Pointer[Scalar[dtype], address_space=AddressSpace.SHARED, _safe=False]) -> MMASmemDescriptorPair

Creates an MMASmemDescriptorPair for an SM100 MMA operand tile in shared memory.

Selects either K-major or MN-major tile layout based on is_k_major, builds the canonical descriptor layout, and creates the corresponding pair of SMEM descriptors used by the SM100 UMMA instructions.

Parameters:

dtype (DType): Element type of the operand.
BMN (Int): Block tile size along the M or N dimension.
BK (Int): Block tile size along the K dimension.
swizzle_mode (TensorMapSwizzle): Swizzle mode for the shared memory access pattern.
is_k_major (Bool): When True, uses K-major (A/Q@K') layout; when False, uses MN-major (V/P@V) layout.
page_dense (Bool): When True, selects the page-dense (row-major atoms) variant of the tile layout for the SM100 row-major page-fold path.

Args:

ptr (Pointer[Scalar[dtype], address_space=AddressSpace.SHARED, _safe=False]): Pointer into shared memory for the operand tile.

Returns:

MMASmemDescriptorPair: An MMASmemDescriptorPair ready for use with SM100 UMMA instructions.