Skip to main content

/

Docs

Nightly

v25.1

Log in

Mojo module

id

This module provides GPU thread and block indexing functionality.

It defines aliases and functions for accessing GPU grid, block, thread and cluster dimensions and indices. These are essential primitives for GPU programming that allow code to determine its position and dimensions within the GPU execution hierarchy.

Most functionality is architecture-agnostic, with some NVIDIA-specific features clearly marked. The module is designed to work seamlessly across different GPU architectures while providing optimal performance through hardware-specific optimizations where applicable.

Aliases​

  • ​block_dim = _BlockDim(): Contains the dimensions of the block as x, y, and z values (for example, block_dim.y)
  • ​block_id_in_cluster = _Cluster_BlockIdx(): Contains the block id of the threadblock within a cluster, as x, y, and z values.
  • ​block_idx = _BlockIdx(): Contains the block index in the grid, as x, y, and z values.
  • ​cluster_dim = _ClusterDim(): Contains the dimensions of the cluster, as x, y, and z values.
  • ​cluster_idx = _ClusterIdx(): Contains the cluster index in the grid, as x, y, and z values.
  • ​global_idx = _GridIdx(): Contains the global offset of the kernel launch, as x, y, and z values.
  • ​grid_dim = _GridDim(): Provides accessors for getting the x, y, and z dimensions of a grid.
  • ​thread_idx = _ThreadIdx(): Contains the thread index in the block, as x, y, and z values.

Functions​

  • ​lane_id: Returns the lane ID of the current thread within its warp.
  • ​sm_id: Returns the Streaming Multiprocessor (SM) ID of the current thread.