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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 module

shmem_api

This is a work-in-progress implementation of the OpenSHMEM spec, in the future both ROCSHMEM and NVSHMEM will be supported.

You can find the current specification at http://openshmem.org/site/sites/default/site_files/OpenSHMEM-1.6.pdf

The headings below corrosspond to section 9: OpenSHMEM Library API.

comptime values​

SHMEM_CMP_EQ​

comptime SHMEM_CMP_EQ = NVSHMEM_CMP_EQ

SHMEM_CMP_GE​

comptime SHMEM_CMP_GE = NVSHMEM_CMP_GE

SHMEM_CMP_GT​

comptime SHMEM_CMP_GT = NVSHMEM_CMP_GT

SHMEM_CMP_LE​

comptime SHMEM_CMP_LE = NVSHMEM_CMP_LE

SHMEM_CMP_LT​

comptime SHMEM_CMP_LT = NVSHMEM_CMP_LT

SHMEM_CMP_NE​

comptime SHMEM_CMP_NE = NVSHMEM_CMP_NE

SHMEM_CMP_SENTINEL​

comptime SHMEM_CMP_SENTINEL = NVSHMEM_CMP_SENTINEL

SHMEM_SIGNAL_ADD​

comptime SHMEM_SIGNAL_ADD = NVSHMEM_SIGNAL_ADD

SHMEM_SIGNAL_SET​

comptime SHMEM_SIGNAL_SET = NVSHMEM_SIGNAL_SET

SHMEM_TEAM_INVALID​

comptime SHMEM_TEAM_INVALID = Int32(-1)

SHMEM_TEAM_NODE​

comptime SHMEM_TEAM_NODE = Int32(2)

SHMEM_TEAM_SHARED​

comptime SHMEM_TEAM_SHARED = Int32(1)

shmem_team_t​

comptime shmem_team_t = c_int

SHMEM_TEAM_WORLD​

comptime SHMEM_TEAM_WORLD = Int32(0)

Structs​

  • ​SHMEMScope: Enables following the OpenSHMEM spec by default for put/get/iput/iget etc. While allowing NVIDIA extensions for block and warp scopes by passing a parameter.
  • ​SHMEMUniqueID: Unique ID that must be identical across all threads and nodes to establish communication.

Functions​

  • ​shmem_barrier_all: Registers the arrival of a PE at a barrier and blocks the PE until all other PEs arrive at the barrier and all local updates and remote memory updates on the default context are completed.
  • ​shmem_barrier_all_on_stream: Mechanism for synchronizing all PEs at once. This routine blocks the calling PE until all PEs have called nvshmem_barrier_all. In a multithreaded NVSHMEM program, only the calling thread is blocked, however, it may not be called concurrently by multiple threads in the same PE.
  • ​shmem_calloc: Collectively allocate a zeroed block of symmetric memory.
  • ​shmem_create_uniqueid: Create a unique ID for rocSHMEM TCP bootstrap.
  • ​shmem_fence: Ensures ordering of delivery of operations on symmetric data objects.
  • ​shmem_finalize: A collective operation that releases all resources used by SHMEM.
  • ​shmem_free: Collectively deallocate symmetric memory.
  • ​shmem_g: Copies one data item from a remote PE.
  • ​shmem_get: Copies data from a specified PE.
  • ​shmem_get_nbi: Initiate a non-blocking copy of data from a specified PE.
  • ​shmem_init: A collective operation that allocates and initializes the resources used by the SHMEM library.
  • ​shmem_init_thread_mpi: Modular-specific init that enables initializing SHMEM on one GPU per thread.
  • ​shmem_init_thread_tcp: Modular-specific init that enables initializing SHMEM on one GPU per thread using TCP bootstrapping, without mpirun or other launchers. The bootstrap will wait until total_nodes * gpus_per_node have completed the exchange of information before moving on from this function call.
  • ​shmem_malloc: Collectively allocate symmetric memory.
  • ​shmem_module_finalize: Finalizes the device state in the compiled function module and cleans up NVSHMEM operations. This should be called when NVSHMEM operations are no longer needed for the given device function.
  • ​shmem_module_init: Initializes the device state in the compiled function module so that it's able to perform SHMEM operations. Must have completed device initialization prior to calling this function.
  • ​shmem_my_pe: Returns the number of the calling PE.
  • ​shmem_n_pes: Returns the number of PEs running in a program.
  • ​shmem_p: Copies one data item to a remote PE.
  • ​shmem_put: Copy data from a contiguous local data object to a data object on a specified PE.
  • ​shmem_put_nbi: Initiate a non-blocking copy of data from a contiguous local data object to a data object on a specified PE.
  • ​shmem_put_signal_nbi: The nonblocking put-with-signal routines provide a method for copying data from a contiguous local data object to a data object on a specified PE and subsequently updating a remote flag to signal completion.
  • ​shmem_signal_op: The nvshmemx_signal_op operation atomically updates sig_addr with signal using operation sig_op on the specified PE. This operation can be used together with wait and test routines for efficient point-to-point synchronization.
  • ​shmem_signal_wait_until: Wait for a variable on the local PE to change from a signaling operation.
  • ​shmem_team_my_pe: Returns the number of the calling PE within a specified team.

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