86 lines
2.8 KiB
ReStructuredText
86 lines
2.8 KiB
ReStructuredText
|
.. _libcudacxx-ptx-examples-st-async:
|
||
|
|
|
||
|
|
How to use st.async
|
||
|
|
===================
|
||
|
|
|
||
|
|
.. code:: cuda
|
||
|
|
|
||
|
|
#include <cstdio>
|
||
|
|
#include <cuda/ptx>
|
||
|
|
#include <cuda/barrier>
|
||
|
|
#include <cooperative_groups.h>
|
||
|
|
|
||
|
|
__global__ void __cluster_dims__(8, 1, 1) kernel()
|
||
|
|
{
|
||
|
|
using cuda::ptx::sem_release;
|
||
|
|
using cuda::ptx::sem_acquire;
|
||
|
|
using cuda::ptx::space_cluster;
|
||
|
|
using cuda::ptx::space_shared;
|
||
|
|
using cuda::ptx::scope_cluster;
|
||
|
|
|
||
|
|
namespace cg = cooperative_groups;
|
||
|
|
cg::cluster_group cluster = cg::this_cluster();
|
||
|
|
|
||
|
|
using barrier_t = cuda::barrier<cuda::thread_scope_block>;
|
||
|
|
|
||
|
|
#pragma nv_diag_suppress static_var_with_dynamic_init
|
||
|
|
__shared__ int receive_buffer[4];
|
||
|
|
__shared__ barrier_t bar;
|
||
|
|
init(&bar, blockDim.x);
|
||
|
|
|
||
|
|
// Sync cluster to ensure remote barrier is initialized.
|
||
|
|
cluster.sync();
|
||
|
|
|
||
|
|
// Get address of remote cluster barrier:
|
||
|
|
unsigned int other_block_rank = cluster.block_rank() ^ 1;
|
||
|
|
uint64_t * remote_bar = cluster.map_shared_rank(cuda::device::barrier_native_handle(bar), other_block_rank);
|
||
|
|
// int * remote_buffer = cluster.map_shared_rank(&receive_buffer, other_block_rank);
|
||
|
|
int * remote_buffer = cluster.map_shared_rank(&receive_buffer[0], other_block_rank);
|
||
|
|
|
||
|
|
// Arrive on local barrier:
|
||
|
|
uint64_t arrival_token;
|
||
|
|
if (threadIdx.x == 0) {
|
||
|
|
// Thread 0 arrives and indicates it expects to receive a certain number of bytes as well
|
||
|
|
arrival_token = cuda::ptx::mbarrier_arrive_expect_tx(sem_release, scope_cluster, space_shared, cuda::device::barrier_native_handle(bar), sizeof(receive_buffer));
|
||
|
|
} else {
|
||
|
|
arrival_token = cuda::ptx::mbarrier_arrive(sem_release, scope_cluster, space_shared, cuda::device::barrier_native_handle(bar));
|
||
|
|
}
|
||
|
|
|
||
|
|
if (threadIdx.x == 0) {
|
||
|
|
printf("[block %d] arrived with expected tx count = %llu\n", cluster.block_rank(), sizeof(receive_buffer));
|
||
|
|
}
|
||
|
|
|
||
|
|
// Send bytes to remote buffer, arriving on remote barrier
|
||
|
|
if (threadIdx.x == 0) {
|
||
|
|
cuda::ptx::st_async(remote_buffer, {int(cluster.block_rank()), 2, 3, 4}, remote_bar);
|
||
|
|
}
|
||
|
|
|
||
|
|
if (threadIdx.x == 0) {
|
||
|
|
printf("[block %d] st_async to %p, %p\n",
|
||
|
|
cluster.block_rank(),
|
||
|
|
remote_buffer,
|
||
|
|
remote_bar
|
||
|
|
);
|
||
|
|
}
|
||
|
|
|
||
|
|
// Wait on local barrier:
|
||
|
|
while(!cuda::ptx::mbarrier_try_wait(sem_acquire, scope_cluster, cuda::device::barrier_native_handle(bar), arrival_token)) {}
|
||
|
|
|
||
|
|
// Print received values:
|
||
|
|
if (threadIdx.x == 0) {
|
||
|
|
printf(
|
||
|
|
"[block %d] receive_buffer = { %d, %d, %d, %d }\n",
|
||
|
|
cluster.block_rank(),
|
||
|
|
receive_buffer[0], receive_buffer[1], receive_buffer[2], receive_buffer[3]
|
||
|
|
);
|
||
|
|
}
|
||
|
|
|
||
|
|
}
|
||
|
|
|
||
|
|
int main() {
|
||
|
|
kernel<<<8, 128>>>();
|
||
|
|
cudaDeviceSynchronize();
|
||
|
|
}
|
||
|
|
|
||
|
|
`See it on Godbolt <https://cuda.godbolt.org/z/36GdbGdbf>`_
|