Function std::cuda_sync

int cuda_sync()

cuda_write returns once 'host' may be reused. Copies of 1 MiB and up run as 4 parallel lanes (3 helper threads started on first use plus the caller), each staging its slice through pinned buffers with the DMA of one chunk overlapping the copy of the next: ~2x the driver's own pageable-memory path, which is bounded by one core's memcpy rate.

wait for all queued work