DPCT1124

Intel® DPC++ Compatibility Tool Developer Guide and Reference

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ID 768918

Date 6/24/2024

Version

Public

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DPCT1124

Message

<API name> is migrated to asynchronous memcpy API. While the origin API might be synchronous, it depends on the type of operand memory, so you may need to call wait() on event return by memcpy API to ensure synchronization behavior.

Detailed Help

Some CUDA* asynchronous API might be synchronous with respect to host. For example, asynchronous memcpy API might be synchronous in the following 3 cases: data transfers between device memory and pageable host memory, data transfers between host memory, and data transfers involving pinned memory.

Suggestions to Fix

For example, this original CUDA code:

cudaMemcpyAsync(host_dst, host_src, size, cudaMemcpyHostToHost);

results in the following migrated SYCL* code:

/*
DPCT1124:0: cudaMemcpyAsync is migrated to asynchronous memcpy API. While the
origin API might be synchronous, it depends on the type of operand memory, so
you may need to call wait() on event return by memcpy API to ensure
synchronization behavior.
*/
dpct::get_in_order_queue().memcpy(host_dst, host_src, size);

which needs to be rewritten to:

dpct::get_in_order_queue().memcpy(host_dst, host_src, size).wait();

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Intel® DPC++ Compatibility Tool Developer Guide and Reference

DPCT1124

Message

Detailed Help

Suggestions to Fix