DPCT1019

Intel® DPC++ Compatibility Tool Developer Guide and Reference

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ID 768918

Date 10/31/2024

Version

Public

Visible to Intel only — GUID: GUID-D65DA6DC-9D19-490A-B4A4-35DFEAB03922

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DPCT1019

Message

local_mem_size in SYCL is not a complete equivalent of <variable name> in CUDA. You may need to adjust the code.

Detailed Help

In CUDA*, the sharedMemPerBlock reports the size of the shared memory in bytes available per block. The SYCL* equivalent of a CUDA block is a work-group. The SYCL equivalent of shared memory is local memory. There is no limitation on the size of the local memory per work-group in SYCL. There is a limit on the maximum size of the local memory in bytes available per compute unit, which is exposed by the info::device::local_mem_size device descriptor in SYCL.

Suggestions to Fix

Verify the code correctness.

For example, this original CUDA code:

void foo() {
  cudaDeviceProp prop;
  cudaGetDeviceProperties(&prop, 0);
  if (prop.sharedMemPerBlock >= threshold) {
    // submit the task
    Code piece A
  } else {
    // change the block size or block number
    Code piece B
  }
}

results in the following migrated SYCL code:

void foo() {
  dpct::device_info prop;
  dpct::dev_mgr::instance().get_device(0).get_device_info(prop);
  /*
  DPCT1019:0: local_mem_size in SYCL is not a complete equivalent of
  sharedMemPerBlock in CUDA. You may need to adjust the code.
  */
  if (prop.get_local_mem_size() >= threshold) {
    // submit the task
    Code piece A
  } else {
    // change the block size or block number
    Code piece B
  }
}

which is rewritten to:

void foo() {
  dpct::device_info prop;
  dpct::dev_mgr::instance().get_device(0).get_device_info(prop);
  if (prop.get_local_mem_size() >= threshold) {
    // submit the task
    Code piece A
  } else {
    // change the block size or block number
    Code piece B
  }
}

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Intel® DPC++ Compatibility Tool Developer Guide and Reference

DPCT1019

Message

Detailed Help

Suggestions to Fix