Intel® Advisor User Guide

User Guide

Contents

Set Up Environment to Offload DPC++, OpenMP* target, and OpenCL™ Applications to CPU

If you have an application that contains Data Parallel C++ (DPC++), C++/Fortran with OpenMP* target, or OpenCL™ code and prepared for offloading to a target device, you can analyze and model its potential performance on a different target device with the it with the
Intel® Advisor
.
To do this, use
CPU offload profiling
 to offload your code temporarily to a CPU so that you can profile it and model its performance with the
Offload Modeling
 perspective.
Offload your DPC++, C++/Fortran with OpenMP target, or OpenCL code to CPU
only
 to analyze it with the CPU-to-GPU
Offload Modeling
 workflow. To analyze it with the
GPU-to-GPU Offload Modeling workflow
or
GPU Roofline
 workflow, configure your system to analyze GPU kernels instead.
Depending on your operating system, do one of the following:

Linux* OS

  1. For
    DPC++ code
    : Force offloading to a CPU using one of the following:
    • Recommended
      : Set the
      SYCL_DEVICE_FILTER
       environment variable as follows: 
      export SYCL_DEVICE_FILTER=opencl:cpu
    • If your application uses a SYCL device selector:
      1. In the application source code, add the following to specify the CPU as the target device: 
        sycl::cpu_selector
        For details, see Device selectors in the DPC++ Reference.
      2. Rebuild the application,
  2. For
    OpenMP code
    : Force offloading to a CPU with one of the following:
    • Recommended
      : To offload code to CPU, set the following environment variables: 
      export OMP_TARGET_OFFLOAD=MANDATORY
      export LIBOMPTARGET_DEVICETYPE=CPU
      export LIBOMPTARGET_PLUGIN=OPENCL
    • To run code natively on CPU, set the following variable: 
      export OMP_TARGET_OFFLOAD=DISABLED
  3. If your application uses
    OpenCL code
    : Configure your code to be offloaded to a CPU. Refer to the OpenCL documentation at https://www.khronos.org/registry/OpenCL/ for specific instructions.

Windows* OS

  1. Set the following environment variable to use the JIT profiling API: 
    set INTEL_JIT_BACKWARD_COMPATIBILITY=1
  2. For
    DPC++ code
    : Force offloading to a CPU using one of the following:
    • Recommended
      : Set the
      SYCL_DEVICE_FILTER
       environment variable as follows: 
      set SYCL_DEVICE_FILTER=opencl:cpu
    • If your application uses a SYCL device selector:
      1. In the application source code, add the following to specify the CPU as the target device: 
        sycl::cpu_selector
        For details, see Device selectors in the DPC++ Reference.
      2. Rebuild the application,
  3. For
    OpenMP code
    : Force offloading to a CPU with one of the following:
    • Recommended
      : To offload code to CPU, set the following environment variables: 
      set OMP_TARGET_OFFLOAD=MANDATORY
      set LIBOMPTARGET_DEVICETYPE=CPU
      set LIBOMPTARGET_PLUGIN=OPENCL
    • To run code natively on CPU, set the following variable: 
      set OMP_TARGET_OFFLOAD=DISABLED
  4. If your application uses
    OpenCL code
    : Configure your code to be offloaded to a CPU. Refer to the OpenCL documentation at https://www.khronos.org/registry/OpenCL/ for specific instructions.

Next Steps

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.