CUDA and OpenCL

[Yong]

Hi,

It's said that Sailfish works on GPU with both CUDA and OpenCL. Is there a way to switch from using CUDA to OpenCL?

Thank you very much.

Best,

Yong

[Michal Januszewski]

You can use the --backend=opencl option. Note that you will need a working PyOpenCL on your system in order for this work.

--Michal

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[Y Wang]

Hi Michal,

Thanks for your information. I just had a try on a machine where I installed the latest opencl. With a simple test, the opencl can find 1 platform and 4 GPU devices. But finally I get following error message. Any suggestion? Thanks.

[wxw@cu01 2_cyl]$ python cylinder.py —backends=opencl

[  1187  INFO Master/cu01] Machine master starting with PID 26431 at 2016-01-08 12:39:32 UTC

[  1235  INFO Master/cu01] Sailfish version: 08b219240b900366df7fef0420a6d28d59cf366f

[  1236  INFO Master/cu01] Handling subdomains: [0]

[  1236  INFO Master/cu01] Subdomain -> GPU map: {0: 0}

[  6028  INFO Subdomain/0] Initializing subdomain.

Process Subdomain/0:

Traceback (most recent call last):

  File "/home/wxw/software/lib/python2.7/multiprocessing/process.py", line 232, in _bootstrap

    self.run()

  File "/home/wxw/software/lib/python2.7/multiprocessing/process.py", line 88, in run

    self._target(*self._args, **self._kwargs)

  File "/home/wxw/software/sailfish-cfd/sailfish/master.py", line 67, in _start_subdomain_runner

    runner.run()

  File "/home/wxw/software/sailfish-cfd/sailfish/subdomain_runner.py", line 1502, in run

    self._sim.init_fields(self)

  File "/home/wxw/software/sailfish-cfd/sailfish/lb_base.py", line 154, in init_fields

    gpu_array=field.gpu_array)

  File "/home/wxw/software/sailfish-cfd/sailfish/subdomain_runner.py", line 268, in make_scalar_field

    buf = self.backend.alloc_async_host_buf(self.num_phys_nodes, dtype=dtype)

  File "/home/wxw/software/sailfish-cfd/sailfish/backend_opencl.py", line 94, in alloc_async_host_buf

    return host_buf.get_host_array(shape, dtype)

  File "/home/wxw/software/lib/python2.7/site-packages/pyopencl-2015.2.4-py2.7-linux-x86_64.egg/pyopencl/cffi_cl.py", line 753, in get_host_array

    _size))

  File "/home/wxw/software/lib/python2.7/site-packages/pyopencl-2015.2.4-py2.7-linux-x86_64.egg/pyopencl/cffi_cl.py", line 549, in _handle_error

    raise e

LogicError: memoryobject.get host array failed: INVALID_VALUE - Only MemoryObject with USE_HOST_PTR is supported.

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[Y Wang]

I also tried with option "--opencl-interactive-select", then it stuck, even I chose 0 as default. 

[wxw@cu01 examples]$ python ldc_2d.py --backends=opencl --opencl-interactive-select

[  1150  INFO Master/cu01] Machine master starting with PID 12604 at 2016-01-08 14:30:35 UTC

[  1200  INFO Master/cu01] Sailfish version: 08b219240b900366df7fef0420a6d28d59cf366f

[  1200  INFO Master/cu01] Handling subdomains: [0]

[  1200  INFO Master/cu01] Subdomain -> GPU map: {0: 0}

Choose platform:

[0] <pyopencl.Platform 'NVIDIA CUDA' at 0x416d220>

Process Subdomain/0:

Traceback (most recent call last):

  File "/home/wxw/software/lib/python2.7/multiprocessing/process.py", line 232, in _bootstrap

    self.run()

  File "/home/wxw/software/lib/python2.7/multiprocessing/process.py", line 88, in run

    self._target(*self._args, **self._kwargs)

  File "/home/wxw/software/sailfish-cfd/sailfish/master.py", line 51, in _start_subdomain_runner

    backend = backend_class(config, gpu_id)

  File "/home/wxw/software/sailfish-cfd/sailfish/backend_opencl.py", line 34, in __init__

    self.ctx = cl.create_some_context(True)

  File "/home/wxw/software/lib/python2.7/site-packages/pyopencl-2015.2.4-py2.7-linux-x86_64.egg/pyopencl/__init__.py", line 1270, in create_some_context

    answer = get_input("Choice [0]:")

  File "/home/wxw/software/lib/python2.7/site-packages/pyopencl-2015.2.4-py2.7-linux-x86_64.egg/pyopencl/__init__.py", line 1254, in get_input

    user_input = input(prompt)

EOFError: EOF when reading a line

Choice [0]:0