[Numpy-discussion] Numpy 1.7.0 with Intel MKL 11.0.2.146

[Warren Weckesser]

On 3/10/13, Warren Weckesser <warren.weckesser at gmail.com> wrote:
> On 3/10/13, QT <rdirective at gmail.com> wrote:
>> Dear all,
>>
>> I'm at my wits end.  I've followed Intel's own
>> instructions<http://software.intel.com/en-us/articles/numpyscipy-with-intel-mkl>on
>> how to compile Numpy with Intel MKL.  Everything compiled and linked
>> fine and I've installed it locally in my user folder...There is one nasty
>> problem.  When one calls the numpy library to do some computation, it
>> does
>> not use all of the available threads.  I have 8 "cores" on my machine and
>> it only uses 4 of them.  The MKL_NUM_THREADS environmental variable can
>> be
>> set to tune the number of threads but setting it to 8 does not change
>> anything.  Indeed, setting it to 3 does limit the threads to 3....What is
>> going on?
>
>
> Does your computer have 8 physical cores, or 4 cores that look like 8
> because of hyperthreading?
>


Here's why I ask this: http://software.intel.com/en-us/forums/topic/294954


> Warren
>
>
>>
>> As a comparison, the numpy (version 1.4.1, installed from yum, which uses
>> BLAS+ATLAS) uses all 8 threads.  I do not get this.
>>
>> You can run this test program
>>
>> python -mtimeit -s'import numpy as np; a = np.random.randn(1e3,1e3)'
>> 'np.dot(a, a)'
>>
>> There is one saving grace, the local numpy built with MKL is much faster
>> than the system's numpy.
>>
>> I hope someone can help me.  Searching the internet has been fruitless.
>>
>> Best,
>> Quyen
>>
>> My site.cfg for numpy (1.7.0)
>> [mkl]
>> library_dirs = /opt/intel/mkl/lib/intel64
>> include_dirs = /opt/intel/mkl/include
>> mkl_libs = mkl_rt
>> lapack_libs =
>>
>> I've edited line 37 of numpy/distutils/intelcompiler.py
>> self.cc_exe = 'icc -O3 -fPIC -fp-model strict -fomit-frame-pointer
>> -openmp
>> -parallel -DMKL_ILP64'
>>
>> Also line 54 of numpy/distutils/fcompiler/intel.py
>> return ['-i8 -xhost -openmp -fp-model strict']
>>
>> My .bash_profile also contains the lines:
>> source /opt/intel/bin/compilervars.sh intel64
>> source /opt/intel/mkl/bin/mklvars.sh intel64
>>
>> The above is needed to set the LD_LIBRARY_PATH so that Python can source
>> the intel dynamic library when numpy is called.
>>
>