why MKL and MKL-DNN can't be used simultaneously in ChooseBlas.cmake

[luchangli03]

if(MKL_FOUND)
if(USE_MKLDNN)
set(BLAS "open")
else()
set(BLAS "MKL")
endif()
endif()

[luchangli03]

in the 3rdparty/mshadow/cmake/mshadow.cmake
the codes are also
if(MKL_FOUND)
if(USE_MKLML_MKL)
set(BLAS "open")
else()
set(BLAS "MKL")
endif()
endif()
I can't understand

[marcoabreu]

@lebeg

[pengzhao-intel]

yes, it's a little trick and this is a piece of legacy code which we want to refine for a while.

You can refer to this discussion and @jinhuang415 can help with the details.
#10175

[jinhuang415]

@luchangli03 Currently cmake BLAS is hard coded based on MKL_FOUND and USE_MKLDNN, we think this is unreasonable and need to change, solutions like to provide an option to select the BLAS type (just like what Makefile does, and users can still use MKL blas even use MKLDNN), this suggestion is also listed in #10175 related slides as well.

[lanking520]

@mxnet-label-bot could you please label this as [build, cmake, mkldnn]

[lebeg]

I have fixed this issue with #11148 but the PR still has some problems.

[pengzhao-intel]

The latest CMake refactors the logic of MKL selection.
The problem is resolved so closing.