@pengzhao-intel @xinyu-intel

Thanks @TaoLv it will be very convenient for the end-user :)

@ZhennanQin please create INT8 doc in this folder after this PR merge.
@ciyongch please create RNN doc in this folder too

Because lot of outside pages reference the MKLDNN_README.
Could we keep the original page (maybe only link) to avoid 404?

@mxnet-label-bot add[Doc, Example, pr-awaiting-review]

@aaronmarkham Could you help to review the change?

@aaronmarkham Thank you for your kind suggestion. Currently, pip install mxnet doesn't have MKL-DNN enabled but mxnet-mkl does. Do you still think we need update the document to describe what's provided in mxnet-mkl and what's suggested for Windows build? @xinyu-intel

@aaronmarkham If yes, do you think we can do that in another PR? In this PR, I just try to move the document and make it visible on the web page, not intending to change any content in it.

friendly ping @aaronmarkham

Any comments? @aaronmarkham

Sorry, I thought I already replied. We can do the docs update in a separate PR, but I wanted to flag that it should be done soon.

I was under the impression that MKL-DNN was on by default. I guess this must be in the build from source route then?

I ran into those subprocess issues. Should this be mentioned somewhere? Add a mention of KMP_INIT_AT_FORK=false - or maybe that needs to be thrown into the makefile to prevent problems?

Help me untangle what is what.
If you have already installed MKL and you pip install mxnet, what happens?
If you have already installed MKL-DNN and you pip install mxnet, what happens?
If you have already installed both MKL and MKL-DNN and you pip install mxnet, what happens?
If you have not installed either and you pip install mxnet-mkl, what happens?
If you have not installed either and you pip install mxnet, what happens?
If you have already installed MKL and you build from source (with default flags), what happens? I reported this issue where it doesn't work (on Windows): #11769
If you have already installed MKL-DNN and you build from source (with default flags), what happens?
What other variations pop up when we consider Apple or Linux or Edge?

I was under the impression that MKL-DNN was on by default. I guess this must be in the build from source route then?

Yes, MKL-DNN is on by default when build from source. For pypi package mxnet, it is explicitly turned off.

I ran into those subprocess issues. Should this be mentioned somewhere? Add a mention of KMP_INIT_AT_FORK=false - or maybe that needs to be thrown into the makefile to prevent problems?

I thought it's an issue of iomp not mxnet and someone is already working on it. I will track the progress of it. If it does not seem to be fixed soon, I will add it somewhere in the document.

If you have already installed MKL and you pip install mxnet, what happens?
If you have already installed MKL-DNN and you pip install mxnet, what happens?
If you have already installed both MKL and MKL-DNN and you pip install mxnet, what happens?

MXNet should run into openblas and native CPU implementation. MKL and MKL-DNN code is not compiled into mxnet pypi package - the code is wrapped with compiling flags MSHADOW_USE_MKL or MXNET_USE_MKLDNN.

If you have not installed either and you pip install mxnet-mkl, what happens?
If you have not installed either and you pip install mxnet, what happens?

mxnet-mkl/mxnet should work properly. It doesn't depend on any external installed package - MKL is statically linked and mkldnn.so is distributed with mxnet-mkl pypi package.

If you have already installed MKL and you build from source (with default flags), what happens? I reported this issue where it doesn't work (on Windows): #11769

You should explicitly use USE_BLAS=mkl to link MKL as BLAS library. USE_MKLDNN=1 should not affect the option choice. You issue looks like a cmake issue of mshadow to me.

If you have already installed MKL-DNN and you build from source (with default flags), what happens?

MXNet has its bundled MKL-DNN sub-module. The sub-module will be compiled and linked when USE_MKLDNN=1. External installed MKL-DNN package should not affect the process of build from source without some hack to the makefile or the link path.

What other variations pop up when we consider Apple or Linux or Edge?

Should share the similar methodology. One exception is that currently MKL-DNN is enabled by default only when build from source on linux + x86.

@aaronmarkham I have created #14399 to track the document improvement effort. Do you think this PR is good to merge and we can move forward now?

@aaronmarkham do you have any other suggestion for our plan?
We're working on improving the MKLDNN documents.

If this is no other comment, I will merge this PR in 24 hours as the first step of doc enhancement.

I think the separate issue to track the docs needs is great! Go ahead with this one.

Thanks, @aaronmarkham I am merging now :)

Thank you @aaronmarkham . Feel free to comment in #14399 if you have any suggestion or question about MKL-DNN documentation.