[cmake-developers] Is there an official FindMKL module?

Thu Aug 27 13:32:50 EDT 2015

Hi Siebren, 

I tried to link statically and it did not work for me, similar errors as to what you are getting. 

The way the macro is supposed to work -- it checks for the MKL link tool and if it is available, it uses and provides the libraries needed. If it is unavailable (or throws errors or whatever else the case may be), then FindBLAS reverts back to the way it handles MKL currently. 

I have attached the module that provides the interface to the MKL command line tool as well as the changed FindBLAS module that uses it. Major caveat here -- I have not used these since 2012, with one of the Intel 12.something compilers and CMake 2.8. I did a quick diff on the FindBLAS in the current version and the CMake 2.8 version and there's only very minor changes that shouldn't affect this working. If it turns out this is useful and close to functional, then we can work on getting it current. 

Tim 

----- Original Message -----

From: "Siebren Reker" <siebren.reker at gmail.com> 
To: "tim gallagher" <tim.gallagher at gatech.edu> 
Cc: cmake-developers at cmake.org 
Sent: Thursday, August 27, 2015 11:16:34 AM 
Subject: Re: [cmake-developers] Is there an official FindMKL module? 

Hi Tim, 

On Thu, Aug 27, 2015 at 4:32 PM, Tim Gallagher < tim.gallagher at gatech.edu > wrote: 

Siebren, 

We've never really used static linking so I am not sure if it ever really worked. I can try and let you know. 

Could you please do so? Just to verify that I'm not doing something obviously wrong 

<blockquote>

However, I'm having flashbacks here to something I thought I had done before. I dug through my emails and back in 2012 I had signed up to maintain a new module that provided a macro to interface with the MKL tool and generated the proper linking based on what it reported. My colleague and I had written it because we were tired of the difficulties in the current modules. This new module provided a macro and the FindBLAS and FindLAPACK modules would call the macro to get the link information. 

</blockquote>

Sounds clean, but are you sure the tool is always available? 

<blockquote>

I got push access to create the topic branch but then I don't know what happened. I don't know if I never pushed it, or it never got tested/approved/checked, no clue. I actually still have all of the modules and changes I had made, but it was in version 2.8. I wish I could remember if I had actually pushed it to CMake or not, but I really don't remember why it never happened. 

So anyway, now that we're discussing it again, if the CMake community wants the MKL support improved, I can dust off the modules and see what it would take to get it officially in the stream. 

</blockquote>

I'd be more than happy to test this. I've found a number of hits on Google for FindMKL.cmake files. I certainly wasn't alone in having trouble to get this to work (doesn't mean much of course). 

best, 
Siebren 

<blockquote>

Tim 

From: "Siebren Reker" < siebren.reker at gmail.com > 
To: "tim gallagher" < tim.gallagher at gatech.edu > 
Cc: cmake-developers at cmake.org 
Sent: Thursday, August 27, 2015 6:32:17 AM 
Subject: Re: [cmake-developers] Is there an official FindMKL module? 

Hi Tim, 

Quick add-on to my previous email. With BLA_STATIC ON, I see from the CMakeError.log that the static libraries ARE found (I was trusting the), but the linking of the test program goes wrong: 
undefined reference to `mkl_blas_sgemv` 
But that function IS implemented in one of the three libraries that is found, in my case in libmkl_sequential.a 

So this is probably a linking/ library ordering error. 
Indeed, Intel fora and the link advisor I mentioned earlier also report the need for grouping these as in 
-Wl,--start-group ${MKLROOT}/lib/intel64/libmkl_intel_lp64.a ${MKLROOT}/lib/intel64/libmkl_core.a ${MKLROOT}/lib/intel64/libmkl_sequential.a -Wl,--end-group 

Is my understanding correct, and can this be fixed? 

kind regards, 
Siebren 

On Thu, Aug 27, 2015 at 11:50 AM, Siebren Reker < siebren.reker at gmail.com > wrote: 

<blockquote>

Hi Tim, 

That is encouraging, thanks. I went back and tried harder this time, when I specified BLA_VENDOR precisely and leave BLA_STATIC off, I am able to get to the correct versions. 
In the very same directory where the shared libraries are found, I have the static libraries as well, but BLA_STATIC on in that case does not find the libraries. 

I've read up a bit on this now, so maybe the following information is helpful: 
This is a CMake 3.3.0 installation 
My project has both C and Fortran enabled 
I call it as follows: 

set( BLA_STATIC ON) 
set( BLA_VENDOR "Intel10_64lp_seq") 

find_package( BLAS ) 

Is BLA_STATIC = ON working for you? 

A separate question I have is if the linker command that will be produced afterwards is of course different from the one supplied by Intel in their tool. Should that not concern me? 

kind regards, 
Siebren 

On Wed, Aug 26, 2015 at 4:59 PM, Tim Gallagher < tim.gallagher at gatech.edu > wrote: 

<blockquote>

We sometime struggled to get it working, but we never had to resort to using a FindMKL -- FindBLAS and FindLAPACK work just fine for us, provided we do things "correctly." 

So long as we have sourced the mklvars script that ships with Intel MKL and we put: 

BLA_VENDOR =Intel10_64lp_seq ccmake /path/to/source/dir 
Then everything works fine and we have no issues. So we have to give CMake a hint that we want to pick the Intel version rather than the generic one (and we're using the sequential, 64bit MKL -- if you look in FindBLAS you can see other vendor types). 

Have you had things fail when you setup your environment variables using the scripts Intel provides and when you set the BLA_VENDOR hint as an environment variable? 

Tim 

From: "Siebren Reker" < siebren.reker at gmail.com > 
To: cmake-developers at cmake.org 
Sent: Wednesday, August 26, 2015 10:18:44 AM 
Subject: [cmake-developers] Is there an official FindMKL module? 

Hello, 

I am using the find_package() command to load settings for the Intel Math Kernel Library (MKL). This works through a custom FindMKL.cmake module that I've made for myself. 

However, when looking at: 
https://software.intel.com/en-us/articles/intel-mkl-link-line-advisor/ 

I can tell that what I've done is likely only correct for my specific case, and certainly not robust against library version changes and various other changes (openmp, static vs dynamic linking etc.). 

Instead of a FindMKL.cmake module, an alternative is to have MKL be discovered in the FindBLAS or FindLAPACK modules, but according to what I can find on the bug tracker, that solution is also in a fairly broken state: 

Bug 14138: http://www.cmake.org/Bug/view.php?id=14138 

Bug 13543: http://www.cmake.org/Bug/view.php?id=13543 

Bug 13528: http://www.cmake.org/Bug/view.php?id=13528 

Google tells me that many people have (like me) created their own FindMKL.cmake module, which are equally specific and tailored. 

Is anyone aware of a more "official" FindMKL module available somewhere, or at least something that is being somewhat maintained, either by someone at Kitware or Intel? Or of a plan to develop something like that? 

kind regards, 
Siebren Reker 
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</blockquote>

</blockquote>

</blockquote>

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