[OE-core] Building with OpenMP support in OE fails on #include <omp.h>

[Mike Looijmans]

On 02-03-15 18:31, Mike Looijmans wrote:
> On 02-03-15 16:45, Paul Eggleton wrote:
>> Hi Mike,
>>
>> On Monday 02 March 2015 15:54:04 Mike Looijmans wrote:
>>> Here's the problem, running in a devshell:
>>>
>>> # echo '#include <omp.h>' > /tmp/compileme.c
>>> # $CC -c -fopenmp /tmp/compileme.c
>>> /tmp/compileme.c:1:17: fatal error: omp.h: No such file or directory
>>>    #include <omp.h>
>>>                    ^
>>> compilation terminated.
>>>
>>>
>>> The #pragma's and linking of OpenMP work just fine, it's just the inclusion
>>> of omp.h that appears to fail.
>>>
>>> What I was actually trying to do is to activate OpenMP in OpenCV to get
>>> decent performance on a multicore ARM system. But this is holding me back
>>> now.
>>>
>>> Looking in the sysroots reveals that the include file is actually there:
>>>
>>> $ find tmp-glibc/sysroots/topic-miami-florida-med-xc7z030 -name omp.h
>>> tmp-glibc/sysroots/topic-miami-florida-med-xc7z030/usr/lib/gcc/arm-oe-linux-
>>> gnueabi/4.9.1/include/omp.h
>>
>> Funnily enough this is an issue I fixed a few weeks ago - here's the bug which
>> contains a link to the fix:
>>
>> https://bugzilla.yoctoproject.org/show_bug.cgi?id=7141
>
> Ah okay, I'll upgrade to current master and retest.
>
> If it works, I'll post the patch to make opencv build with openmp.

Hmm, OpenCV now builds fine with OpenMP support for my dual-core ARM system, I 
can also see that it now links to libgomp, but apparently it doesn't actually 
use any OpenMP threading, as none of the filters I've tried ever uses more 
than one thread to process the image data. So I guess actually activating 
OpenMP is just a pointless waste. But for those willing to try, just add this 
line to the opencv recipe:

EXTRA_OECMAKE += "-DWITH_OPENMP=ON"




Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


TOPIC Embedded Systems
Eindhovenseweg 32-C, NL-5683 KH Best
Postbus 440, NL-5680 AK Best
Telefoon: (+31) (0) 499 33 69 79
Telefax:  (+31) (0) 499 33 69 70
E-mail: mike.looijmans at topic.nl
Website: www.topic.nl

Please consider the environment before printing this e-mail

Topic zoekt gedreven (embedded) software specialisten!
http://topic.nl/vacatures/topic-zoekt-software-engineers/