[CMake] Does Makefile generated by CMake support make -jN?

[Chaos Zhang]

Thanks for your reply Raymond, by 'If you got 96% both times, then I would
say there's a problem.', did you mean if make performed like this, it means
this project can't use make -jN? BTW, does CMake support some options to
turn on hardware acceleration?

Raymond Wan-2 wrote
> Hi Chao,
> 
> 
> On Wed, Jul 13, 2016 at 10:54 AM, Chaos Zhang <

> zcsd2012@

> > wrote:
>> I was trying to compile my project using CMake, after CMake generated
>> Makefile.
>> I used `/usr/bin/time -v make` to make the Makefile,  got the result:
>> 'Percent of CPU this job got: 96%'.
>> Then i used `/usr/bin/time -v make -j8` to make the Makefile, the result
>> of
>> CPU used is  'Percent of CPU this job got: 648%'.
>> So i wonder if Makefile generated by CMake support make -jN, BTW my CPU
>> is
>> I7-4790, and after i use 'cat /proc/cpuinfo', there are 8 processors.
> 
> 
> I'm not sure what you are asking...
> 
> You ran make with -j 8 and you got a percentage greater than 96% ...
> this implies that the Makefile does support -jN, doesn't it?  If you
> got 96% both times, then I would say there's a problem.
> 
> Is what you're wondering why it is 648% and not 800%?  I think that
> depends on the dependencies in your Makefile.  It's possible that some
> of them depend on each other in such a way that 8 parallel threads is
> not possible.
> 
> Also, I can't remember the value returned by /usr/bin/time -v, but I
> guess 648% is the average and not maximum.  So, perhaps there are
> parts within the Makefile that only one thread could be used and then
> it gets averaged out?
> 
> Ray
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