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29 Mar 2024 11:58:07 EDT (-0400)
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From: jhu
Subject: OMG, super fast compiling
Date: 16 Aug 2012 02:00:06
Message: <web.502c8bb36f907f46d19b0ec40@news.povray.org>
make -j x

where "x" is the number of total threads the processor supports. Am I the only
who didn't know about this???


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From: Le Forgeron
Subject: Re: OMG, super fast compiling
Date: 16 Aug 2012 02:16:23
Message: <502c9037@news.povray.org>
Le 16/08/2012 07:57, jhu a écrit :
> make -j x
> 
> where "x" is the number of total threads the processor supports. Am I the only
> who didn't know about this???

How would I know ? But yes for me.

In fact x > total threads in processor is also a good x: due to the
large I/O on spinning disk a compilation requires, a perfect match is
full of wait. (with N the number of threads supported by the
processor(s), N <= x <= 2*N )

When using SSD, that might be a different story.


-- 
Real software engineers work from 9 to 5, because that is
the way the job is described in the formal spec.  Working
late would feel like using an undocumented external procedure.


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From: Warp
Subject: Re: OMG, super fast compiling
Date: 16 Aug 2012 10:25:51
Message: <502d02ef@news.povray.org>
jhu <nomail@nomail> wrote:
> make -j x

> where "x" is the number of total threads the processor supports. Am I the only
> who didn't know about this???

Yes?

-- 
                                                          - Warp


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From: waggy
Subject: Re: OMG, super fast compiling
Date: 16 Aug 2012 12:25:00
Message: <web.502d1e0b950df5ba9726a3c10@news.povray.org>
"jhu" wrote:
> make -j x
>
> where "x" is the number of total threads the processor supports. Am I the only
> who didn't know about this???

No, and thank you for posting it.  I'll include a note about this in the
package-specifc instructions I post from time to time.

I don't even recall seeing this when looking at a few compile-from-source Linux
distributions a few months ago...  Ah, here it is.

Note
For many modern systems with multiple processors (or cores) the compilation time
for a package can be reduced by performing a "parallel make" by either setting
an environment variable or telling the make program how many processors are
available. For instance, a Core2Duo can support two simultaneous processes with:

export MAKEFLAGS='-j 2'
or just building with:

make -j2
When multiple processors are used in this way, the SBU units in the book will
vary even more than they normally would. Analyzing the output of the build
process will also be more difficult because the lines of different processes
will be interleaved. If you run into a problem with a build step, revert back to
a single processor build to properly analyze the error messages.

From:
http://www.linuxfromscratch.org/lfs/view/stable/chapter04/aboutsbus.html


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