svn commit: r263778 - in head: bin lib lib/clang sbin share/mk usr.bin usr.sbin

[John Baldwin]

On Wednesday, March 26, 2014 6:30:39 pm Dimitry Andric wrote:
> Author: dim
> Date: Wed Mar 26 22:30:38 2014
> New Revision: 263778
> URL: http://svnweb.freebsd.org/changeset/base/263778
> 
> Log:
>   Add a SUBDIR_PARALLEL option to bsd.subdir.mk, to allow make to process
>   all the SUBDIR entries in parallel, instead of serially.  Apply this
>   option to a selected number of Makefiles, which can greatly speed up the
>   build on multi-core machines, when using make -j.
>   
>   This can be extended to more Makefiles later on, whenever they are
>   verified to work correctly with parallel building.
>   
>   I tested this on a 24-core machine, with make -j48 buildworld (N = 6):
>   
>                   before    stddev       after    stddev
>                   =======   ======       =======  ======
>   real time        1741.1     16.5         959.8     2.7
>   user time       12468.7     16.4       14393.0    16.8
>   sys  time        1825.0     54.8        2110.6    22.8
>   
>   (user+sys)/real     8.2                   17.1
>   
>   E.g. the build was approximately 45% faster in real time.  On machines
>   with less cores, or with lower -j settings, the speedup will not be as
>   impressive.  But at least you can now almost max out a machine with
>   buildworld!
>   
>   Submitted by:	jilles
>   MFC after:	2 weeks

Nice!

-- 
John Baldwin