svn commit: r263778 - in head: bin lib lib/clang sbin share/mk usr.bin usr.sbin
John Baldwin
jhb at freebsd.org
Thu Mar 27 15:28:05 UTC 2014
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
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