svn commit: r253002 - head

[Teske, Devin]

On Jul 7, 2013, at 2:15 PM, Alfred Perlstein wrote:

> On 7/7/13 2:01 PM, Garrett Cooper wrote:
>> Why the magic number 12?
> 
> Numbers higher seem to result in worse performance as reported by some members of my team.
> 

We've run as high as -j48 ... number of logical cpu's "times-two" (it was on a box with 24 logical CPUs).

We did buildworld in under 9 minutes. Beyond the "times-two" rule we saw a slow-down.

NOTE: I might also mention this was on RAID-1 SSD.
-- 
Devin



>> On Jul 7, 2013, at 1:39 PM, Alfred Perlstein <alfred at FreeBSD.org> wrote:
>> 
>>> Author: alfred
>>> Date: Sun Jul  7 20:39:11 2013
>>> New Revision: 253002
>>> URL: http://svnweb.freebsd.org/changeset/base/253002
>>> 
>>> Log:
>>>  Document tip on how to build all kernels quickly.
>>> 
>>> Modified:
>>>  head/Makefile
>>> 
>>> Modified: head/Makefile
>>> ==============================================================================
>>> --- head/Makefile    Sun Jul  7 19:58:14 2013    (r253001)
>>> +++ head/Makefile    Sun Jul  7 20:39:11 2013    (r253002)
>>> @@ -32,6 +32,12 @@
>>> # targets             - Print a list of supported TARGET/TARGET_ARCH pairs
>>> #                       for world and kernel targets.
>>> # toolchains          - Build a toolchain for all world and kernel targets.
>>> +#
>>> +# "quick" way to test all kernel builds:
>>> +#    _jflag=`sysctl -n hw.ncpu`
>>> +#    _jflag=$(($_jflag * 2))
>>> +#    [ $_jflag -gt 12 ] && _jflag=12
>>> +#    make universe -DMAKE_JUST_KERNELS JFLAG=${jflag}
>>> #
>>> # This makefile is simple by design. The FreeBSD make automatically reads
>>> # the /usr/share/mk/sys.mk unless the -m argument is specified on the
>>> _______________________________________________
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>>> http://lists.freebsd.org/mailman/listinfo/svn-src-head
>>> To unsubscribe, send any mail to "svn-src-head-unsubscribe at freebsd.org"
> 

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