Buildworld times (was Re: svn commit: r350256 - in stable/12: . contrib/compiler-rt/lib/sanitizer_common contrib/libunwind/src contrib/llvm/lib/DebugInfo/DWARF contrib/llvm/lib/MC contrib/llvm/lib/Object contrib/llvm/lib/Ta...)

[Dimitry Andric]

On 24 Jul 2019, at 23:21, Dimitry Andric <dim at FreeBSD.org> wrote:
> 
> On 24 Jul 2019, at 22:56, mike tancsa <mike at sentex.net> wrote:
>> 
>> On 7/24/2019 1:21 PM, mike tancsa wrote:
>>> On 7/24/2019 12:02 PM, Dimitry Andric wrote:
> ...
>>> # cat /etc/src.conf /etc/make.conf
>>> MK_SYSTEM_COMPILER=no
>>> MK_SYSTEM_LINKER=no
>>> KERNCONF=server
>>> MK_SYSTEM_COMPILER=no
>>> MK_SYSTEM_LINKER=no
>> 
>> Hmmm, is the logic reversed somehow ?  The good news is if nothing is
>> defined, it does the right thing.
> 
> The idea is that the default is to *not* bootstrap the compiler, if the
> system compiler is new enough.  E.g. if you build r350256 from a system
> built before r350256, it will normally automatically bootstrap
> everything.
> 
> E.g., your previous builds did not have to bootstrap, and now they do,
> which is why they take longer.
> 
> So the only good way to compare is to force MK_SYSTEM_COMPILER=yes and
> MK_SYSTEM_LINKER=yes, so both buildworlds will do the same thing.
> 
> I did a few tests on a relatively fast machine, and buildworld with
> those settings on took approximately the same time at r350255 and
> r350256.  I'm now repeating those experiments to feed the results to
> ministat.

Repeating buildworld 3 times for r350255 and r350256 (with both
MK_SYSTEM_COMPILER and MK_SYSTEM_LINKER set to "yes") shows no
difference in measured real time, according to ministat:

$ head real-*.txt
==> real-r350255.txt <==
1562.12
1587.61
1582.78

==> real-r350256.txt <==
1574.50
1559.20
1584.50

$ ministat real-*.txt
x real-r350255.txt
+ real-r350256.txt
+------------------------------------------------------------------------------+
|+      x                             +                   x   +       x        |
|  |_________|____________________A___M______A____________M______|____________||
+------------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x   3       1562.12       1587.61       1582.78     1577.5033     13.539477
+   3        1559.2        1584.5        1574.5     1572.7333     12.742187
No difference proven at 95.0% confidence

-Dimitry

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