8.0 performance issue when running build.sh?

[Martin Husemann <martin%duskware.de@localhost>]

I have no scientific data yet, but just noticed that build times on the
auto build cluster did rise very dramatically since it has been updated
to run NetBSD 8.0 RC2.

Since builds move around build slaves sometimes (not exactly randomly,
but anyway) I picked the alpha port as an example (the first few
architectures in the alphabetical list get build slaves assigned pretty
consistently).

This are all successfull builds of HEAD for alpha that happened after June 1:

Build            Slave Seconds
HEAD:201806011030Z b43 3807
HEAD:201806020940Z b43 3785
HEAD:201806021830Z b43 3797
HEAD:201806040210Z b43 3814
HEAD:201806050210Z b43 3814
HEAD:201806050840Z b43 3766
HEAD:201806052050Z b43 3835
HEAD:201806060330Z b43 3817
HEAD:201806061300Z b43 3771
HEAD:201806062340Z b43 3825
HEAD:201806071500Z b43 3780
HEAD:201806081600Z b43 3800
HEAD:201806090120Z b43 3814
HEAD:201806091820Z b43 3816
HEAD:201806100640Z b43 3803
HEAD:201806101910Z b43 3806
HEAD:201806110430Z b43 3814
HEAD:201806112100Z b43 3822
HEAD:201806120750Z b43 3770
HEAD:201806122120Z b43 3817
HEAD:201806130400Z b43 3794
HEAD:201806131340Z b43 3820
HEAD:201806140020Z b43 3803
HEAD:201806151330Z b43 3806
HEAD:201806152250Z b43 3817
HEAD:201806161530Z b43 3810
HEAD:201806170310Z b43 3826
HEAD:201806171540Z b43 3788
HEAD:201806180110Z b43 3794
HEAD:201806181740Z b43 3827
HEAD:201806190430Z b43 3805
HEAD:201806191750Z b43 3763
HEAD:201806200020Z b43 3777
HEAD:201806200950Z b43 3838
HEAD:201806202030Z b43 3815
HEAD:201806211150Z b43 3775
HEAD:201806221250Z b43 3804
HEAD:201806222210Z b43 3840
HEAD:201806231440Z b43 3800
HEAD:201806240250Z b43 3826
HEAD:201806242110Z b43 3797
HEAD:201806250640Z b43 3763
HEAD:201806260450Z b43 3812
HEAD:201806261520Z b43 3801
HEAD:201806270340Z b43 3656
HEAD:201806270810Z b43 3820
HEAD:201806271700Z b43 3763
HEAD:201806280320Z b43 3787
HEAD:201806281810Z b43 3790
HEAD:201806301810Z b43 5583
HEAD:201807012030Z b43 5617
HEAD:201807021930Z b43 5569
HEAD:201807030940Z b43 4246
HEAD:201807031950Z b43 4192
HEAD:201807042110Z b43 4256
HEAD:201807051620Z b43 4212

You will easily guess when the system was upgraded.

Average "alpha" build time was 3800s before and 4811s after the update.

I would not worry a lot about this, as other changes have been made to HEAD
so the things being build are not the same, but overall we see a very similar
pattern even for builds of branches that did not significantly change.

For some reason the netbsd-7* builds seem to be the worst affected, they went
from ~4h to > 12h.


As I said, no scientific data here - but ideas or explanations welcome!

Martin

P.S.: the CPUs are affected by all the recentish issues, we have svs
and fpu_eager enabled, but also mprotect, aslr, ....

P.P.S.: you can see overall build times here:
	http://releng.netbsd.org/cgi-bin/builds.cgi