[OE-core] Some further build dependency timings

[Richard Purdie]

On Wed, 2011-10-12 at 15:49 +0100, Richard Purdie wrote:
> On Wed, 2011-10-12 at 09:40 -0500, Mark Hatle wrote:
> > It would be interesting to determine first off, if there is anywhere pseudo
> > should be running that it currently isn't.  And second if this is simply due to
> > LD_PRELOAD time, or if enabling the jump table is the culprit.
> > 
> > One potential optimization, when PSEUDO_DISABLE=1 is to only setup the jump
> > table entries for fork/exec items.
> 
> Agreed, I don't know where the time is being spent exactly at this
> point. I do know we execute an absolute ton of exec/fork calls so
> removing any overhead from them will improve our speed though. This
> change means do_configure won't run with pseudo enabled for example
> which is a very exec heavy task. 

So we did some tests, I thought I'd share the results:

base build config:

real	38m12.356s
user	236m4.710s
sys	39m38.180s

adding in the psuedo patches but not enabling (effectively jitter
measurement):

real	38m13.034s
user	235m44.250s
sys	39m6.150s

enabling the lazy linking:

real	38m16.121s
user	236m1.300s
sys	39m45.860s

Enable PSEUDO_UNLOAD:

real	35m46.281s
user	233m56.750s
sys	37m51.400s

So the big win isn't the linking, its the unloading of pseudo when we
don't need it...

Cheers,

Richard