RFR (S): Specialize iteration over marked objects

[Roman Kennke]

To be honest, it looks a bit overcomplicated to me :-)

I would think it's enough to make marked_object_iterate() templated:

template <class T>
 void marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {
  ...
  cl->do_object(obj);
  ..
}

and moved to shenandoahHeap.inline.hpp

Moving into ShenandoahHeapRegion is ok too, of course.

Or maybe I'm missing something?
Roman


Am Freitag, den 04.11.2016, 20:01 +0100 schrieb Aleksey Shipilev:
> Hi,
> 
> Our current ShenandoahHeap::marked_object_iterate does the virtual
> call
> to ObjectClosure::do_object for every marked object, for every task
> out
> there. When the per-oop work is small, this is not good. Also limits
> optimizeability (e.g. coalescing ShenandoahHeap::heap(), oopDesc::*,
> etc).
> 
> This is the template-based specialization:
> 
> http://cr.openjdk.java.net/~shade/shenandoah/specialize-mark-iterate/
> webrev.01/
> 
> After this change, our work is concentrated in specialized methods,
> e.g.:
> 
>    6.90%  ShenandoahMarkObjsClosure<ShenandoahMarkUpdateRefsClosure,
> false>::do_object_or_array
>    5.82%  ShenandoahCompactObjectsTask::work
>    5.51%  ShenandoahPrepareForCompactionTask::work
>    5.20%  ShenandoahAdjustPointersClosure::do_oop
>    4.20%  ShenandoahAdjustPointersTask::work
>    ...
> 
> (for ShenandoahAdjustPointersClosure::do_oop, inlining breaks
> elsewhere,
> to be handled separately)
> 
> Testing: hotspot_gc_shenandoah, jcstress -m quick, some
> microbenchmarks
> 
> Thanks,
> -Aleksey
> 
>