RFR (S): Specialize iteration over marked objects

[Roman Kennke]

Yup!

Have a nice weekend!
Roman


Am Freitag, den 04.11.2016, 22:13 +0100 schrieb Aleksey Shipilev:
> D'oh!
> 
> I actually first tried to construct something like
> ShenandoahMarkObjsClosure<T> that instantiates T implicitly, but then
> I
> gutted the implementation up to the point we could use the templated
> methods instead. Silly me.
> 
> See the update:
> 
> http://cr.openjdk.java.net/~shade/shenandoah/specialize-mark-iterate/
> webrev.02/
> 
> Thanks,
> -Aleksey
> 
> On 11/04/2016 08:36 PM, Roman Kennke wrote:
> > 
> > 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-iter
> > > ate/
> > > webrev.01/
> > > 
> > > After this change, our work is concentrated in specialized
> > > methods,
> > > e.g.:
> > > 
> > >    6.90%  ShenandoahMarkObjsClosure<ShenandoahMarkUpdateRefsClosu
> > > re,
> > > 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
> > > 
> > > 
>