RFR: Don't treat allocation regions implicitely live during traversal GC

[Roman Kennke]

Am 31.01.2018 um 21:15 schrieb Aleksey Shipilev:
> On 01/31/2018 09:03 PM, Aleksey Shipilev wrote:
>> On 01/31/2018 08:59 PM, Roman Kennke wrote:
>>> Until now, we treated allocation regions from between GC cycles all live in traversal GC. This seems
>>> inconsequential: we are not treating alloc regions live during the cycle. This means that all the
>>> allocated garbage will have to pass through one complete cycle to count its liveness, and then
>>> another cycle to clear it up. This patch changes this to traverse+clear alloc regions in the next
>>> cycle.
>>>
>>> This gives some application a huge boost. E.g. compiler.compiler goes from 180ops/m to around
>>> 205ops/m in my tests.
>>>
>>> http://cr.openjdk.java.net/~rkennke/better-traversal-heuristics/webrev.00/
>>
>> Um. Doesn't it break non-Traversal GCs? Shared/TLAB allocs would not be counted as live with e.g.
>> "adaptive"?
> 
> Yes, it does break half of hotspot_gc_shenandoah. Should be e.g.:
> 
> bool ShenandoahFreeSet::implicit_live(ShenandoahHeap::AllocType type) const {
>    ShenandoahHeap* heap = ShenandoahHeap::heap();
>    if (heap->shenandoahPolicy()->can_do_traversal_gc()) {
>      if (heap->is_concurrent_traversal_in_progress()) {
>        return false;
>      }
>      switch (type) {
>        case ShenandoahHeap::_alloc_tlab:
>        case ShenandoahHeap::_alloc_shared:
>          return false;
>        case ShenandoahHeap::_alloc_gclab:
>        case ShenandoahHeap::_alloc_shared_gc:
>          return true;
>        default:
>          ShouldNotReachHere();
>      }
>    }
>    return true;
> }
> 
> -Aleksey
> 


This seems even better. I'm going to push this then?

http://cr.openjdk.java.net/~rkennke/better-traversal-heuristics/webrev.02/

Good?

Roman