RFR: No need for fence in control loop: flags are now ShSharedVariables

[Roman Kennke]

Am 07.03.2018 um 11:16 schrieb Aleksey Shipilev:
> Obvious micro-optimization: we used to have the naked flags that required barriers. Now we use
> ShSharedVariables for storing those flags, and barrier is not needed:
> 
> diff -r 67db05fbda9f src/hotspot/share/gc/shenandoah/shenandoahConcurrentThread.cpp
> --- a/src/hotspot/share/gc/shenandoah/shenandoahConcurrentThread.cpp	Tue Mar 06 22:00:49 2018 +0100
> +++ b/src/hotspot/share/gc/shenandoah/shenandoahConcurrentThread.cpp	Wed Mar 07 11:15:21 2018 +0100
> @@ -195,9 +195,6 @@
> 
>      // Wait before performing the next action
>      os::naked_short_sleep(ShenandoahControlLoopInterval);
> -
> -    // Make sure the _do_full_gc flag changes are seen.
> -    OrderAccess::storeload();
>    }
> 
>    // Wait for the actual stop(), can't leave run_service() earlier.
> 
> 
> Testing: hotspot_gc_shenandoah
> 
> Thanks,
> -Aleksey
> 

Yep.