RFR: Enable fast synchronizer root scanning by default

[Roman Kennke]

Am 11.05.2017 um 11:14 schrieb Aleksey Shipilev:
> Hi,
>
> We see good performance improvements, and positive code reviews upstream for
> fast synchronizer root scanning. Let's enable it by default:
>
> $ hg diff
> diff -r 85c3e4589c8e src/share/vm/gc/shenandoah/shenandoah_globals.hpp
> --- a/src/share/vm/gc/shenandoah/shenandoah_globals.hpp	Wed May 10 22:23:37 2017
> +0200
> +++ b/src/share/vm/gc/shenandoah/shenandoah_globals.hpp	Thu May 11 11:00:49 2017
> +0200
> @@ -214,7 +214,7 @@
>            "If true, only execute storeval barrier when updating "           \
>            "references.")                                                    \
>                                                                              \
> -  experimental(bool, ShenandoahFastSyncRoots, false,                        \
> +  experimental(bool, ShenandoahFastSyncRoots, true,                         \
>            "Enable fast synchronizer roots scanning")                        \
>                                                                              \
>    diagnostic(bool, ShenandoahSATBBarrier, true,                             \
>
>
> Testing: hotspot_gc_shenandoah
>
> Thanks,
> -Aleksey
>
Ok