RFR: 8180421: Change default value of BiasedLockingStartupDelay to 0

[Claes Redestad]

Hi Robbin,

looks good to me!

While there are some near-regressions in a few startup tests, they are 
not statistically significant. At the same time the peak performance and 
latency benefits on some benchmarks and applications of not delaying is 
clearly measurable, which makes this seem like the right thing to do to me.

/Claes

On 06/26/2017 03:17 PM, Robbin Ehn wrote:
> Hi all, please review.
>
> On behalf of Stefan J, this patch changes the default value of 
> BiasedLockingStartupDelay to 0.
> "The delay is however a problem for the some of the GC algorithms that 
> use the mark-word."
> "Benchmark runs doesn't show any regressions for either startup times 
> or steady state performance when setting it to 0."
>
> CSR: https://bugs.openjdk.java.net/browse/JDK-8181778
> Issue: https://bugs.openjdk.java.net/browse/JDK-8180421
>
> Thanks!
>
> /Robbin
>
> diff -r 26a2358e2796 src/share/vm/runtime/globals.hpp
> --- a/src/share/vm/runtime/globals.hpp    Fri Jun 23 15:16:23 2017 -0700
> +++ b/src/share/vm/runtime/globals.hpp    Mon Jun 26 15:03:34 2017 +0200
> @@ -1307,1 +1307,1 @@
> -  product(intx, BiasedLockingStartupDelay, 
> 4000,                            \
> +  product(intx, BiasedLockingStartupDelay, 
> 0,                               \