RFR: Better handling of cancelled_gc

[Zhengyu Gu]

I am not sure I agree with OrderAccess change. I don't think release_store/load_acquire semantic
applies here...


Besides, if cancel_congc happens rarely, a full fence is not that bad. A barrier in checking code,
which executes at much higher rate, may not yield any benefit.

Thanks,

-Zhengyu





On 11/09/2016 09:20 AM, Roman Kennke wrote:
> This patch:
> - Makes _cancelled_gc volatile and accessed by load_acquire and
> release_store so that observing threads are seeing changes quickly
> instead of checking cached values
> - Improve the concurrent mark loop so that it doesn't check that flag
> on every iteration, but only every 1000th iteration, which should be
> plenty fast enough
>
> http://cr.openjdk.java.net/~rkennke/cancelgc/webrev.01/
>
> OK?
>
> Roman
>