RFR: 8218743: SA: Add support for large bitmaps

[Jini George]

Hi Stefan,

Looks good to me. Nits: pls do change the copyright year.

Thanks,
Jini.

On 2/11/2019 6:06 PM, Stefan Karlsson wrote:
> Hi all,
> 
> Please review this patch to add support for large bitmaps in the SA.
> 
> http://cr.openjdk.java.net/~stefank/8218743/webrev.01/
> https://bugs.openjdk.java.net/browse/JDK-8218743
> 
> I've added a minimal interface (at, atPut, clear) that uses longs 
> instead of ints, and changed MarkBits to use this interface.
> 
> I've implemented a segmented bitmap that, currently, all GCs use when 
> asked for a bitmap in MarkBits. Later ZGC will provide its own 
> discontiguous bitmap, implementing the new interface, but that will be 
> sent out as a separate RFE.
> 
> I've tested this with a temporary patch that lowers the segment size and 
> implements a jtreg test:
> http://cr.openjdk.java.net/~stefank/8218743/webrev.test.01
> 
> I ran through the all the tests in serviceability/sa with both these 
> patches.
> 
> Thanks,
> StefanK