Request for code review (M) - 8081629: CMS split_block() does not correctly fix up block-offset-table for large blocks

[Jon Masamitsu]

This bug is causing large young GC times for ParNew when
there are large objects in the heap and the logarithmic strides
are being used (badly).

https://bugs.openjdk.java.net/browse/JDK-8081629

The change in webrev_min corrects the problem
with the minimum code change (least risk).

http://cr.openjdk.java.net/~jmasa/8081629/webrev_min.02/

A rewriting of split_block() in included in a second webrev

http://cr.openjdk.java.net/~jmasa/8081629/webrev.02/

I've willing to go with the minimum change but could also
be encouraged to push the rewrite of split_block().

Vote for the one you like with your code review.

The diff between webrev_min.02 and webrev.02 is
here but I don't find it that useful.

http://cr.openjdk.java.net/~jmasa/8081629/webrev_delta.02/

Thanks.

Jon