Request for review: 7052429: G1: Avoid unnecessary scanning of humongous regions during concurrent marking

[John Cuthbertson]

Hi Tao,

Changes look good. It might be a good idea to add an assert after you 
look up the heap region:

assert(!hr->isHumongous() || mr.start() == hr->bottom(), "...");

so that, if the region is humongous, we verify that the start of memory 
region is the base of the heap region.

Thanks,

JohnC

On 2/1/2013 6:37 PM, Tao Mao wrote:
> 7052429: G1: Avoid unnecessary scanning of humongous regions during 
> concurrent marking
> https://jbs.oracle.com/bugs/browse/JDK-7052429
>
> webrev:
> http://cr.openjdk.java.net/~tamao/7052429/webrev.00/
>
> changeset:
> Avoid wasted work of _nextMarkBitMap->iterate() when the current 
> region is a humongous region and the first bit is NOT marked, whereas 
> the case where a humonguous region with its first bit marked is 
> properly handled in iterate() routine.