RFR: 8069273: Decrease Hot Card Cache Lock contention

[Thomas Schatzl]

Hi,

On Tue, 2015-01-27 at 11:32 +0100, Claes Redestad wrote:
> Hi again,
> 
> new webrev: http://cr.openjdk.java.net/~redestad/8069273/webrev.04/
> 
> This version fixes a crash issue in G1HotCardCache::reset_hot_cache when
> G1ConcRSLogCacheSize=0

  it would be nice to add a test case that checks boundary values like
that for this flag.

> G1HotCardCache::hot_cache_is_empty was broken in the same way, but
> since it was unused I've opted to remove it rather than fix it.

It would be nice if G1HotCardCache::initialize() used the reset()
method. Then the initialization code would not need to be duplicated.

The problem are the asserts in the reset() method - either create a
reset_int(), or weaken the asserts by adding a !
Universe::fully_initialized() there.

Looks good otherwise.

Thanks,
  Thomas