CRR (S): 7046182: G1: remove unnecessary iterations over the collection set

[Bengt Rutisson]

Tony,

Looks good.

Bengt

On 2011-06-13 19:22, Tony Printezis wrote:
> ..and of course the webrev url is wrong. This is the right one:
>
> http://cr.openjdk.java.net/~tonyp/7046182/webrev.0/
>
> Apologies!
>
> Tony
>
> Tony Printezis wrote:
>> Hi all,
>>
>> Could I have a couple of code reviews for this change?
>>
>> http://syros.us.oracle.com/local_ws/hotspot-g1-cset-iter/webrev/
>>
>> Basically, we (unnecessarily) iterate over the collection set a 
>> couple of times during each GC to reset two fields on the RSet data 
>> structure. It's better to make sure that those fields are reset when 
>> the region is freed (so it's "ready to go" when it's re-allocated) to 
>> avoid those two iterations.
>>
>> I added some extra code to assert that these two fields are in the 
>> correct state before each GC and I also added an extra verification 
>> step on the master free list to also check that condition on all the 
>> regions on it (since the two fields in question should be reset 
>> before the region is added to the master free list).
>>
>> I'm piggy-backing the removal of the G1_REM_SET_LOGGING code on this 
>> (it's kinda related as it also iterates over the collection set - so, 
>> we remove more collection set iterations!). We haven't used it for a 
>> while and it's helpfulness is marginal.
>>
>> Thanks,
>>
>> Tony
>>