Request for reviews (S): 7014874: Incorrect COOPs modes on solaris-{sparcv9, amd64} with ParallelGC

[Vladimir Kozlov]

As Igor explained me only Parallel GC requires boundary
page size alignment due to UseAdaptiveGCBoundary feature.

Vladimir

Y. S. Ramakrishna wrote:
> May be you need a "partition_aligned()" method that
> takes an aligned whole and produces aligned partitions
> thereof given a desired_partitioning request. It would
> seem as though similar logic would need to apply to
> other kinds of heaps... or do they do the right thing
> already? OK, i suppose i should go look, since i am
> supposed to be reviewing, not interviewing ;-)
> 
> -- ramki
> 
> On 01/27/11 14:49, Vladimir Kozlov wrote:
>> Before rounding YG+OG == total heap size. To keep the same
>> total size I need to round one size up and the other down.
>> I still may not preserver the same total size if it is not
>> rounded to the same or large alignment. But it is fine.
>>
>> I already fixed PG rounding before in 6984368 changes:
>>
>> src/share/vm/memory/collectorPolicy.cpp    Tue Sep 14 17:19:35 2010 -0700
>> @@ -32,7 +32,11 @@
>>      MaxPermSize = PermSize;
>>    }
>>    PermSize = MAX2(min_alignment(), align_size_down_(PermSize, 
>> min_alignment()));
>> -  MaxPermSize = align_size_up(MaxPermSize, max_alignment());
>> +  // Don't increase Perm size limit above specified.
>> +  MaxPermSize = align_size_down(MaxPermSize, max_alignment());
>> +  if (PermSize > MaxPermSize) {
>> +    PermSize = MaxPermSize;
>> +  }
>>
>> Vladimir
>>
>> Y. S. Ramakrishna wrote:
>>> I don't understand the logic of the patch. Or rather, i do,
>>> but i question if it is complete: why didn't you also align
>>> the max size of YG and PG down in like manner? I think you
>>> should or you would be open to the same issues, no?
>>>
>>> In fact, it seems as though, as a matter of uniform policy, all min's
>>> should align upwards and all max's align downwards wherever 
>>> (page-)alignment
>>> is sought.
>>>
>>> -- ramki
>>>
>>>
>>> On 01/27/11 14:18, Vladimir Kozlov wrote:
>>>> http://cr.openjdk.java.net/~kvn/7014874/webrev
>>>>
>>>> Fixed 7014874: Incorrect COOPs modes on solaris-{sparcv9,amd64} with 
>>>> ParallelGC
>>>>
>>>> scale_by_NewRatio_aligned() aligns boundary between old
>>>> and young gens to min_alignment() (64K). But code in
>>>> ParallelScavengeHeap::initialize() aligns up both old and
>>>> young gen sizes to large page size.
>>>> As result total heap size could be increased by one large
>>>> page and cross 4gb boundary preventing usage of 32-bit COOPs.
>>>>
>>>> Align old gen size down to keep specified heap size but
>>>> not less than its old gen min size.