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

[Vladimir Kozlov]

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.