[9] RFR (L): 8015774: Add support for multiple code heaps

[Vladimir Kozlov]

For the record, SegmentedCodeCache is enabled by default when 
TieredCompilation is enabled and ReservedCodeCacheSize >= 240 MB. 
Otherwise it is false by default.

arguments.cpp - in set_tiered_flags() swap SegmentedCodeCache setting 
and segments size adjustment - do adjustment only if SegmentedCodeCache 
is enabled. Also I think each flag should be checked and adjusted 
separately. You may bail out (vm_exit_during_initialization) if sizes do 
not add up. And use

Align second line:

2461   } else if ((!FLAG_IS_DEFAULT(NonMethodCodeHeapSize) || 
!FLAG_IS_DEFAULT(ProfiledCodeHeapSize) || 
!FLAG_IS_DEFAULT(NonProfiledCodeHeapSize))
2462       && (NonMethodCodeHeapSize + NonProfiledCodeHeapSize + 
ProfiledCodeHeapSize) != ReservedCodeCacheSize) {

codeCache.cpp - in initialize_heaps() add new methods in C1 and C2 to 
return buffer_size they need. Add assert(SegmentedCodeCache) to this 
method to show that we call it only in such case.  You do adjustment 
only when all flags are default. But you still need to check that you 
have space in NonMethodCodeHeap for scratch buffers.

codeCache.hpp - comment alignment:
+     // Creates a new heap with the given name and size, containing 
CodeBlobs of the given type
!   static void add_heap(ReservedSpace rs, const char* name, size_t 
size_initial, int code_blob_type);

nmethod.cpp - in new() can we mark nmethod allocation critical only when 
SegmentedCodeCache is enabled?

Thanks,
Vladimir

On 8/28/14 5:09 AM, Tobias Hartmann wrote:
> Hi,
>
> the segmented code cache JEP is now targeted. Please review the final
> implementation before integration. The previous RFR, including a short
> description, can be found here [1].
>
> JEP: https://bugs.openjdk.java.net/browse/JDK-8043304
> Bug: https://bugs.openjdk.java.net/browse/JDK-8015774
> Implementation: http://cr.openjdk.java.net/~thartmann/8015774/webrev.03/
> JDK-Test fix:
> http://cr.openjdk.java.net/~thartmann/8015774_jdk_test/webrev.00/
>
> Changes since the last review:
> - Merged with other changes (for example, G1 class unloading changes [2])
> - Fixed some minor bugs that showed up during testing
> - Refactoring of 'NMethodIterator' and CodeCache implementation
> - Non-method CodeHeap size increased to 5 MB
> - Fallback solution: Store non-method code in the non-profiled code heap
> if there is not enough space in the non-method code heap (see
> 'CodeCache::allocate')
>
> Additional testing:
> - BigApps (Weblogic, Dacapo, runThese, Kitchensink)
> - Compiler and GC nightlies
> - jtreg tests
> - VM (NSK) Testbase
> - More performance testing (results attached to the bug)
>
> Thanks,
> Tobias
>
> [1]
> http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2014-April/014098.html
>
> [2] https://bugs.openjdk.java.net/browse/JDK-8049421