RFR: 8198225: os::attempt_reserve_memory_at records memory as committed

[Stefan Karlsson]

Hi all,

Please review this small patch to fix the NMT memory tracking for 
os::attempt_reserve_memory_at.

http://cr.openjdk.java.net/~stefank/8198225/webrev.01/
https://bugs.openjdk.java.net/browse/JDK-8198225

This problem could be seen in the NMT output (Note: the fix for 
JDK-8196405 was also applied when this was generated):

Total: reserved=18728431KB, committed=18463315KB
-                 Java Heap (reserved=16437248KB, committed=16437248KB)
                             (mmap: reserved=16437248KB, 
committed=16437248KB)

-                     Class (reserved=1078402KB, committed=1077890KB)

and

[0x00000007c0000000 - 0x0000000800000000] reserved and committed 
1048576KB for Class from
     [0x00002b96ab32655c] ReservedSpace::ReservedSpace(unsigned long, 
unsigned long, bool, char*)+0xac
     [0x00002b96aaea116b] 
Metaspace::allocate_metaspace_compressed_klass_ptrs(char*, unsigned 
char*)+0x15b
     [0x00002b96aaea36bc] Metaspace::global_initialize()+0x24c
     [0x00002b96ab2c589f] universe_init()+0x8f

         [0x00000007c0000000 - 0x00000007c0340000] committed 3328KB from
             [0x00002b96ab31fb35] commit_expanded(char*, unsigned long, 
unsigned long, bool, bool)+0x25
             [0x00002b96ab320d52] VirtualSpace::expand_by(unsigned long, 
bool)+0x342
             [0x00002b96aae9466f] VirtualSpaceNode::expand_by(unsigned 
long, unsigned long)+0x4f
             [0x00002b96aae953b0] 
VirtualSpaceList::expand_node_by(VirtualSpaceNode*, unsigned long, 
unsigned long)+0x40

         [0x00000007c0340000 - 0x0000000800000000] committed 1045248KB from
             [0x00002b96ab32655c] ReservedSpace::ReservedSpace(unsigned 
long, unsigned long, bool, char*)+0xac
             [0x00002b96aaea116b] 
Metaspace::allocate_metaspace_compressed_klass_ptrs(char*, unsigned 
char*)+0x15b
             [0x00002b96aaea36bc] Metaspace::global_initialize()+0x24c
             [0x00002b96ab2c589f] universe_init()+0x8f


After the fix we have:

Total: reserved=18696411KB, committed=13460639KB
-                 Java Heap (reserved=16437248KB, committed=12607488KB)
                             (mmap: reserved=16437248KB, 
committed=12607488KB)

-                     Class (reserved=1078317KB, committed=31149KB)

and

[0x00000007c0000000 - 0x0000000800000000] reserved 1048576KB for Class from
     [0x00002af96c2f66bc] ReservedSpace::ReservedSpace(unsigned long, 
unsigned long, bool, char*)+0xac
     [0x00002af96be7116b] 
Metaspace::allocate_metaspace_compressed_klass_ptrs(char*, unsigned 
char*)+0x15b
     [0x00002af96be736bc] Metaspace::global_initialize()+0x24c
     [0x00002af96c2959ff] universe_init()+0x8f

         [0x00000007c0000000 - 0x00000007c0320000] committed 3200KB from
             [0x00002af96c2efc95] commit_expanded(char*, unsigned long, 
unsigned long, bool, bool)+0x25
             [0x00002af96c2f0eb2] VirtualSpace::expand_by(unsigned long, 
bool)+0x342
             [0x00002af96be6466f] VirtualSpaceNode::expand_by(unsigned 
long, unsigned long)+0x4f
             [0x00002af96be653b0] 
VirtualSpaceList::expand_node_by(VirtualSpaceNode*, unsigned long, 
unsigned long)+0x40


I tested this with the new jtreg test and by manual inspection of the 
NMT output.

Thanks,
StefanK