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

[Stefan Karlsson]

Hi Thomas,

On 2018-02-15 18:32, Thomas Stüfe wrote:
> Hi Stefan,
>
> looks good to me too. Thanks for fixing this.

Thanks!

>
> Small note, though not part of your test: I find the version of 
> "attempt_reserve_memory_at()" which takes a file handle to be 
> misleadingly named - it maps a file to a specific location, the result 
> is committed memory, not reserved memory.

Yes, I agree. We have similar issues with large pages that gets 
committed when they are reserved.

StefanK

>
> Best Regards, Thomas
>
>
> On Thu, Feb 15, 2018 at 4:19 PM, Stefan Karlsson 
> <stefan.karlsson at oracle.com <mailto:stefan.karlsson at oracle.com>> wrote:
>
>     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/
>     <http://cr.openjdk.java.net/%7Estefank/8198225/webrev.01/>
>     https://bugs.openjdk.java.net/browse/JDK-8198225
>     <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
>
>