Request for reviews (M): 7017124: VM statistic use 32-bit values which may overflow

Vladimir Kozlov vladimir.kozlov at oracle.com
Thu Feb 3 16:05:13 PST 2011


I am investigating native memory usage with EA and saw these problems.

http://cr.openjdk.java.net/~kvn/7017124/webrev

Fixed 7017124: VM statistic use 32-bit values which may overflow

During long enough time (tens minutes) on modern processors
some VM statistic 32-bit values overflow. We need to use longs.
And when a value is long we still have a problem since it is
incremented not atomically in 32-bit VM.

Added new Atomic method inc_counter() to increment long values,
it is not precise on MP (lock is not used) but it is fine.

Fixed several output formats to use VM FORMAT macros.

I have to remove v9 check assert from Atomic_move_long() since
it is called before VM_Version is initialized and C2 is built
for v9 only anyway.

Removed unused Chunk::clean_chunk_pool().

I fixed only statistic which was interesting to me.


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