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8153340: Disallow misconfiguration and improve the consistency of allocation prefetching

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Improve allocation prefetching.

Reviewed-by: kvn
This commit is contained in:
Zoltan Majo 2016-04-29 08:32:42 +02:00
parent 3a358f4cff
commit 413417522f
11 changed files with 73 additions and 104 deletions
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18
hotspot/src/share/vm/gc/shared/threadLocalAllocBuffer.cpp
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@ -36,6 +36,7 @@
// static member initialization
size_t ThreadLocalAllocBuffer::_max_size = 0;
int ThreadLocalAllocBuffer::_reserve_for_allocation_prefetch = 0;
unsigned ThreadLocalAllocBuffer::_target_refills = 0;
GlobalTLABStats* ThreadLocalAllocBuffer::_global_stats = NULL;
@ -215,6 +216,23 @@ void ThreadLocalAllocBuffer::startup_initialization() {
_global_stats = new GlobalTLABStats();
// Need extra space at the end of TLAB, otherwise prefetching
// instructions will fault (due to accessing memory outside of heap).
// The amount of space is the max of the number of lines to
// prefetch for array and for instance allocations. (Extra space must be
// reserved to accommodate both types of allocations.)
//
// Only SPARC-specific BIS instructions are known to fault. (Those
// instructions are generated if AllocatePrefetchStyle==3 and
// AllocatePrefetchInstr==1). To be on the safe side, however,
// extra space is reserved for all combinations of
// AllocatePrefetchStyle and AllocatePrefetchInstr.
// +1 for rounding up to next cache line, +1 to be safe
int lines = MAX2(AllocatePrefetchLines, AllocateInstancePrefetchLines) + 2;
_reserve_for_allocation_prefetch = (AllocatePrefetchDistance + AllocatePrefetchStepSize * lines) /
(int)HeapWordSize;
// During jvm startup, the main (primordial) thread is initialized
// before the heap is initialized. So reinitialize it now.
guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread");