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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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45
hotspot/src/cpu/sparc/vm/vm_version_sparc.cpp
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@ -49,9 +49,11 @@ void VM_Version::initialize() {
AllocatePrefetchDistance = allocate_prefetch_distance();
AllocatePrefetchStyle = allocate_prefetch_style();
if (AllocatePrefetchStyle == 3 && !has_blk_init()) {
warning("BIS instructions are not available on this CPU");
FLAG_SET_DEFAULT(AllocatePrefetchStyle, 1);
if (!has_blk_init()) {
if (AllocatePrefetchInstr == 1) {
warning("BIS instructions required for AllocatePrefetchInstr 1 unavailable");
FLAG_SET_DEFAULT(AllocatePrefetchInstr, 0);
}
}
UseSSE = 0; // Only on x86 and x64
@ -88,11 +90,13 @@ void VM_Version::initialize() {
if (has_blk_init() && UseTLAB &&
FLAG_IS_DEFAULT(AllocatePrefetchInstr)) {
// Use BIS instruction for TLAB allocation prefetch.
FLAG_SET_ERGO(intx, AllocatePrefetchInstr, 1);
if (FLAG_IS_DEFAULT(AllocatePrefetchStyle)) {
FLAG_SET_ERGO(intx, AllocatePrefetchStyle, 3);
}
if (FLAG_IS_DEFAULT(AllocatePrefetchDistance)) {
FLAG_SET_DEFAULT(AllocatePrefetchInstr, 1);
}
if (FLAG_IS_DEFAULT(AllocatePrefetchDistance)) {
if (AllocatePrefetchInstr == 0) {
// Use different prefetch distance without BIS
FLAG_SET_DEFAULT(AllocatePrefetchDistance, 256);
} else {
// Use smaller prefetch distance with BIS
FLAG_SET_DEFAULT(AllocatePrefetchDistance, 64);
}
@ -107,25 +111,14 @@ void VM_Version::initialize() {
FLAG_SET_ERGO(intx, AllocateInstancePrefetchLines, AllocateInstancePrefetchLines*2);
}
}
if (AllocatePrefetchStyle != 3 && FLAG_IS_DEFAULT(AllocatePrefetchDistance)) {
// Use different prefetch distance without BIS
FLAG_SET_DEFAULT(AllocatePrefetchDistance, 256);
}
if (AllocatePrefetchInstr == 1) {
// Need extra space at the end of TLAB for BIS, 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 accomodate both types of allocations.)
// +1 for rounding up to next cache line, +1 to be safe
int lines = MAX2(AllocatePrefetchLines, AllocateInstancePrefetchLines) + 2;
int step_size = AllocatePrefetchStepSize;
int distance = AllocatePrefetchDistance;
_reserve_for_allocation_prefetch = (distance + step_size*lines)/(int)HeapWordSize;
}
}
#endif
if (AllocatePrefetchInstr == 1) {
// Use allocation prefetch style 3 because BIS instructions
// require aligned memory addresses.
FLAG_SET_DEFAULT(AllocatePrefetchStyle, 3);
}
#endif /* COMPILER2 */
}
// Use hardware population count instruction if available.