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8024927: Nashorn performance regression with CompressedOops

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Allocate compressed class space at end of Java heap.  For small heap sizes, without CDS, save some space so compressed classes can have the same favorable compression as oops

Reviewed-by: stefank, hseigel, goetz
This commit is contained in:
Coleen Phillimore 2013-10-25 15:19:29 -04:00
parent 4e192289d4
commit 3e6630c07b
8 changed files with 295 additions and 95 deletions
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38
hotspot/src/share/vm/memory/universe.cpp
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@ -677,13 +677,13 @@ jint universe_init() {
// HeapBased - Use compressed oops with heap base + encoding.
// 4Gb
static const uint64_t NarrowOopHeapMax = (uint64_t(max_juint) + 1);
static const uint64_t UnscaledOopHeapMax = (uint64_t(max_juint) + 1);
// 32Gb
// OopEncodingHeapMax == NarrowOopHeapMax << LogMinObjAlignmentInBytes;
// OopEncodingHeapMax == UnscaledOopHeapMax << LogMinObjAlignmentInBytes;
char* Universe::preferred_heap_base(size_t heap_size, size_t alignment, NARROW_OOP_MODE mode) {
assert(is_size_aligned((size_t)OopEncodingHeapMax, alignment), "Must be");
assert(is_size_aligned((size_t)NarrowOopHeapMax, alignment), "Must be");
assert(is_size_aligned((size_t)UnscaledOopHeapMax, alignment), "Must be");
assert(is_size_aligned(heap_size, alignment), "Must be");
uintx heap_base_min_address_aligned = align_size_up(HeapBaseMinAddress, alignment);
@ -702,20 +702,40 @@ char* Universe::preferred_heap_base(size_t heap_size, size_t alignment, NARROW_O
// If the total size is small enough to allow UnscaledNarrowOop then
// just use UnscaledNarrowOop.
} else if ((total_size <= OopEncodingHeapMax) && (mode != HeapBasedNarrowOop)) {
if ((total_size <= NarrowOopHeapMax) && (mode == UnscaledNarrowOop) &&
if ((total_size <= UnscaledOopHeapMax) && (mode == UnscaledNarrowOop) &&
(Universe::narrow_oop_shift() == 0)) {
// Use 32-bits oops without encoding and
// place heap's top on the 4Gb boundary
base = (NarrowOopHeapMax - heap_size);
base = (UnscaledOopHeapMax - heap_size);
} else {
// Can't reserve with NarrowOopShift == 0
Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
if (mode == UnscaledNarrowOop ||
mode == ZeroBasedNarrowOop && total_size <= NarrowOopHeapMax) {
mode == ZeroBasedNarrowOop && total_size <= UnscaledOopHeapMax) {
// Use zero based compressed oops with encoding and
// place heap's top on the 32Gb boundary in case
// total_size > 4Gb or failed to reserve below 4Gb.
base = (OopEncodingHeapMax - heap_size);
uint64_t heap_top = OopEncodingHeapMax;
// For small heaps, save some space for compressed class pointer
// space so it can be decoded with no base.
if (UseCompressedClassPointers && !UseSharedSpaces &&
OopEncodingHeapMax <= 32*G) {
uint64_t class_space = align_size_up(CompressedClassSpaceSize, alignment);
assert(is_size_aligned((size_t)OopEncodingHeapMax-class_space,
alignment), "difference must be aligned too");
uint64_t new_top = OopEncodingHeapMax-class_space;
if (total_size <= new_top) {
heap_top = new_top;
}
}
// Align base to the adjusted top of the heap
base = heap_top - heap_size;
}
}
} else {
@ -737,7 +757,7 @@ char* Universe::preferred_heap_base(size_t heap_size, size_t alignment, NARROW_O
// Set to a non-NULL value so the ReservedSpace ctor computes
// the correct no-access prefix.
// The final value will be set in initialize_heap() below.
Universe::set_narrow_oop_base((address)NarrowOopHeapMax);
Universe::set_narrow_oop_base((address)UnscaledOopHeapMax);
#ifdef _WIN64
if (UseLargePages) {
// Cannot allocate guard pages for implicit checks in indexed
@ -833,7 +853,7 @@ jint Universe::initialize_heap() {
Universe::set_narrow_oop_use_implicit_null_checks(true);
}
#endif // _WIN64
if((uint64_t)Universe::heap()->reserved_region().end() > NarrowOopHeapMax) {
if((uint64_t)Universe::heap()->reserved_region().end() > UnscaledOopHeapMax) {
// Can't reserve heap below 4Gb.
Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
} else {