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comparison src/share/vm/memory/universe.cpp @ 13000:209aa13ab8c0

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8024927: Nashorn performance regression with CompressedOops Summary: 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
author coleenp
date Fri, 25 Oct 2013 15:19:29 -0400
parents a6177f601c64
children 610be0309a79 2b8e28fdf503
comparison
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12999:634715d59d9e 13000:209aa13ab8c0
675 // ZeroBased - Use zero based compressed oops with encoding when 675 // ZeroBased - Use zero based compressed oops with encoding when
676 // NarrowOopHeapBaseMin + heap_size < 32Gb 676 // NarrowOopHeapBaseMin + heap_size < 32Gb
677 // HeapBased - Use compressed oops with heap base + encoding. 677 // HeapBased - Use compressed oops with heap base + encoding.
678 678
679 // 4Gb 679 // 4Gb
680 static const uint64_t NarrowOopHeapMax = (uint64_t(max_juint) + 1); 680 static const uint64_t UnscaledOopHeapMax = (uint64_t(max_juint) + 1);
681 // 32Gb 681 // 32Gb
682 // OopEncodingHeapMax == NarrowOopHeapMax << LogMinObjAlignmentInBytes; 682 // OopEncodingHeapMax == UnscaledOopHeapMax << LogMinObjAlignmentInBytes;
683 683
684 char* Universe::preferred_heap_base(size_t heap_size, size_t alignment, NARROW_OOP_MODE mode) { 684 char* Universe::preferred_heap_base(size_t heap_size, size_t alignment, NARROW_OOP_MODE mode) {
685 assert(is_size_aligned((size_t)OopEncodingHeapMax, alignment), "Must be"); 685 assert(is_size_aligned((size_t)OopEncodingHeapMax, alignment), "Must be");
686 assert(is_size_aligned((size_t)NarrowOopHeapMax, alignment), "Must be"); 686 assert(is_size_aligned((size_t)UnscaledOopHeapMax, alignment), "Must be");
687 assert(is_size_aligned(heap_size, alignment), "Must be"); 687 assert(is_size_aligned(heap_size, alignment), "Must be");
688 688
689 uintx heap_base_min_address_aligned = align_size_up(HeapBaseMinAddress, alignment); 689 uintx heap_base_min_address_aligned = align_size_up(HeapBaseMinAddress, alignment);
690 690
691 size_t base = 0; 691 size_t base = 0;
700 base = heap_base_min_address_aligned; 700 base = heap_base_min_address_aligned;
701 701
702 // If the total size is small enough to allow UnscaledNarrowOop then 702 // If the total size is small enough to allow UnscaledNarrowOop then
703 // just use UnscaledNarrowOop. 703 // just use UnscaledNarrowOop.
704 } else if ((total_size <= OopEncodingHeapMax) && (mode != HeapBasedNarrowOop)) { 704 } else if ((total_size <= OopEncodingHeapMax) && (mode != HeapBasedNarrowOop)) {
705 if ((total_size <= NarrowOopHeapMax) && (mode == UnscaledNarrowOop) && 705 if ((total_size <= UnscaledOopHeapMax) && (mode == UnscaledNarrowOop) &&
706 (Universe::narrow_oop_shift() == 0)) { 706 (Universe::narrow_oop_shift() == 0)) {
707 // Use 32-bits oops without encoding and 707 // Use 32-bits oops without encoding and
708 // place heap's top on the 4Gb boundary 708 // place heap's top on the 4Gb boundary
709 base = (NarrowOopHeapMax - heap_size); 709 base = (UnscaledOopHeapMax - heap_size);
710 } else { 710 } else {
711 // Can't reserve with NarrowOopShift == 0 711 // Can't reserve with NarrowOopShift == 0
712 Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes); 712 Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
713
713 if (mode == UnscaledNarrowOop || 714 if (mode == UnscaledNarrowOop ||
714 mode == ZeroBasedNarrowOop && total_size <= NarrowOopHeapMax) { 715 mode == ZeroBasedNarrowOop && total_size <= UnscaledOopHeapMax) {
716
715 // Use zero based compressed oops with encoding and 717 // Use zero based compressed oops with encoding and
716 // place heap's top on the 32Gb boundary in case 718 // place heap's top on the 32Gb boundary in case
717 // total_size > 4Gb or failed to reserve below 4Gb. 719 // total_size > 4Gb or failed to reserve below 4Gb.
718 base = (OopEncodingHeapMax - heap_size); 720 uint64_t heap_top = OopEncodingHeapMax;
721
722 // For small heaps, save some space for compressed class pointer
723 // space so it can be decoded with no base.
724 if (UseCompressedClassPointers && !UseSharedSpaces &&
725 OopEncodingHeapMax <= 32*G) {
726
727 uint64_t class_space = align_size_up(CompressedClassSpaceSize, alignment);
728 assert(is_size_aligned((size_t)OopEncodingHeapMax-class_space,
729 alignment), "difference must be aligned too");
730 uint64_t new_top = OopEncodingHeapMax-class_space;
731
732 if (total_size <= new_top) {
733 heap_top = new_top;
734 }
735 }
736
737 // Align base to the adjusted top of the heap
738 base = heap_top - heap_size;
719 } 739 }
720 } 740 }
721 } else { 741 } else {
722 // UnscaledNarrowOop encoding didn't work, and no base was found for ZeroBasedOops or 742 // UnscaledNarrowOop encoding didn't work, and no base was found for ZeroBasedOops or
723 // HeapBasedNarrowOop encoding was requested. So, can't reserve below 32Gb. 743 // HeapBasedNarrowOop encoding was requested. So, can't reserve below 32Gb.
735 Universe::set_narrow_oop_use_implicit_null_checks(true); 755 Universe::set_narrow_oop_use_implicit_null_checks(true);
736 } else { 756 } else {
737 // Set to a non-NULL value so the ReservedSpace ctor computes 757 // Set to a non-NULL value so the ReservedSpace ctor computes
738 // the correct no-access prefix. 758 // the correct no-access prefix.
739 // The final value will be set in initialize_heap() below. 759 // The final value will be set in initialize_heap() below.
740 Universe::set_narrow_oop_base((address)NarrowOopHeapMax); 760 Universe::set_narrow_oop_base((address)UnscaledOopHeapMax);
741 #ifdef _WIN64 761 #ifdef _WIN64
742 if (UseLargePages) { 762 if (UseLargePages) {
743 // Cannot allocate guard pages for implicit checks in indexed 763 // Cannot allocate guard pages for implicit checks in indexed
744 // addressing mode when large pages are specified on windows. 764 // addressing mode when large pages are specified on windows.
745 Universe::set_narrow_oop_use_implicit_null_checks(false); 765 Universe::set_narrow_oop_use_implicit_null_checks(false);
831 // Don't need guard page for implicit checks in indexed addressing 851 // Don't need guard page for implicit checks in indexed addressing
832 // mode with zero based Compressed Oops. 852 // mode with zero based Compressed Oops.
833 Universe::set_narrow_oop_use_implicit_null_checks(true); 853 Universe::set_narrow_oop_use_implicit_null_checks(true);
834 } 854 }
835 #endif // _WIN64 855 #endif // _WIN64
836 if((uint64_t)Universe::heap()->reserved_region().end() > NarrowOopHeapMax) { 856 if((uint64_t)Universe::heap()->reserved_region().end() > UnscaledOopHeapMax) {
837 // Can't reserve heap below 4Gb. 857 // Can't reserve heap below 4Gb.
838 Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes); 858 Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
839 } else { 859 } else {
840 Universe::set_narrow_oop_shift(0); 860 Universe::set_narrow_oop_shift(0);
841 if (verbose) { 861 if (verbose) {