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src/share/vm/memory/universe.cpp
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rev 7280 : 8064457: Introduce compressed oops mode "disjoint base" and improve compressed heap handling.
@@ -689,107 +689,10 @@
// NarrowOopHeapBaseMin + heap_size < 4Gb
// ZeroBased - Use zero based compressed oops with encoding when
// NarrowOopHeapBaseMin + heap_size < 32Gb
// HeapBased - Use compressed oops with heap base + encoding.
-// 4Gb
-static const uint64_t UnscaledOopHeapMax = (uint64_t(max_juint) + 1);
-// 32Gb
-// 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)UnscaledOopHeapMax, alignment), "Must be");
- assert(is_size_aligned(heap_size, alignment), "Must be");
-
- uintx heap_base_min_address_aligned = align_size_up(HeapBaseMinAddress, alignment);
-
- size_t base = 0;
-#ifdef _LP64
- if (UseCompressedOops) {
- assert(mode == UnscaledNarrowOop ||
- mode == ZeroBasedNarrowOop ||
- mode == HeapBasedNarrowOop, "mode is invalid");
- const size_t total_size = heap_size + heap_base_min_address_aligned;
- // Return specified base for the first request.
- if (!FLAG_IS_DEFAULT(HeapBaseMinAddress) && (mode == UnscaledNarrowOop)) {
- base = heap_base_min_address_aligned;
-
- // If the total size is small enough to allow UnscaledNarrowOop then
- // just use UnscaledNarrowOop.
- } else if ((total_size <= OopEncodingHeapMax) && (mode != HeapBasedNarrowOop)) {
- 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 = (UnscaledOopHeapMax - heap_size);
- } else {
- // Can't reserve with NarrowOopShift == 0
- Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
-
- if (mode == UnscaledNarrowOop ||
- 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.
- 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 {
- // UnscaledNarrowOop encoding didn't work, and no base was found for ZeroBasedOops or
- // HeapBasedNarrowOop encoding was requested. So, can't reserve below 32Gb.
- Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
- }
-
- // Set narrow_oop_base and narrow_oop_use_implicit_null_checks
- // used in ReservedHeapSpace() constructors.
- // The final values will be set in initialize_heap() below.
- if ((base != 0) && ((base + heap_size) <= OopEncodingHeapMax)) {
- // Use zero based compressed oops
- Universe::set_narrow_oop_base(NULL);
- // Don't need guard page for implicit checks in indexed
- // addressing mode with zero based Compressed Oops.
- Universe::set_narrow_oop_use_implicit_null_checks(true);
- } else {
- // 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)UnscaledOopHeapMax);
-#if defined(_WIN64) || defined(AIX)
- if (UseLargePages) {
- // Cannot allocate guard pages for implicit checks in indexed
- // addressing mode when large pages are specified on windows.
- Universe::set_narrow_oop_use_implicit_null_checks(false);
- }
-#endif // _WIN64
- }
- }
-#endif
-
- assert(is_ptr_aligned((char*)base, alignment), "Must be");
- return (char*)base; // also return NULL (don't care) for 32-bit VM
-}
-
jint Universe::initialize_heap() {
if (UseParallelGC) {
#if INCLUDE_ALL_GCS
Universe::_collectedHeap = new ParallelScavengeHeap();
@@ -839,34 +742,17 @@
// This also makes implicit null checking work, because the
// memory+1 page below heap_base needs to cause a signal.
// See needs_explicit_null_check.
// Only set the heap base for compressed oops because it indicates
// compressed oops for pstack code.
- if (((uint64_t)Universe::heap()->reserved_region().end() > OopEncodingHeapMax)) {
- // Can't reserve heap below 32Gb.
- // keep the Universe::narrow_oop_base() set in Universe::reserve_heap()
- Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
-#ifdef AIX
- // There is no protected page before the heap. This assures all oops
- // are decoded so that NULL is preserved, so this page will not be accessed.
- Universe::set_narrow_oop_use_implicit_null_checks(false);
-#endif
- } else {
- Universe::set_narrow_oop_base(0);
-#ifdef _WIN64
- if (!Universe::narrow_oop_use_implicit_null_checks()) {
- // Don't need guard page for implicit checks in indexed addressing
- // mode with zero based Compressed Oops.
- Universe::set_narrow_oop_use_implicit_null_checks(true);
- }
-#endif // _WIN64
- if((uint64_t)Universe::heap()->reserved_region().end() > UnscaledOopHeapMax) {
- // Can't reserve heap below 4Gb.
+ if ((uint64_t)Universe::heap()->reserved_region().end() > UnscaledOopHeapMax) {
+ // Didn't reserve heap below 4Gb. Must shift.
Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
- } else {
- Universe::set_narrow_oop_shift(0);
}
+ if ((uint64_t)Universe::heap()->reserved_region().end() <= OopEncodingHeapMax) {
+ // Did reserve heap below 32Gb. Can use base == 0;
+ Universe::set_narrow_oop_base(0);
}
Universe::set_narrow_ptrs_base(Universe::narrow_oop_base());
if (PrintCompressedOopsMode || (PrintMiscellaneous && Verbose)) {
@@ -898,75 +784,208 @@
Universe::heap()->base(), Universe::heap()->reserved_region().byte_size()/M);
tty->print(", Compressed Oops mode: %s", narrow_oop_mode_to_string(narrow_oop_mode()));
if (Universe::narrow_oop_base() != 0) {
- tty->print(":" PTR_FORMAT, Universe::narrow_oop_base());
+ tty->print(": " PTR_FORMAT, Universe::narrow_oop_base());
}
if (Universe::narrow_oop_shift() != 0) {
tty->print(", Oop shift amount: %d", Universe::narrow_oop_shift());
}
+ if (!Universe::narrow_oop_use_implicit_null_checks()) {
+ tty->print(", no protected page in front of the heap");
+ }
+
tty->cr();
tty->cr();
}
-// Reserve the Java heap, which is now the same for all GCs.
+#define SIZE_64K ((uint64_t) 0x10000ULL)
+#define SIZE_256M ((uint64_t) 0x10000000ULL)
+#define SIZE_32G ((uint64_t) 0x800000000ULL)
+
+// Helper for heap allocation. Returns an array with addresses
+// (OS-specific) which are suited for disjoint base mode. Array is
+// NULL terminated.
+static char** get_attach_addresses_for_disjoint_mode() {
+ static uintptr_t addresses[] = {
+#ifdef _LP64
+ 2 * SIZE_32G,
+ 3 * SIZE_32G,
+ 4 * SIZE_32G,
+ 8 * SIZE_32G,
+ 10 * SIZE_32G,
+ 1 * SIZE_64K * SIZE_32G,
+ 2 * SIZE_64K * SIZE_32G,
+ 3 * SIZE_64K * SIZE_32G,
+ 4 * SIZE_64K * SIZE_32G,
+ 16 * SIZE_64K * SIZE_32G,
+ 32 * SIZE_64K * SIZE_32G,
+ 34 * SIZE_64K * SIZE_32G,
+#endif
+ 0
+ };
+
+ // Sort out addresses smaller than HeapBaseMinAddress. This assumes
+ // the array is sorted.
+ uint i = 0;
+ while (addresses[i] != 0 &&
+ (addresses[i] < OopEncodingHeapMax || addresses[i] < HeapBaseMinAddress)) {
+ i++;
+ }
+ uint start = i;
+
+ // Avoid more steps than requested.
+ i = 0;
+ while (addresses[start+i] != 0) {
+ if (i == HeapSearchSteps) {
+ addresses[start+i] = 0;
+ break;
+ }
+ i++;
+ }
+
+ return (char**) &addresses[start];
+}
+
ReservedSpace Universe::reserve_heap(size_t heap_size, size_t alignment) {
+
assert(alignment <= Arguments::conservative_max_heap_alignment(),
err_msg("actual alignment "SIZE_FORMAT" must be within maximum heap alignment "SIZE_FORMAT,
alignment, Arguments::conservative_max_heap_alignment()));
+
size_t total_reserved = align_size_up(heap_size, alignment);
assert(!UseCompressedOops || (total_reserved <= (OopEncodingHeapMax - os::vm_page_size())),
"heap size is too big for compressed oops");
bool use_large_pages = UseLargePages && is_size_aligned(alignment, os::large_page_size());
assert(!UseLargePages
|| UseParallelGC
|| use_large_pages, "Wrong alignment to use large pages");
- char* addr = Universe::preferred_heap_base(total_reserved, alignment, Universe::UnscaledNarrowOop);
-
- ReservedHeapSpace total_rs(total_reserved, alignment, use_large_pages, addr);
+ // Address where to allocate the heap. NULL: anywhere.
+ char* addr = NULL;
+ size_t disjoint_noaccess_prefix = 0;
if (UseCompressedOops) {
- if (addr != NULL && !total_rs.is_reserved()) {
- // Failed to reserve at specified address - the requested memory
- // region is taken already, for example, by 'java' launcher.
- // Try again to reserver heap higher.
- addr = Universe::preferred_heap_base(total_reserved, alignment, Universe::ZeroBasedNarrowOop);
-
- ReservedHeapSpace total_rs0(total_reserved, alignment,
- use_large_pages, addr);
-
- if (addr != NULL && !total_rs0.is_reserved()) {
- // Failed to reserve at specified address again - give up.
- addr = Universe::preferred_heap_base(total_reserved, alignment, Universe::HeapBasedNarrowOop);
- assert(addr == NULL, "");
+ // Try to get a heap by:
+ // 0) if HeapBaseMinAddress is set, try this address first.
+ // 1) get heap for unscaled (base = 0, shift = 0)
+ // 2) failing that, get heap for zerobased (base = 0, shift != 0)
+ // 3) failing that, get heap for disjointbase (base != 0, shift != 0)
+ // 4) failing that, any heap will do.
+
+ // Loop over compressed oop modes; try to obtain a fitting memory range;
+ // if success, release it again and let ReservedHeapSpace attempt to
+ // allocate in the same range.
+ for (int i = 0; i <= 4; i++) {
+ disjoint_noaccess_prefix = 0;
+ switch (i) {
+ case 0:
+ // Attempt to alloc at user-given address.
+ if (!FLAG_IS_DEFAULT(HeapBaseMinAddress)) {
+ addr = os::attempt_reserve_memory_at(total_reserved, (char *)HeapBaseMinAddress);
+ if (is_disjoint_heap_base_address((address)addr)) {
+ disjoint_noaccess_prefix = ReservedHeapSpace::noaccess_prefix_size(alignment);
+ }
+ }
+ break;
+ case 1:
+ // Attempt to alloc for unscaled.
+ addr = os::attempt_reserve_memory_in_range(total_reserved, alignment,
+ (char*) HeapBaseMinAddress,
+ (char*) UnscaledOopHeapMax,
+ HeapSearchSteps);
+ break;
+ case 2:
+ {
+ // zerobased: Attempt to allocate in the lower 32G.
+ // But leave room for the compressed class pointers.
+ char* zerobased_max = (char*)OopEncodingHeapMax;
- ReservedHeapSpace total_rs1(total_reserved, alignment,
- use_large_pages, addr);
- total_rs = total_rs1;
- } else {
- total_rs = total_rs0;
+ // 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");
+ zerobased_max = (char*) OopEncodingHeapMax - class_space;
}
+
+ addr = os::attempt_reserve_memory_in_range(total_reserved, alignment,
+ (char*) MAX2((char*)UnscaledOopHeapMax, (char*)HeapBaseMinAddress),
+ (char*) zerobased_max,
+ HeapSearchSteps);
+ }
+ break;
+ case 3:
+ // disjointbase. Here we just try a bushel of OS-dependend known
+ // disjoint-based friendly addresses.
+ {
+ char** addresses = get_attach_addresses_for_disjoint_mode();
+ addr = os::attempt_reserve_memory_at_multiple(total_reserved, addresses);
+ disjoint_noaccess_prefix = ReservedHeapSpace::noaccess_prefix_size(alignment);
+ }
+ break;
+ case 4:
+ addr = 0;
+ break;
+ default:
+ ShouldNotReachHere();
}
+
+ // If we could not find space for the current mode, try the next mode.
+ if (!addr && i < 4) {
+ continue;
}
- if (!total_rs.is_reserved()) {
- vm_exit_during_initialization(err_msg("Could not reserve enough space for " SIZE_FORMAT "KB object heap", total_reserved/K));
- return total_rs;
+ // If we did find space, release space; ReservedHeapSpace will allocate
+ // again.
+ if (addr) {
+ os::release_memory(addr, total_reserved);
+ break; // Quit the for loop.
+ }
+
+ } // for loop
+ }
+
+ // now create the space
+ ReservedHeapSpace total_rs(total_reserved, alignment,
+ use_large_pages, addr + disjoint_noaccess_prefix);
+
+ if (addr != NULL && !total_rs.is_reserved()) {
+ // Try arbitrary position.
+ ReservedHeapSpace total_rs1(total_reserved, alignment, use_large_pages, NULL);
+ disjoint_noaccess_prefix = 0;
+ total_rs = total_rs1;
}
+ if (total_rs.is_reserved()) {
+ // we are good.
+
if (UseCompressedOops) {
// Universe::initialize_heap() will reset this to NULL if unscaled
// or zero-based narrow oops are actually used.
- address base = (address)(total_rs.base() - os::vm_page_size());
+ // SAPJVM GL 2014-09-22
+ // Else heap start and base MUST differ, so that NULL can be encoded nonambigous.
+ address base = (address)(total_rs.base() - ReservedHeapSpace::noaccess_prefix_size(alignment));
Universe::set_narrow_oop_base(base);
}
+
return total_rs;
+ }
+
+ vm_exit_during_initialization(
+ err_msg("Could not reserve enough space for " SIZE_FORMAT "KB object heap",
+ total_reserved/K));
+
+ // satisfy compiler
+ ShouldNotReachHere();
+ return ReservedHeapSpace(0, 0, false, 0);
}
// It's the caller's responsibility to ensure glitch-freedom
// (if required).
@@ -980,20 +999,26 @@
switch (mode) {
case UnscaledNarrowOop:
return "32-bit";
case ZeroBasedNarrowOop:
return "Zero based";
+ case DisjointBaseNarrowOop:
+ return "Non-zero disjoint base";
case HeapBasedNarrowOop:
return "Non-zero based";
}
ShouldNotReachHere();
return "";
}
Universe::NARROW_OOP_MODE Universe::narrow_oop_mode() {
+ if (narrow_oop_base_disjoint()) {
+ return DisjointBaseNarrowOop;
+ }
+
if (narrow_oop_base() != 0) {
return HeapBasedNarrowOop;
}
if (narrow_oop_shift() != 0) {
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