Mercurial > hg > release > icedtea7-forest-2.2 > hotspot
changeset 2457:7f3faf7159fd
Merge
| author | jmasa |
|---|---|
| date | Fri, 22 Apr 2011 09:26:09 -0700 |
| parents | 732454aaf5cb (current diff) b52782ae3880 (diff) |
| children | d6cdc6c77582 |
| files | src/os/linux/vm/os_linux.cpp |
| diffstat | 19 files changed, 918 insertions(+), 298 deletions(-) [+] |
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line diff
--- a/src/os/linux/vm/globals_linux.hpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/os/linux/vm/globals_linux.hpp Fri Apr 22 09:26:09 2011 -0700 @@ -29,13 +29,19 @@ // Defines Linux specific flags. They are not available on other platforms. // #define RUNTIME_OS_FLAGS(develop, develop_pd, product, product_pd, diagnostic, notproduct) \ - product(bool, UseOprofile, false, \ - "enable support for Oprofile profiler") \ - \ - product(bool, UseLinuxPosixThreadCPUClocks, true, \ - "enable fast Linux Posix clocks where available") -// NB: The default value of UseLinuxPosixThreadCPUClocks may be -// overridden in Arguments::parse_each_vm_init_arg. + product(bool, UseOprofile, false, \ + "enable support for Oprofile profiler") \ + \ + product(bool, UseLinuxPosixThreadCPUClocks, true, \ + "enable fast Linux Posix clocks where available") \ +/* NB: The default value of UseLinuxPosixThreadCPUClocks may be \ + overridden in Arguments::parse_each_vm_init_arg. */ \ + \ + product(bool, UseHugeTLBFS, false, \ + "Use MAP_HUGETLB for large pages") \ + \ + product(bool, UseSHM, false, \ + "Use SYSV shared memory for large pages") // // Defines Linux-specific default values. The flags are available on all
--- a/src/os/linux/vm/os_linux.cpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/os/linux/vm/os_linux.cpp Fri Apr 22 09:26:09 2011 -0700 @@ -2465,16 +2465,40 @@ return res != (uintptr_t) MAP_FAILED; } +// Define MAP_HUGETLB here so we can build HotSpot on old systems. +#ifndef MAP_HUGETLB +#define MAP_HUGETLB 0x40000 +#endif + +// Define MADV_HUGEPAGE here so we can build HotSpot on old systems. +#ifndef MADV_HUGEPAGE +#define MADV_HUGEPAGE 14 +#endif + bool os::commit_memory(char* addr, size_t size, size_t alignment_hint, bool exec) { + if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) { + int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; + uintptr_t res = + (uintptr_t) ::mmap(addr, size, prot, + MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS|MAP_HUGETLB, + -1, 0); + return res != (uintptr_t) MAP_FAILED; + } + return commit_memory(addr, size, exec); } -void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) { } +void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) { + if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) { + // We don't check the return value: madvise(MADV_HUGEPAGE) may not + // be supported or the memory may already be backed by huge pages. + ::madvise(addr, bytes, MADV_HUGEPAGE); + } +} void os::free_memory(char *addr, size_t bytes) { - ::mmap(addr, bytes, PROT_READ | PROT_WRITE, - MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); + ::madvise(addr, bytes, MADV_DONTNEED); } void os::numa_make_global(char *addr, size_t bytes) { @@ -2812,6 +2836,43 @@ return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); } +bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { + bool result = false; + void *p = mmap (NULL, page_size, PROT_READ|PROT_WRITE, + MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, + -1, 0); + + if (p != (void *) -1) { + // We don't know if this really is a huge page or not. + FILE *fp = fopen("/proc/self/maps", "r"); + if (fp) { + while (!feof(fp)) { + char chars[257]; + long x = 0; + if (fgets(chars, sizeof(chars), fp)) { + if (sscanf(chars, "%lx-%*lx", &x) == 1 + && x == (long)p) { + if (strstr (chars, "hugepage")) { + result = true; + break; + } + } + } + } + fclose(fp); + } + munmap (p, page_size); + if (result) + return true; + } + + if (warn) { + warning("HugeTLBFS is not supported by the operating system."); + } + + return result; +} + /* * Set the coredump_filter bits to include largepages in core dump (bit 6) * @@ -2854,7 +2915,16 @@ static size_t _large_page_size = 0; bool os::large_page_init() { - if (!UseLargePages) return false; + if (!UseLargePages) { + UseHugeTLBFS = false; + UseSHM = false; + return false; + } + + if (FLAG_IS_DEFAULT(UseHugeTLBFS) && FLAG_IS_DEFAULT(UseSHM)) { + // Our user has not expressed a preference, so we'll try both. + UseHugeTLBFS = UseSHM = true; + } if (LargePageSizeInBytes) { _large_page_size = LargePageSizeInBytes; @@ -2899,6 +2969,9 @@ } } + // print a warning if any large page related flag is specified on command line + bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); + const size_t default_page_size = (size_t)Linux::page_size(); if (_large_page_size > default_page_size) { _page_sizes[0] = _large_page_size; @@ -2906,6 +2979,14 @@ _page_sizes[2] = 0; } + UseHugeTLBFS = UseHugeTLBFS && + Linux::hugetlbfs_sanity_check(warn_on_failure, _large_page_size); + + if (UseHugeTLBFS) + UseSHM = false; + + UseLargePages = UseHugeTLBFS || UseSHM; + set_coredump_filter(); // Large page support is available on 2.6 or newer kernel, some vendors @@ -2922,7 +3003,7 @@ char* os::reserve_memory_special(size_t bytes, char* req_addr, bool exec) { // "exec" is passed in but not used. Creating the shared image for // the code cache doesn't have an SHM_X executable permission to check. - assert(UseLargePages, "only for large pages"); + assert(UseLargePages && UseSHM, "only for SHM large pages"); key_t key = IPC_PRIVATE; char *addr; @@ -2989,16 +3070,15 @@ return _large_page_size; } -// Linux does not support anonymous mmap with large page memory. The only way -// to reserve large page memory without file backing is through SysV shared -// memory API. The entire memory region is committed and pinned upfront. -// Hopefully this will change in the future... +// HugeTLBFS allows application to commit large page memory on demand; +// with SysV SHM the entire memory region must be allocated as shared +// memory. bool os::can_commit_large_page_memory() { - return false; + return UseHugeTLBFS; } bool os::can_execute_large_page_memory() { - return false; + return UseHugeTLBFS; } // Reserve memory at an arbitrary address, only if that area is
--- a/src/os/linux/vm/os_linux.hpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/os/linux/vm/os_linux.hpp Fri Apr 22 09:26:09 2011 -0700 @@ -86,6 +86,9 @@ static void rebuild_cpu_to_node_map(); static GrowableArray<int>* cpu_to_node() { return _cpu_to_node; } + + static bool hugetlbfs_sanity_check(bool warn, size_t page_size); + public: static void init_thread_fpu_state(); static int get_fpu_control_word();
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp Fri Apr 22 09:26:09 2011 -0700 @@ -1161,6 +1161,7 @@ TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty); + TraceCollectorStats tcs(g1mm()->full_collection_counters()); TraceMemoryManagerStats tms(true /* fullGC */); double start = os::elapsedTime(); @@ -1339,6 +1340,7 @@ if (PrintHeapAtGC) { Universe::print_heap_after_gc(); } + g1mm()->update_counters(); return true; } @@ -1971,6 +1973,10 @@ init_mutator_alloc_region(); + // Do create of the monitoring and management support so that + // values in the heap have been properly initialized. + _g1mm = new G1MonitoringSupport(this, &_g1_storage); + return JNI_OK; } @@ -2113,6 +2119,28 @@ (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)); } +#ifndef PRODUCT +void G1CollectedHeap::allocate_dummy_regions() { + // Let's fill up most of the region + size_t word_size = HeapRegion::GrainWords - 1024; + // And as a result the region we'll allocate will be humongous. + guarantee(isHumongous(word_size), "sanity"); + + for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { + // Let's use the existing mechanism for the allocation + HeapWord* dummy_obj = humongous_obj_allocate(word_size); + if (dummy_obj != NULL) { + MemRegion mr(dummy_obj, word_size); + CollectedHeap::fill_with_object(mr); + } else { + // If we can't allocate once, we probably cannot allocate + // again. Let's get out of the loop. + break; + } + } +} +#endif // !PRODUCT + void G1CollectedHeap::increment_full_collections_completed(bool concurrent) { MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); @@ -3164,6 +3192,7 @@ TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty); + TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); TraceMemoryManagerStats tms(false /* fullGC */); // If the secondary_free_list is not empty, append it to the @@ -3338,6 +3367,8 @@ doConcurrentMark(); } + allocate_dummy_regions(); + #if YOUNG_LIST_VERBOSE gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); _young_list->print(); @@ -3401,6 +3432,8 @@ if (PrintHeapAtGC) { Universe::print_heap_after_gc(); } + g1mm()->update_counters(); + if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { @@ -5314,6 +5347,7 @@ if (new_alloc_region != NULL) { g1_policy()->update_region_num(true /* next_is_young */); set_region_short_lived_locked(new_alloc_region); + g1mm()->update_eden_counters(); return new_alloc_region; } }
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp Fri Apr 22 09:26:09 2011 -0700 @@ -28,7 +28,9 @@ #include "gc_implementation/g1/concurrentMark.hpp" #include "gc_implementation/g1/g1AllocRegion.hpp" #include "gc_implementation/g1/g1RemSet.hpp" +#include "gc_implementation/g1/g1MonitoringSupport.hpp" #include "gc_implementation/g1/heapRegionSets.hpp" +#include "gc_implementation/shared/hSpaceCounters.hpp" #include "gc_implementation/parNew/parGCAllocBuffer.hpp" #include "memory/barrierSet.hpp" #include "memory/memRegion.hpp" @@ -57,6 +59,7 @@ class ConcurrentMark; class ConcurrentMarkThread; class ConcurrentG1Refine; +class GenerationCounters; typedef OverflowTaskQueue<StarTask> RefToScanQueue; typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet; @@ -236,6 +239,9 @@ // current collection. HeapRegion* _gc_alloc_region_list; + // Helper for monitoring and management support. + G1MonitoringSupport* _g1mm; + // Determines PLAB size for a particular allocation purpose. static size_t desired_plab_sz(GCAllocPurpose purpose); @@ -298,6 +304,14 @@ // started is maintained in _total_full_collections in CollectedHeap. volatile unsigned int _full_collections_completed; + // This is a non-product method that is helpful for testing. It is + // called at the end of a GC and artificially expands the heap by + // allocating a number of dead regions. This way we can induce very + // frequent marking cycles and stress the cleanup / concurrent + // cleanup code more (as all the regions that will be allocated by + // this method will be found dead by the marking cycle). + void allocate_dummy_regions() PRODUCT_RETURN; + // These are macros so that, if the assert fires, we get the correct // line number, file, etc. @@ -542,6 +556,9 @@ HeapWord* expand_and_allocate(size_t word_size); public: + + G1MonitoringSupport* g1mm() { return _g1mm; } + // Expand the garbage-first heap by at least the given size (in bytes!). // Returns true if the heap was expanded by the requested amount; // false otherwise.
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/g1/g1MonitoringSupport.cpp Fri Apr 22 09:26:09 2011 -0700 @@ -0,0 +1,178 @@ +/* + * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#include "precompiled.hpp" +#include "gc_implementation/g1/g1MonitoringSupport.hpp" +#include "gc_implementation/g1/g1CollectedHeap.inline.hpp" +#include "gc_implementation/g1/g1CollectorPolicy.hpp" + +G1MonitoringSupport::G1MonitoringSupport(G1CollectedHeap* g1h, + VirtualSpace* g1_storage_addr) : + _g1h(g1h), + _incremental_collection_counters(NULL), + _full_collection_counters(NULL), + _non_young_collection_counters(NULL), + _old_space_counters(NULL), + _young_collection_counters(NULL), + _eden_counters(NULL), + _from_counters(NULL), + _to_counters(NULL), + _g1_storage_addr(g1_storage_addr) +{ + // Counters for GC collections + // + // name "collector.0". In a generational collector this would be the + // young generation collection. + _incremental_collection_counters = + new CollectorCounters("G1 incremental collections", 0); + // name "collector.1". In a generational collector this would be the + // old generation collection. + _full_collection_counters = + new CollectorCounters("G1 stop-the-world full collections", 1); + + // timer sampling for all counters supporting sampling only update the + // used value. See the take_sample() method. G1 requires both used and + // capacity updated so sampling is not currently used. It might + // be sufficient to update all counters in take_sample() even though + // take_sample() only returns "used". When sampling was used, there + // were some anomolous values emitted which may have been the consequence + // of not updating all values simultaneously (i.e., see the calculation done + // in eden_space_used(), is it possbile that the values used to + // calculate either eden_used or survivor_used are being updated by + // the collector when the sample is being done?). + const bool sampled = false; + + // "Generation" and "Space" counters. + // + // name "generation.1" This is logically the old generation in + // generational GC terms. The "1, 1" parameters are for + // the n-th generation (=1) with 1 space. + // Counters are created from minCapacity, maxCapacity, and capacity + _non_young_collection_counters = + new GenerationCounters("whole heap", 1, 1, _g1_storage_addr); + + // name "generation.1.space.0" + // Counters are created from maxCapacity, capacity, initCapacity, + // and used. + _old_space_counters = new HSpaceCounters("space", 0, + _g1h->max_capacity(), _g1h->capacity(), _non_young_collection_counters); + + // Young collection set + // name "generation.0". This is logically the young generation. + // The "0, 3" are paremeters for the n-th genertaion (=0) with 3 spaces. + // See _non_young_collection_counters for additional counters + _young_collection_counters = new GenerationCounters("young", 0, 3, NULL); + + // Replace "max_heap_byte_size() with maximum young gen size for + // g1Collectedheap + // name "generation.0.space.0" + // See _old_space_counters for additional counters + _eden_counters = new HSpaceCounters("eden", 0, + _g1h->max_capacity(), eden_space_committed(), + _young_collection_counters); + + // name "generation.0.space.1" + // See _old_space_counters for additional counters + // Set the arguments to indicate that this survivor space is not used. + _from_counters = new HSpaceCounters("s0", 1, (long) 0, (long) 0, + _young_collection_counters); + + // name "generation.0.space.2" + // See _old_space_counters for additional counters + _to_counters = new HSpaceCounters("s1", 2, + _g1h->max_capacity(), + survivor_space_committed(), + _young_collection_counters); +} + +size_t G1MonitoringSupport::overall_committed() { + return g1h()->capacity(); +} + +size_t G1MonitoringSupport::overall_used() { + return g1h()->used_unlocked(); +} + +size_t G1MonitoringSupport::eden_space_committed() { + return MAX2(eden_space_used(), (size_t) HeapRegion::GrainBytes); +} + +size_t G1MonitoringSupport::eden_space_used() { + size_t young_list_length = g1h()->young_list()->length(); + size_t eden_used = young_list_length * HeapRegion::GrainBytes; + size_t survivor_used = survivor_space_used(); + eden_used = subtract_up_to_zero(eden_used, survivor_used); + return eden_used; +} + +size_t G1MonitoringSupport::survivor_space_committed() { + return MAX2(survivor_space_used(), + (size_t) HeapRegion::GrainBytes); +} + +size_t G1MonitoringSupport::survivor_space_used() { + size_t survivor_num = g1h()->g1_policy()->recorded_survivor_regions(); + size_t survivor_used = survivor_num * HeapRegion::GrainBytes; + return survivor_used; +} + +size_t G1MonitoringSupport::old_space_committed() { + size_t committed = overall_committed(); + size_t eden_committed = eden_space_committed(); + size_t survivor_committed = survivor_space_committed(); + committed = subtract_up_to_zero(committed, eden_committed); + committed = subtract_up_to_zero(committed, survivor_committed); + committed = MAX2(committed, (size_t) HeapRegion::GrainBytes); + return committed; +} + +// See the comment near the top of g1MonitoringSupport.hpp for +// an explanation of these calculations for "used" and "capacity". +size_t G1MonitoringSupport::old_space_used() { + size_t used = overall_used(); + size_t eden_used = eden_space_used(); + size_t survivor_used = survivor_space_used(); + used = subtract_up_to_zero(used, eden_used); + used = subtract_up_to_zero(used, survivor_used); + return used; +} + +void G1MonitoringSupport::update_counters() { + if (UsePerfData) { + eden_counters()->update_capacity(eden_space_committed()); + eden_counters()->update_used(eden_space_used()); + to_counters()->update_capacity(survivor_space_committed()); + to_counters()->update_used(survivor_space_used()); + old_space_counters()->update_capacity(old_space_committed()); + old_space_counters()->update_used(old_space_used()); + non_young_collection_counters()->update_all(); + } +} + +void G1MonitoringSupport::update_eden_counters() { + if (UsePerfData) { + eden_counters()->update_capacity(eden_space_committed()); + eden_counters()->update_used(eden_space_used()); + } +}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/g1/g1MonitoringSupport.hpp Fri Apr 22 09:26:09 2011 -0700 @@ -0,0 +1,203 @@ +/* + * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP +#define SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP + +#include "gc_implementation/shared/hSpaceCounters.hpp" + +class G1CollectedHeap; +class G1SpaceMonitoringSupport; + +// Class for monitoring logical spaces in G1. +// G1 defines a set of regions as a young +// collection (analogous to a young generation). +// The young collection is a logical generation +// with no fixed chunk (see space.hpp) reflecting +// the address space for the generation. In addition +// to the young collection there is its complement +// the non-young collection that is simply the regions +// not in the young collection. The non-young collection +// is treated here as a logical old generation only +// because the monitoring tools expect a generational +// heap. The monitoring tools expect that a Space +// (see space.hpp) exists that describe the +// address space of young collection and non-young +// collection and such a view is provided here. +// +// This class provides interfaces to access +// the value of variables for the young collection +// that include the "capacity" and "used" of the +// young collection along with constant values +// for the minimum and maximum capacities for +// the logical spaces. Similarly for the non-young +// collection. +// +// Also provided are counters for G1 concurrent collections +// and stop-the-world full heap collecitons. +// +// Below is a description of how "used" and "capactiy" +// (or committed) is calculated for the logical spaces. +// +// 1) The used space calculation for a pool is not necessarily +// independent of the others. We can easily get from G1 the overall +// used space in the entire heap, the number of regions in the young +// generation (includes both eden and survivors), and the number of +// survivor regions. So, from that we calculate: +// +// survivor_used = survivor_num * region_size +// eden_used = young_region_num * region_size - survivor_used +// old_gen_used = overall_used - eden_used - survivor_used +// +// Note that survivor_used and eden_used are upper bounds. To get the +// actual value we would have to iterate over the regions and add up +// ->used(). But that'd be expensive. So, we'll accept some lack of +// accuracy for those two. But, we have to be careful when calculating +// old_gen_used, in case we subtract from overall_used more then the +// actual number and our result goes negative. +// +// 2) Calculating the used space is straightforward, as described +// above. However, how do we calculate the committed space, given that +// we allocate space for the eden, survivor, and old gen out of the +// same pool of regions? One way to do this is to use the used value +// as also the committed value for the eden and survivor spaces and +// then calculate the old gen committed space as follows: +// +// old_gen_committed = overall_committed - eden_committed - survivor_committed +// +// Maybe a better way to do that would be to calculate used for eden +// and survivor as a sum of ->used() over their regions and then +// calculate committed as region_num * region_size (i.e., what we use +// to calculate the used space now). This is something to consider +// in the future. +// +// 3) Another decision that is again not straightforward is what is +// the max size that each memory pool can grow to. One way to do this +// would be to use the committed size for the max for the eden and +// survivors and calculate the old gen max as follows (basically, it's +// a similar pattern to what we use for the committed space, as +// described above): +// +// old_gen_max = overall_max - eden_max - survivor_max +// +// Unfortunately, the above makes the max of each pool fluctuate over +// time and, even though this is allowed according to the spec, it +// broke several assumptions in the M&M framework (there were cases +// where used would reach a value greater than max). So, for max we +// use -1, which means "undefined" according to the spec. +// +// 4) Now, there is a very subtle issue with all the above. The +// framework will call get_memory_usage() on the three pools +// asynchronously. As a result, each call might get a different value +// for, say, survivor_num which will yield inconsistent values for +// eden_used, survivor_used, and old_gen_used (as survivor_num is used +// in the calculation of all three). This would normally be +// ok. However, it's possible that this might cause the sum of +// eden_used, survivor_used, and old_gen_used to go over the max heap +// size and this seems to sometimes cause JConsole (and maybe other +// clients) to get confused. There's not a really an easy / clean +// solution to this problem, due to the asynchrounous nature of the +// framework. + +class G1MonitoringSupport : public CHeapObj { + G1CollectedHeap* _g1h; + VirtualSpace* _g1_storage_addr; + + // jstat performance counters + // incremental collections both fully and partially young + CollectorCounters* _incremental_collection_counters; + // full stop-the-world collections + CollectorCounters* _full_collection_counters; + // young collection set counters. The _eden_counters, + // _from_counters, and _to_counters are associated with + // this "generational" counter. + GenerationCounters* _young_collection_counters; + // non-young collection set counters. The _old_space_counters + // below are associated with this "generational" counter. + GenerationCounters* _non_young_collection_counters; + // Counters for the capacity and used for + // the whole heap + HSpaceCounters* _old_space_counters; + // the young collection + HSpaceCounters* _eden_counters; + // the survivor collection (only one, _to_counters, is actively used) + HSpaceCounters* _from_counters; + HSpaceCounters* _to_counters; + + // It returns x - y if x > y, 0 otherwise. + // As described in the comment above, some of the inputs to the + // calculations we have to do are obtained concurrently and hence + // may be inconsistent with each other. So, this provides a + // defensive way of performing the subtraction and avoids the value + // going negative (which would mean a very large result, given that + // the parameter are size_t). + static size_t subtract_up_to_zero(size_t x, size_t y) { + if (x > y) { + return x - y; + } else { + return 0; + } + } + + public: + G1MonitoringSupport(G1CollectedHeap* g1h, VirtualSpace* g1_storage_addr); + + G1CollectedHeap* g1h() { return _g1h; } + VirtualSpace* g1_storage_addr() { return _g1_storage_addr; } + + // Performance Counter accessors + void update_counters(); + void update_eden_counters(); + + CollectorCounters* incremental_collection_counters() { + return _incremental_collection_counters; + } + CollectorCounters* full_collection_counters() { + return _full_collection_counters; + } + GenerationCounters* non_young_collection_counters() { + return _non_young_collection_counters; + } + HSpaceCounters* old_space_counters() { return _old_space_counters; } + HSpaceCounters* eden_counters() { return _eden_counters; } + HSpaceCounters* from_counters() { return _from_counters; } + HSpaceCounters* to_counters() { return _to_counters; } + + // Monitoring support used by + // MemoryService + // jstat counters + size_t overall_committed(); + size_t overall_used(); + + size_t eden_space_committed(); + size_t eden_space_used(); + + size_t survivor_space_committed(); + size_t survivor_space_used(); + + size_t old_space_committed(); + size_t old_space_used(); +}; + +#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP
--- a/src/share/vm/gc_implementation/g1/g1_globals.hpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/gc_implementation/g1/g1_globals.hpp Fri Apr 22 09:26:09 2011 -0700 @@ -300,6 +300,11 @@ develop(uintx, G1StressConcRegionFreeingDelayMillis, 0, \ "Artificial delay during concurrent region freeing") \ \ + develop(uintx, G1DummyRegionsPerGC, 0, \ + "The number of dummy regions G1 will allocate at the end of " \ + "each evacuation pause in order to artificially fill up the " \ + "heap and stress the marking implementation.") \ + \ develop(bool, ReduceInitialCardMarksForG1, false, \ "When ReduceInitialCardMarks is true, this flag setting " \ " controls whether G1 allows the RICM optimization") \
--- a/src/share/vm/gc_implementation/parNew/parCardTableModRefBS.cpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/gc_implementation/parNew/parCardTableModRefBS.cpp Fri Apr 22 09:26:09 2011 -0700 @@ -33,44 +33,43 @@ #include "runtime/mutexLocker.hpp" #include "runtime/virtualspace.hpp" -void CardTableModRefBS::par_non_clean_card_iterate_work(Space* sp, MemRegion mr, - DirtyCardToOopClosure* dcto_cl, - MemRegionClosure* cl, - int n_threads) { - if (n_threads > 0) { - assert((n_threads == 1 && ParallelGCThreads == 0) || - n_threads <= (int)ParallelGCThreads, - "# worker threads != # requested!"); - // Make sure the LNC array is valid for the space. - jbyte** lowest_non_clean; - uintptr_t lowest_non_clean_base_chunk_index; - size_t lowest_non_clean_chunk_size; - get_LNC_array_for_space(sp, lowest_non_clean, - lowest_non_clean_base_chunk_index, - lowest_non_clean_chunk_size); +void CardTableModRefBS::non_clean_card_iterate_parallel_work(Space* sp, MemRegion mr, + DirtyCardToOopClosure* dcto_cl, + ClearNoncleanCardWrapper* cl, + int n_threads) { + assert(n_threads > 0, "Error: expected n_threads > 0"); + assert((n_threads == 1 && ParallelGCThreads == 0) || + n_threads <= (int)ParallelGCThreads, + "# worker threads != # requested!"); + // Make sure the LNC array is valid for the space. + jbyte** lowest_non_clean; + uintptr_t lowest_non_clean_base_chunk_index; + size_t lowest_non_clean_chunk_size; + get_LNC_array_for_space(sp, lowest_non_clean, + lowest_non_clean_base_chunk_index, + lowest_non_clean_chunk_size); - int n_strides = n_threads * StridesPerThread; - SequentialSubTasksDone* pst = sp->par_seq_tasks(); - pst->set_n_threads(n_threads); - pst->set_n_tasks(n_strides); + int n_strides = n_threads * StridesPerThread; + SequentialSubTasksDone* pst = sp->par_seq_tasks(); + pst->set_n_threads(n_threads); + pst->set_n_tasks(n_strides); - int stride = 0; - while (!pst->is_task_claimed(/* reference */ stride)) { - process_stride(sp, mr, stride, n_strides, dcto_cl, cl, - lowest_non_clean, - lowest_non_clean_base_chunk_index, - lowest_non_clean_chunk_size); - } - if (pst->all_tasks_completed()) { - // Clear lowest_non_clean array for next time. - intptr_t first_chunk_index = addr_to_chunk_index(mr.start()); - uintptr_t last_chunk_index = addr_to_chunk_index(mr.last()); - for (uintptr_t ch = first_chunk_index; ch <= last_chunk_index; ch++) { - intptr_t ind = ch - lowest_non_clean_base_chunk_index; - assert(0 <= ind && ind < (intptr_t)lowest_non_clean_chunk_size, - "Bounds error"); - lowest_non_clean[ind] = NULL; - } + int stride = 0; + while (!pst->is_task_claimed(/* reference */ stride)) { + process_stride(sp, mr, stride, n_strides, dcto_cl, cl, + lowest_non_clean, + lowest_non_clean_base_chunk_index, + lowest_non_clean_chunk_size); + } + if (pst->all_tasks_completed()) { + // Clear lowest_non_clean array for next time. + intptr_t first_chunk_index = addr_to_chunk_index(mr.start()); + uintptr_t last_chunk_index = addr_to_chunk_index(mr.last()); + for (uintptr_t ch = first_chunk_index; ch <= last_chunk_index; ch++) { + intptr_t ind = ch - lowest_non_clean_base_chunk_index; + assert(0 <= ind && ind < (intptr_t)lowest_non_clean_chunk_size, + "Bounds error"); + lowest_non_clean[ind] = NULL; } } } @@ -81,7 +80,7 @@ MemRegion used, jint stride, int n_strides, DirtyCardToOopClosure* dcto_cl, - MemRegionClosure* cl, + ClearNoncleanCardWrapper* cl, jbyte** lowest_non_clean, uintptr_t lowest_non_clean_base_chunk_index, size_t lowest_non_clean_chunk_size) { @@ -127,7 +126,11 @@ lowest_non_clean_base_chunk_index, lowest_non_clean_chunk_size); - non_clean_card_iterate_work(chunk_mr, cl); + // We do not call the non_clean_card_iterate_serial() version because + // we want to clear the cards, and the ClearNoncleanCardWrapper closure + // itself does the work of finding contiguous dirty ranges of cards to + // process (and clear). + cl->do_MemRegion(chunk_mr); // Find the next chunk of the stride. chunk_card_start += CardsPerStrideChunk * n_strides;
--- a/src/share/vm/gc_implementation/shared/generationCounters.cpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/gc_implementation/shared/generationCounters.cpp Fri Apr 22 09:26:09 2011 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -51,15 +51,18 @@ cname = PerfDataManager::counter_name(_name_space, "minCapacity"); PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_Bytes, + _virtual_space == NULL ? 0 : _virtual_space->committed_size(), CHECK); cname = PerfDataManager::counter_name(_name_space, "maxCapacity"); PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_Bytes, + _virtual_space == NULL ? 0 : _virtual_space->reserved_size(), CHECK); cname = PerfDataManager::counter_name(_name_space, "capacity"); _current_size = PerfDataManager::create_variable(SUN_GC, cname, - PerfData::U_Bytes, + PerfData::U_Bytes, + _virtual_space == NULL ? 0 : _virtual_space->committed_size(), CHECK); } }
--- a/src/share/vm/gc_implementation/shared/generationCounters.hpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/gc_implementation/shared/generationCounters.hpp Fri Apr 22 09:26:09 2011 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -61,10 +61,11 @@ } virtual void update_all() { - _current_size->set_value(_virtual_space->committed_size()); + _current_size->set_value(_virtual_space == NULL ? 0 : + _virtual_space->committed_size()); } const char* name_space() const { return _name_space; } + }; - #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_GENERATIONCOUNTERS_HPP
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/shared/hSpaceCounters.cpp Fri Apr 22 09:26:09 2011 -0700 @@ -0,0 +1,66 @@ +/* + * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#include "precompiled.hpp" +#include "gc_implementation/shared/hSpaceCounters.hpp" +#include "memory/generation.hpp" +#include "memory/resourceArea.hpp" + +HSpaceCounters::HSpaceCounters(const char* name, + int ordinal, + size_t max_size, + size_t initial_capacity, + GenerationCounters* gc) { + + if (UsePerfData) { + EXCEPTION_MARK; + ResourceMark rm; + + const char* cns = + PerfDataManager::name_space(gc->name_space(), "space", ordinal); + + _name_space = NEW_C_HEAP_ARRAY(char, strlen(cns)+1); + strcpy(_name_space, cns); + + const char* cname = PerfDataManager::counter_name(_name_space, "name"); + PerfDataManager::create_string_constant(SUN_GC, cname, name, CHECK); + + cname = PerfDataManager::counter_name(_name_space, "maxCapacity"); + PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_Bytes, + (jlong)max_size, CHECK); + + cname = PerfDataManager::counter_name(_name_space, "capacity"); + _capacity = PerfDataManager::create_variable(SUN_GC, cname, + PerfData::U_Bytes, + initial_capacity, CHECK); + + cname = PerfDataManager::counter_name(_name_space, "used"); + _used = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, + (jlong) 0, CHECK); + + cname = PerfDataManager::counter_name(_name_space, "initCapacity"); + PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_Bytes, + initial_capacity, CHECK); + } +}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/shared/hSpaceCounters.hpp Fri Apr 22 09:26:09 2011 -0700 @@ -0,0 +1,87 @@ +/* + * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_HSPACECOUNTERS_HPP +#define SHARE_VM_GC_IMPLEMENTATION_SHARED_HSPACECOUNTERS_HPP + +#ifndef SERIALGC +#include "gc_implementation/shared/generationCounters.hpp" +#include "memory/generation.hpp" +#include "runtime/perfData.hpp" +#endif + +// A HSpaceCounter is a holder class for performance counters +// that track a collections (logical spaces) in a heap; + +class HeapSpaceUsedHelper; +class G1SpaceMonitoringSupport; + +class HSpaceCounters: public CHeapObj { + friend class VMStructs; + + private: + PerfVariable* _capacity; + PerfVariable* _used; + + // Constant PerfData types don't need to retain a reference. + // However, it's a good idea to document them here. + + char* _name_space; + + public: + + HSpaceCounters(const char* name, int ordinal, size_t max_size, + size_t initial_capacity, GenerationCounters* gc); + + ~HSpaceCounters() { + if (_name_space != NULL) FREE_C_HEAP_ARRAY(char, _name_space); + } + + inline void update_capacity(size_t v) { + _capacity->set_value(v); + } + + inline void update_used(size_t v) { + _used->set_value(v); + } + + debug_only( + // for security reasons, we do not allow arbitrary reads from + // the counters as they may live in shared memory. + jlong used() { + return _used->get_value(); + } + jlong capacity() { + return _used->get_value(); + } + ) + + inline void update_all(size_t capacity, size_t used) { + update_capacity(capacity); + update_used(used); + } + + const char* name_space() const { return _name_space; } +}; +#endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_HSPACECOUNTERS_HPP
--- a/src/share/vm/memory/cardTableModRefBS.cpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/memory/cardTableModRefBS.cpp Fri Apr 22 09:26:09 2011 -0700 @@ -456,31 +456,35 @@ } -void CardTableModRefBS::non_clean_card_iterate(Space* sp, - MemRegion mr, - DirtyCardToOopClosure* dcto_cl, - MemRegionClosure* cl) { +void CardTableModRefBS::non_clean_card_iterate_possibly_parallel(Space* sp, + MemRegion mr, + DirtyCardToOopClosure* dcto_cl, + ClearNoncleanCardWrapper* cl) { if (!mr.is_empty()) { int n_threads = SharedHeap::heap()->n_par_threads(); if (n_threads > 0) { #ifndef SERIALGC - par_non_clean_card_iterate_work(sp, mr, dcto_cl, cl, n_threads); + non_clean_card_iterate_parallel_work(sp, mr, dcto_cl, cl, n_threads); #else // SERIALGC fatal("Parallel gc not supported here."); #endif // SERIALGC } else { - non_clean_card_iterate_work(mr, cl); + // We do not call the non_clean_card_iterate_serial() version below because + // we want to clear the cards (which non_clean_card_iterate_serial() does not + // do for us), and the ClearNoncleanCardWrapper closure itself does the work + // of finding contiguous dirty ranges of cards to process (and clear). + cl->do_MemRegion(mr); } } } -// NOTE: For this to work correctly, it is important that -// we look for non-clean cards below (so as to catch those -// marked precleaned), rather than look explicitly for dirty -// cards (and miss those marked precleaned). In that sense, -// the name precleaned is currently somewhat of a misnomer. -void CardTableModRefBS::non_clean_card_iterate_work(MemRegion mr, - MemRegionClosure* cl) { +// The iterator itself is not MT-aware, but +// MT-aware callers and closures can use this to +// accomplish dirty card iteration in parallel. The +// iterator itself does not clear the dirty cards, or +// change their values in any manner. +void CardTableModRefBS::non_clean_card_iterate_serial(MemRegion mr, + MemRegionClosure* cl) { for (int i = 0; i < _cur_covered_regions; i++) { MemRegion mri = mr.intersection(_covered[i]); if (mri.word_size() > 0) { @@ -661,7 +665,7 @@ void CardTableModRefBS::verify_clean_region(MemRegion mr) { GuaranteeNotModClosure blk(this); - non_clean_card_iterate_work(mr, &blk); + non_clean_card_iterate_serial(mr, &blk); } // To verify a MemRegion is entirely dirty this closure is passed to
--- a/src/share/vm/memory/cardTableModRefBS.hpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/memory/cardTableModRefBS.hpp Fri Apr 22 09:26:09 2011 -0700 @@ -44,6 +44,7 @@ class Generation; class OopsInGenClosure; class DirtyCardToOopClosure; +class ClearNoncleanCardWrapper; class CardTableModRefBS: public ModRefBarrierSet { // Some classes get to look at some private stuff. @@ -165,22 +166,28 @@ // Iterate over the portion of the card-table which covers the given // region mr in the given space and apply cl to any dirty sub-regions - // of mr. cl and dcto_cl must either be the same closure or cl must - // wrap dcto_cl. Both are required - neither may be NULL. Also, dcto_cl - // may be modified. Note that this function will operate in a parallel - // mode if worker threads are available. - void non_clean_card_iterate(Space* sp, MemRegion mr, - DirtyCardToOopClosure* dcto_cl, - MemRegionClosure* cl); + // of mr. Dirty cards are _not_ cleared by the iterator method itself, + // but closures may arrange to do so on their own should they so wish. + void non_clean_card_iterate_serial(MemRegion mr, MemRegionClosure* cl); - // Utility function used to implement the other versions below. - void non_clean_card_iterate_work(MemRegion mr, MemRegionClosure* cl); + // A variant of the above that will operate in a parallel mode if + // worker threads are available, and clear the dirty cards as it + // processes them. + // ClearNoncleanCardWrapper cl must wrap the DirtyCardToOopClosure dcto_cl, + // which may itself be modified by the method. + void non_clean_card_iterate_possibly_parallel(Space* sp, MemRegion mr, + DirtyCardToOopClosure* dcto_cl, + ClearNoncleanCardWrapper* cl); - void par_non_clean_card_iterate_work(Space* sp, MemRegion mr, - DirtyCardToOopClosure* dcto_cl, - MemRegionClosure* cl, - int n_threads); + private: + // Work method used to implement non_clean_card_iterate_possibly_parallel() + // above in the parallel case. + void non_clean_card_iterate_parallel_work(Space* sp, MemRegion mr, + DirtyCardToOopClosure* dcto_cl, + ClearNoncleanCardWrapper* cl, + int n_threads); + protected: // Dirty the bytes corresponding to "mr" (not all of which must be // covered.) void dirty_MemRegion(MemRegion mr); @@ -237,7 +244,7 @@ MemRegion used, jint stride, int n_strides, DirtyCardToOopClosure* dcto_cl, - MemRegionClosure* cl, + ClearNoncleanCardWrapper* cl, jbyte** lowest_non_clean, uintptr_t lowest_non_clean_base_chunk_index, size_t lowest_non_clean_chunk_size); @@ -409,14 +416,14 @@ // marking, where a dirty card may cause scanning, and summarization // marking, of objects that extend onto subsequent cards.) void mod_card_iterate(MemRegionClosure* cl) { - non_clean_card_iterate_work(_whole_heap, cl); + non_clean_card_iterate_serial(_whole_heap, cl); } // Like the "mod_cards_iterate" above, except only invokes the closure // for cards within the MemRegion "mr" (which is required to be // card-aligned and sized.) void mod_card_iterate(MemRegion mr, MemRegionClosure* cl) { - non_clean_card_iterate_work(mr, cl); + non_clean_card_iterate_serial(mr, cl); } static uintx ct_max_alignment_constraint(); @@ -493,4 +500,5 @@ void set_CTRS(CardTableRS* rs) { _rs = rs; } }; + #endif // SHARE_VM_MEMORY_CARDTABLEMODREFBS_HPP
--- a/src/share/vm/memory/cardTableRS.cpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/memory/cardTableRS.cpp Fri Apr 22 09:26:09 2011 -0700 @@ -105,107 +105,111 @@ g->younger_refs_iterate(blk); } -class ClearNoncleanCardWrapper: public MemRegionClosure { - MemRegionClosure* _dirty_card_closure; - CardTableRS* _ct; - bool _is_par; -private: - // Clears the given card, return true if the corresponding card should be - // processed. - bool clear_card(jbyte* entry) { - if (_is_par) { - while (true) { - // In the parallel case, we may have to do this several times. - jbyte entry_val = *entry; - assert(entry_val != CardTableRS::clean_card_val(), - "We shouldn't be looking at clean cards, and this should " - "be the only place they get cleaned."); - if (CardTableRS::card_is_dirty_wrt_gen_iter(entry_val) - || _ct->is_prev_youngergen_card_val(entry_val)) { - jbyte res = - Atomic::cmpxchg(CardTableRS::clean_card_val(), entry, entry_val); - if (res == entry_val) { - break; - } else { - assert(res == CardTableRS::cur_youngergen_and_prev_nonclean_card, - "The CAS above should only fail if another thread did " - "a GC write barrier."); - } - } else if (entry_val == - CardTableRS::cur_youngergen_and_prev_nonclean_card) { - // Parallelism shouldn't matter in this case. Only the thread - // assigned to scan the card should change this value. - *entry = _ct->cur_youngergen_card_val(); - break; - } else { - assert(entry_val == _ct->cur_youngergen_card_val(), - "Should be the only possibility."); - // In this case, the card was clean before, and become - // cur_youngergen only because of processing of a promoted object. - // We don't have to look at the card. - return false; - } +inline bool ClearNoncleanCardWrapper::clear_card(jbyte* entry) { + if (_is_par) { + return clear_card_parallel(entry); + } else { + return clear_card_serial(entry); + } +} + +inline bool ClearNoncleanCardWrapper::clear_card_parallel(jbyte* entry) { + while (true) { + // In the parallel case, we may have to do this several times. + jbyte entry_val = *entry; + assert(entry_val != CardTableRS::clean_card_val(), + "We shouldn't be looking at clean cards, and this should " + "be the only place they get cleaned."); + if (CardTableRS::card_is_dirty_wrt_gen_iter(entry_val) + || _ct->is_prev_youngergen_card_val(entry_val)) { + jbyte res = + Atomic::cmpxchg(CardTableRS::clean_card_val(), entry, entry_val); + if (res == entry_val) { + break; + } else { + assert(res == CardTableRS::cur_youngergen_and_prev_nonclean_card, + "The CAS above should only fail if another thread did " + "a GC write barrier."); } - return true; + } else if (entry_val == + CardTableRS::cur_youngergen_and_prev_nonclean_card) { + // Parallelism shouldn't matter in this case. Only the thread + // assigned to scan the card should change this value. + *entry = _ct->cur_youngergen_card_val(); + break; } else { - jbyte entry_val = *entry; - assert(entry_val != CardTableRS::clean_card_val(), - "We shouldn't be looking at clean cards, and this should " - "be the only place they get cleaned."); - assert(entry_val != CardTableRS::cur_youngergen_and_prev_nonclean_card, - "This should be possible in the sequential case."); - *entry = CardTableRS::clean_card_val(); - return true; + assert(entry_val == _ct->cur_youngergen_card_val(), + "Should be the only possibility."); + // In this case, the card was clean before, and become + // cur_youngergen only because of processing of a promoted object. + // We don't have to look at the card. + return false; } } + return true; +} -public: - ClearNoncleanCardWrapper(MemRegionClosure* dirty_card_closure, - CardTableRS* ct) : + +inline bool ClearNoncleanCardWrapper::clear_card_serial(jbyte* entry) { + jbyte entry_val = *entry; + assert(entry_val != CardTableRS::clean_card_val(), + "We shouldn't be looking at clean cards, and this should " + "be the only place they get cleaned."); + assert(entry_val != CardTableRS::cur_youngergen_and_prev_nonclean_card, + "This should be possible in the sequential case."); + *entry = CardTableRS::clean_card_val(); + return true; +} + +ClearNoncleanCardWrapper::ClearNoncleanCardWrapper( + MemRegionClosure* dirty_card_closure, CardTableRS* ct) : _dirty_card_closure(dirty_card_closure), _ct(ct) { _is_par = (SharedHeap::heap()->n_par_threads() > 0); +} + +void ClearNoncleanCardWrapper::do_MemRegion(MemRegion mr) { + assert(mr.word_size() > 0, "Error"); + assert(_ct->is_aligned(mr.start()), "mr.start() should be card aligned"); + // mr.end() may not necessarily be card aligned. + jbyte* cur_entry = _ct->byte_for(mr.last()); + const jbyte* limit = _ct->byte_for(mr.start()); + HeapWord* end_of_non_clean = mr.end(); + HeapWord* start_of_non_clean = end_of_non_clean; + while (cur_entry >= limit) { + HeapWord* cur_hw = _ct->addr_for(cur_entry); + if ((*cur_entry != CardTableRS::clean_card_val()) && clear_card(cur_entry)) { + // Continue the dirty range by opening the + // dirty window one card to the left. + start_of_non_clean = cur_hw; + } else { + // We hit a "clean" card; process any non-empty + // "dirty" range accumulated so far. + if (start_of_non_clean < end_of_non_clean) { + const MemRegion mrd(start_of_non_clean, end_of_non_clean); + _dirty_card_closure->do_MemRegion(mrd); + } + // Reset the dirty window, while continuing to look + // for the next dirty card that will start a + // new dirty window. + end_of_non_clean = cur_hw; + start_of_non_clean = cur_hw; + } + // Note that "cur_entry" leads "start_of_non_clean" in + // its leftward excursion after this point + // in the loop and, when we hit the left end of "mr", + // will point off of the left end of the card-table + // for "mr". + cur_entry--; } - void do_MemRegion(MemRegion mr) { - // We start at the high end of "mr", walking backwards - // while accumulating a contiguous dirty range of cards in - // [start_of_non_clean, end_of_non_clean) which we then - // process en masse. - HeapWord* end_of_non_clean = mr.end(); - HeapWord* start_of_non_clean = end_of_non_clean; - jbyte* entry = _ct->byte_for(mr.last()); - const jbyte* first_entry = _ct->byte_for(mr.start()); - while (entry >= first_entry) { - HeapWord* cur = _ct->addr_for(entry); - if (!clear_card(entry)) { - // We hit a clean card; process any non-empty - // dirty range accumulated so far. - if (start_of_non_clean < end_of_non_clean) { - MemRegion mr2(start_of_non_clean, end_of_non_clean); - _dirty_card_closure->do_MemRegion(mr2); - } - // Reset the dirty window while continuing to - // look for the next dirty window to process. - end_of_non_clean = cur; - start_of_non_clean = end_of_non_clean; - } - // Open the left end of the window one card to the left. - start_of_non_clean = cur; - // Note that "entry" leads "start_of_non_clean" in - // its leftward excursion after this point - // in the loop and, when we hit the left end of "mr", - // will point off of the left end of the card-table - // for "mr". - entry--; - } - // If the first card of "mr" was dirty, we will have - // been left with a dirty window, co-initial with "mr", - // which we now process. - if (start_of_non_clean < end_of_non_clean) { - MemRegion mr2(start_of_non_clean, end_of_non_clean); - _dirty_card_closure->do_MemRegion(mr2); - } + // If the first card of "mr" was dirty, we will have + // been left with a dirty window, co-initial with "mr", + // which we now process. + if (start_of_non_clean < end_of_non_clean) { + const MemRegion mrd(start_of_non_clean, end_of_non_clean); + _dirty_card_closure->do_MemRegion(mrd); } -}; +} + // clean (by dirty->clean before) ==> cur_younger_gen // dirty ==> cur_youngergen_and_prev_nonclean_card // precleaned ==> cur_youngergen_and_prev_nonclean_card @@ -246,8 +250,8 @@ cl->gen_boundary()); ClearNoncleanCardWrapper clear_cl(dcto_cl, this); - _ct_bs->non_clean_card_iterate(sp, sp->used_region_at_save_marks(), - dcto_cl, &clear_cl); + _ct_bs->non_clean_card_iterate_possibly_parallel(sp, sp->used_region_at_save_marks(), + dcto_cl, &clear_cl); } void CardTableRS::clear_into_younger(Generation* gen, bool clear_perm) {
--- a/src/share/vm/memory/cardTableRS.hpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/memory/cardTableRS.hpp Fri Apr 22 09:26:09 2011 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -166,4 +166,21 @@ }; +class ClearNoncleanCardWrapper: public MemRegionClosure { + MemRegionClosure* _dirty_card_closure; + CardTableRS* _ct; + bool _is_par; +private: + // Clears the given card, return true if the corresponding card should be + // processed. + inline bool clear_card(jbyte* entry); + // Work methods called by the clear_card() + inline bool clear_card_serial(jbyte* entry); + inline bool clear_card_parallel(jbyte* entry); + +public: + ClearNoncleanCardWrapper(MemRegionClosure* dirty_card_closure, CardTableRS* ct); + void do_MemRegion(MemRegion mr); +}; + #endif // SHARE_VM_MEMORY_CARDTABLERS_HPP
--- a/src/share/vm/services/g1MemoryPool.cpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/services/g1MemoryPool.cpp Fri Apr 22 09:26:09 2011 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -34,10 +34,10 @@ size_t init_size, bool support_usage_threshold) : _g1h(g1h), CollectedMemoryPool(name, - MemoryPool::Heap, - init_size, - undefined_max(), - support_usage_threshold) { + MemoryPool::Heap, + init_size, + undefined_max(), + support_usage_threshold) { assert(UseG1GC, "sanity"); } @@ -48,44 +48,27 @@ // See the comment at the top of g1MemoryPool.hpp size_t G1MemoryPoolSuper::eden_space_used(G1CollectedHeap* g1h) { - size_t young_list_length = g1h->young_list()->length(); - size_t eden_used = young_list_length * HeapRegion::GrainBytes; - size_t survivor_used = survivor_space_used(g1h); - eden_used = subtract_up_to_zero(eden_used, survivor_used); - return eden_used; + return g1h->g1mm()->eden_space_used(); } // See the comment at the top of g1MemoryPool.hpp size_t G1MemoryPoolSuper::survivor_space_committed(G1CollectedHeap* g1h) { - return MAX2(survivor_space_used(g1h), (size_t) HeapRegion::GrainBytes); + return g1h->g1mm()->survivor_space_committed(); } // See the comment at the top of g1MemoryPool.hpp size_t G1MemoryPoolSuper::survivor_space_used(G1CollectedHeap* g1h) { - size_t survivor_num = g1h->g1_policy()->recorded_survivor_regions(); - size_t survivor_used = survivor_num * HeapRegion::GrainBytes; - return survivor_used; + return g1h->g1mm()->survivor_space_used(); } // See the comment at the top of g1MemoryPool.hpp size_t G1MemoryPoolSuper::old_space_committed(G1CollectedHeap* g1h) { - size_t committed = overall_committed(g1h); - size_t eden_committed = eden_space_committed(g1h); - size_t survivor_committed = survivor_space_committed(g1h); - committed = subtract_up_to_zero(committed, eden_committed); - committed = subtract_up_to_zero(committed, survivor_committed); - committed = MAX2(committed, (size_t) HeapRegion::GrainBytes); - return committed; + return g1h->g1mm()->old_space_committed(); } // See the comment at the top of g1MemoryPool.hpp size_t G1MemoryPoolSuper::old_space_used(G1CollectedHeap* g1h) { - size_t used = overall_used(g1h); - size_t eden_used = eden_space_used(g1h); - size_t survivor_used = survivor_space_used(g1h); - used = subtract_up_to_zero(used, eden_used); - used = subtract_up_to_zero(used, survivor_used); - return used; + return g1h->g1mm()->old_space_used(); } G1EdenPool::G1EdenPool(G1CollectedHeap* g1h) :
--- a/src/share/vm/services/g1MemoryPool.hpp Wed Apr 20 20:32:45 2011 -0700 +++ b/src/share/vm/services/g1MemoryPool.hpp Fri Apr 22 09:26:09 2011 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -46,68 +46,9 @@ // get, as this does affect the performance and behavior of G1. Which // is why we introduce the three memory pools implemented here. // -// The above approach inroduces a couple of challenging issues in the -// implementation of the three memory pools: -// -// 1) The used space calculation for a pool is not necessarily -// independent of the others. We can easily get from G1 the overall -// used space in the entire heap, the number of regions in the young -// generation (includes both eden and survivors), and the number of -// survivor regions. So, from that we calculate: -// -// survivor_used = survivor_num * region_size -// eden_used = young_region_num * region_size - survivor_used -// old_gen_used = overall_used - eden_used - survivor_used -// -// Note that survivor_used and eden_used are upper bounds. To get the -// actual value we would have to iterate over the regions and add up -// ->used(). But that'd be expensive. So, we'll accept some lack of -// accuracy for those two. But, we have to be careful when calculating -// old_gen_used, in case we subtract from overall_used more then the -// actual number and our result goes negative. -// -// 2) Calculating the used space is straightforward, as described -// above. However, how do we calculate the committed space, given that -// we allocate space for the eden, survivor, and old gen out of the -// same pool of regions? One way to do this is to use the used value -// as also the committed value for the eden and survivor spaces and -// then calculate the old gen committed space as follows: -// -// old_gen_committed = overall_committed - eden_committed - survivor_committed +// See comments in g1MonitoringSupport.hpp for additional details +// on this model. // -// Maybe a better way to do that would be to calculate used for eden -// and survivor as a sum of ->used() over their regions and then -// calculate committed as region_num * region_size (i.e., what we use -// to calculate the used space now). This is something to consider -// in the future. -// -// 3) Another decision that is again not straightforward is what is -// the max size that each memory pool can grow to. One way to do this -// would be to use the committed size for the max for the eden and -// survivors and calculate the old gen max as follows (basically, it's -// a similar pattern to what we use for the committed space, as -// described above): -// -// old_gen_max = overall_max - eden_max - survivor_max -// -// Unfortunately, the above makes the max of each pool fluctuate over -// time and, even though this is allowed according to the spec, it -// broke several assumptions in the M&M framework (there were cases -// where used would reach a value greater than max). So, for max we -// use -1, which means "undefined" according to the spec. -// -// 4) Now, there is a very subtle issue with all the above. The -// framework will call get_memory_usage() on the three pools -// asynchronously. As a result, each call might get a different value -// for, say, survivor_num which will yield inconsistent values for -// eden_used, survivor_used, and old_gen_used (as survivor_num is used -// in the calculation of all three). This would normally be -// ok. However, it's possible that this might cause the sum of -// eden_used, survivor_used, and old_gen_used to go over the max heap -// size and this seems to sometimes cause JConsole (and maybe other -// clients) to get confused. There's not a really an easy / clean -// solution to this problem, due to the asynchrounous nature of the -// framework. // This class is shared by the three G1 memory pool classes @@ -116,22 +57,6 @@ // (see comment above), we put the calculations in this class so that // we can easily share them among the subclasses. class G1MemoryPoolSuper : public CollectedMemoryPool { -private: - // It returns x - y if x > y, 0 otherwise. - // As described in the comment above, some of the inputs to the - // calculations we have to do are obtained concurrently and hence - // may be inconsistent with each other. So, this provides a - // defensive way of performing the subtraction and avoids the value - // going negative (which would mean a very large result, given that - // the parameter are size_t). - static size_t subtract_up_to_zero(size_t x, size_t y) { - if (x > y) { - return x - y; - } else { - return 0; - } - } - protected: G1CollectedHeap* _g1h; @@ -148,13 +73,6 @@ return (size_t) -1; } - static size_t overall_committed(G1CollectedHeap* g1h) { - return g1h->capacity(); - } - static size_t overall_used(G1CollectedHeap* g1h) { - return g1h->used_unlocked(); - } - static size_t eden_space_committed(G1CollectedHeap* g1h); static size_t eden_space_used(G1CollectedHeap* g1h);