jdk8-mips64-public/hotspot: src/share/vm/gc_interface/collectedHeap.cpp@39b01ab7035a (annotated)

src/share/vm/gc_interface/collectedHeap.cpp@39b01ab7035a (annotated)

src/share/vm/gc_interface/collectedHeap.cpp

Fri, 16 Oct 2009 02:05:46 -0700

author: ysr
date: Fri, 16 Oct 2009 02:05:46 -0700
changeset 1462: 39b01ab7035a
parent 1063: 7bb995fbd3c0
child 1577: 4ce7240d622c
permissions: -rw-r--r--

6888898: CMS: ReduceInitialCardMarks unsafe in the presence of cms precleaning
6889757: G1: enable card mark elision for initializing writes from compiled code (ReduceInitialCardMarks)
Summary: Defer the (compiler-elided) card-mark upon a slow-path allocation until after the store and before the next subsequent safepoint; G1 now answers yes to can_elide_tlab_write_barriers().
Reviewed-by: jcoomes, kvn, never

 /*
  * Copyright 2001-2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 # include "incls/_precompiled.incl"
 # include "incls/_collectedHeap.cpp.incl"
 #ifdef ASSERT
 int CollectedHeap::_fire_out_of_memory_count = 0;
 #endif
 size_t CollectedHeap::_filler_array_max_size = 0;
 // Memory state functions.
 CollectedHeap::CollectedHeap()
 {
   const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
   const size_t elements_per_word = HeapWordSize / sizeof(jint);
   _filler_array_max_size = align_object_size(filler_array_hdr_size() +
                                              max_len * elements_per_word);
   _barrier_set = NULL;
   _is_gc_active = false;
   _total_collections = _total_full_collections = 0;
   _gc_cause = _gc_lastcause = GCCause::_no_gc;
   NOT_PRODUCT(_promotion_failure_alot_count = 0;)
   NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
   if (UsePerfData) {
     EXCEPTION_MARK;
     // create the gc cause jvmstat counters
     _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
 , GCCause::to_string(_gc_cause), CHECK);
     _perf_gc_lastcause =
                 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
 , GCCause::to_string(_gc_lastcause), CHECK);
   }
 }
 #ifndef PRODUCT
 void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) {
   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
     for (size_t slot = 0; slot < size; slot += 1) {
       assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
              "Found badHeapWordValue in post-allocation check");
     }
   }
 }
 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
  {
   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
     for (size_t slot = 0; slot < size; slot += 1) {
       assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal),
              "Found non badHeapWordValue in pre-allocation check");
     }
   }
 }
 #endif // PRODUCT
 #ifdef ASSERT
 void CollectedHeap::check_for_valid_allocation_state() {
   Thread *thread = Thread::current();
   // How to choose between a pending exception and a potential
   // OutOfMemoryError?  Don't allow pending exceptions.
   // This is a VM policy failure, so how do we exhaustively test it?
   assert(!thread->has_pending_exception(),
          "shouldn't be allocating with pending exception");
   if (StrictSafepointChecks) {
     assert(thread->allow_allocation(),
            "Allocation done by thread for which allocation is blocked "
            "by No_Allocation_Verifier!");
     // Allocation of an oop can always invoke a safepoint,
     // hence, the true argument
     thread->check_for_valid_safepoint_state(true);
   }
 }
 #endif
 HeapWord* CollectedHeap::allocate_from_tlab_slow(Thread* thread, size_t size) {
   // Retain tlab and allocate object in shared space if
   // the amount free in the tlab is too large to discard.
   if (thread->tlab().free() > thread->tlab().refill_waste_limit()) {
     thread->tlab().record_slow_allocation(size);
     return NULL;
   }
   // Discard tlab and allocate a new one.
   // To minimize fragmentation, the last TLAB may be smaller than the rest.
   size_t new_tlab_size = thread->tlab().compute_size(size);
   thread->tlab().clear_before_allocation();
   if (new_tlab_size == 0) {
     return NULL;
   }
   // Allocate a new TLAB...
   HeapWord* obj = Universe::heap()->allocate_new_tlab(new_tlab_size);
   if (obj == NULL) {
     return NULL;
   }
   if (ZeroTLAB) {
     // ..and clear it.
     Copy::zero_to_words(obj, new_tlab_size);
   } else {
     // ...and clear just the allocated object.
     Copy::zero_to_words(obj, size);
   }
   thread->tlab().fill(obj, obj + size, new_tlab_size);
   return obj;
 }
 void CollectedHeap::flush_deferred_store_barrier(JavaThread* thread) {
   MemRegion deferred = thread->deferred_card_mark();
   if (!deferred.is_empty()) {
     {
       // Verify that the storage points to a parsable object in heap
       DEBUG_ONLY(oop old_obj = oop(deferred.start());)
       assert(is_in(old_obj), "Not in allocated heap");
       assert(!can_elide_initializing_store_barrier(old_obj),
              "Else should have been filtered in defer_store_barrier()");
       assert(!is_in_permanent(old_obj), "Sanity: not expected");
       assert(old_obj->is_oop(true), "Not an oop");
       assert(old_obj->is_parsable(), "Will not be concurrently parsable");
       assert(deferred.word_size() == (size_t)(old_obj->size()),
              "Mismatch: multiple objects?");
     }
     BarrierSet* bs = barrier_set();
     assert(bs->has_write_region_opt(), "No write_region() on BarrierSet");
     bs->write_region(deferred);
     // "Clear" the deferred_card_mark field
     thread->set_deferred_card_mark(MemRegion());
   }
   assert(thread->deferred_card_mark().is_empty(), "invariant");
 }
 // Helper for ReduceInitialCardMarks. For performance,
 // compiled code may elide card-marks for initializing stores
 // to a newly allocated object along the fast-path. We
 // compensate for such elided card-marks as follows:
 // (a) Generational, non-concurrent collectors, such as
 //     GenCollectedHeap(ParNew,DefNew,Tenured) and
 //     ParallelScavengeHeap(ParallelGC, ParallelOldGC)
 //     need the card-mark if and only if the region is
 //     in the old gen, and do not care if the card-mark
 //     succeeds or precedes the initializing stores themselves,
 //     so long as the card-mark is completed before the next
 //     scavenge. For all these cases, we can do a card mark
 //     at the point at which we do a slow path allocation
 //     in the old gen. For uniformity, however, we end
 //     up using the same scheme (see below) for all three
 //     cases (deferring the card-mark appropriately).
 // (b) GenCollectedHeap(ConcurrentMarkSweepGeneration) requires
 //     in addition that the card-mark for an old gen allocated
 //     object strictly follow any associated initializing stores.
 //     In these cases, the memRegion remembered below is
 //     used to card-mark the entire region either just before the next
 //     slow-path allocation by this thread or just before the next scavenge or
 //     CMS-associated safepoint, whichever of these events happens first.
 //     (The implicit assumption is that the object has been fully
 //     initialized by this point, a fact that we assert when doing the
 //     card-mark.)
 // (c) G1CollectedHeap(G1) uses two kinds of write barriers. When a
 //     G1 concurrent marking is in progress an SATB (pre-write-)barrier is
 //     is used to remember the pre-value of any store. Initializing
 //     stores will not need this barrier, so we need not worry about
 //     compensating for the missing pre-barrier here. Turning now
 //     to the post-barrier, we note that G1 needs a RS update barrier
 //     which simply enqueues a (sequence of) dirty cards which may
 //     optionally be refined by the concurrent update threads. Note
 //     that this barrier need only be applied to a non-young write,
 //     but, like in CMS, because of the presence of concurrent refinement
 //     (much like CMS' precleaning), must strictly follow the oop-store.
 //     Thus, using the same protocol for maintaining the intended
 //     invariants turns out, serendepitously, to be the same for all
 //     three collectors/heap types above.
 //
 // For each future collector, this should be reexamined with
 // that specific collector in mind.
 oop CollectedHeap::defer_store_barrier(JavaThread* thread, oop new_obj) {
   // If a previous card-mark was deferred, flush it now.
   flush_deferred_store_barrier(thread);
   if (can_elide_initializing_store_barrier(new_obj)) {
     // The deferred_card_mark region should be empty
     // following the flush above.
     assert(thread->deferred_card_mark().is_empty(), "Error");
   } else {
     // Remember info for the newly deferred store barrier
     MemRegion deferred = MemRegion((HeapWord*)new_obj, new_obj->size());
     assert(!deferred.is_empty(), "Error");
     thread->set_deferred_card_mark(deferred);
   }
   return new_obj;
 }
 size_t CollectedHeap::filler_array_hdr_size() {
   return size_t(arrayOopDesc::header_size(T_INT));
 }
 size_t CollectedHeap::filler_array_min_size() {
   return align_object_size(filler_array_hdr_size());
 }
 size_t CollectedHeap::filler_array_max_size() {
   return _filler_array_max_size;
 }
 #ifdef ASSERT
 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
 {
   assert(words >= min_fill_size(), "too small to fill");
   assert(words % MinObjAlignment == 0, "unaligned size");
   assert(Universe::heap()->is_in_reserved(start), "not in heap");
   assert(Universe::heap()->is_in_reserved(start + words - 1), "not in heap");
 }
 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words)
 {
   if (ZapFillerObjects) {
     Copy::fill_to_words(start + filler_array_hdr_size(),
                         words - filler_array_hdr_size(), 0XDEAFBABE);
   }
 }
 #endif // ASSERT
 void
 CollectedHeap::fill_with_array(HeapWord* start, size_t words)
 {
   assert(words >= filler_array_min_size(), "too small for an array");
   assert(words <= filler_array_max_size(), "too big for a single object");
   const size_t payload_size = words - filler_array_hdr_size();
   const size_t len = payload_size * HeapWordSize / sizeof(jint);
   // Set the length first for concurrent GC.
   ((arrayOop)start)->set_length((int)len);
   post_allocation_setup_common(Universe::intArrayKlassObj(), start, words);
   DEBUG_ONLY(zap_filler_array(start, words);)
 }
 void
 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words)
 {
   assert(words <= filler_array_max_size(), "too big for a single object");
   if (words >= filler_array_min_size()) {
     fill_with_array(start, words);
   } else if (words > 0) {
     assert(words == min_fill_size(), "unaligned size");
     post_allocation_setup_common(SystemDictionary::object_klass(), start,
                                  words);
   }
 }
 void CollectedHeap::fill_with_object(HeapWord* start, size_t words)
 {
   DEBUG_ONLY(fill_args_check(start, words);)
   HandleMark hm;  // Free handles before leaving.
   fill_with_object_impl(start, words);
 }
 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words)
 {
   DEBUG_ONLY(fill_args_check(start, words);)
   HandleMark hm;  // Free handles before leaving.
 #ifdef LP64
   // A single array can fill ~8G, so multiple objects are needed only in 64-bit.
   // First fill with arrays, ensuring that any remaining space is big enough to
   // fill.  The remainder is filled with a single object.
   const size_t min = min_fill_size();
   const size_t max = filler_array_max_size();
   while (words > max) {
     const size_t cur = words - max >= min ? max : max - min;
     fill_with_array(start, cur);
     start += cur;
     words -= cur;
   }
 #endif
   fill_with_object_impl(start, words);
 }
 HeapWord* CollectedHeap::allocate_new_tlab(size_t size) {
   guarantee(false, "thread-local allocation buffers not supported");
   return NULL;
 }
 void CollectedHeap::fill_all_tlabs(bool retire) {
   assert(UseTLAB, "should not reach here");
   // See note in ensure_parsability() below.
   assert(SafepointSynchronize::is_at_safepoint() ||
          !is_init_completed(),
          "should only fill tlabs at safepoint");
   // The main thread starts allocating via a TLAB even before it
   // has added itself to the threads list at vm boot-up.
   assert(Threads::first() != NULL,
          "Attempt to fill tlabs before main thread has been added"
          " to threads list is doomed to failure!");
   for(JavaThread *thread = Threads::first(); thread; thread = thread->next()) {
      thread->tlab().make_parsable(retire);
   }
 }
 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
   // The second disjunct in the assertion below makes a concession
   // for the start-up verification done while the VM is being
   // created. Callers be careful that you know that mutators
   // aren't going to interfere -- for instance, this is permissible
   // if we are still single-threaded and have either not yet
   // started allocating (nothing much to verify) or we have
   // started allocating but are now a full-fledged JavaThread
   // (and have thus made our TLAB's) available for filling.
   assert(SafepointSynchronize::is_at_safepoint() ||
          !is_init_completed(),
          "Should only be called at a safepoint or at start-up"
          " otherwise concurrent mutator activity may make heap "
          " unparsable again");
   if (UseTLAB) {
     fill_all_tlabs(retire_tlabs);
   }
 }
 void CollectedHeap::accumulate_statistics_all_tlabs() {
   if (UseTLAB) {
     assert(SafepointSynchronize::is_at_safepoint() ||
          !is_init_completed(),
          "should only accumulate statistics on tlabs at safepoint");
     ThreadLocalAllocBuffer::accumulate_statistics_before_gc();
   }
 }
 void CollectedHeap::resize_all_tlabs() {
   if (UseTLAB) {
     assert(SafepointSynchronize::is_at_safepoint() ||
          !is_init_completed(),
          "should only resize tlabs at safepoint");
     ThreadLocalAllocBuffer::resize_all_tlabs();
   }
 }
 void CollectedHeap::pre_full_gc_dump() {
   if (HeapDumpBeforeFullGC) {
     TraceTime tt("Heap Dump: ", PrintGCDetails, false, gclog_or_tty);
     // We are doing a "major" collection and a heap dump before
     // major collection has been requested.
     HeapDumper::dump_heap();
   }
   if (PrintClassHistogramBeforeFullGC) {
     TraceTime tt("Class Histogram: ", PrintGCDetails, true, gclog_or_tty);
     VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */, false /* ! prologue */);
     inspector.doit();
   }
 }
 void CollectedHeap::post_full_gc_dump() {
   if (HeapDumpAfterFullGC) {
     TraceTime tt("Heap Dump", PrintGCDetails, false, gclog_or_tty);
     HeapDumper::dump_heap();
   }
   if (PrintClassHistogramAfterFullGC) {
     TraceTime tt("Class Histogram", PrintGCDetails, true, gclog_or_tty);
     VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */, false /* ! prologue */);
     inspector.doit();
   }
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_interface/collectedHeap.cpp@39b01ab7035a (annotated)

src/share/vm/gc_interface/collectedHeap.cpp