jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp@d30fa85f9994 (annotated)

src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp@d30fa85f9994 (annotated)

src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp

Thu, 12 Jan 2012 00:06:47 -0800

author: johnc
date: Thu, 12 Jan 2012 00:06:47 -0800
changeset 3463: d30fa85f9994
parent 2716: c84ee870e0b9
child 3900: d2a62e0f25eb
child 3923: 922993931b3d
permissions: -rw-r--r--

6484965: G1: piggy-back liveness accounting phase on marking
Summary: Remove the separate counting phase of concurrent marking by tracking the amount of marked bytes and the cards spanned by marked objects in marking task/worker thread local data structures, which are updated as individual objects are marked.
Reviewed-by: brutisso, tonyp

 /*
  * 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
  * 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/concurrentG1Refine.hpp"
 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
 #include "gc_implementation/g1/g1RemSet.hpp"
 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
 #include "memory/space.inline.hpp"
 #include "runtime/atomic.hpp"
 #include "runtime/java.hpp"
 #include "utilities/copy.hpp"
 // Possible sizes for the card counts cache: odd primes that roughly double in size.
 // (See jvmtiTagMap.cpp).
 #define MAX_SIZE ((size_t) -1)
 size_t ConcurrentG1Refine::_cc_cache_sizes[] = {
 ,    32771,    76831,    150001,   307261,
 ,  1228891,  2457733,   4915219,  9830479,
        19660831, 39321619, 78643219, 157286461,  MAX_SIZE
   };
 ConcurrentG1Refine::ConcurrentG1Refine() :
   _card_counts(NULL), _card_epochs(NULL),
   _n_card_counts(0), _max_cards(0), _max_n_card_counts(0),
   _cache_size_index(0), _expand_card_counts(false),
   _hot_cache(NULL),
   _def_use_cache(false), _use_cache(false),
   // We initialize the epochs of the array to 0. By initializing
   // _n_periods to 1 and not 0 we automatically invalidate all the
   // entries on the array. Otherwise we might accidentally think that
   // we claimed a card that was in fact never set (see CR7033292).
   _n_periods(1),
   _threads(NULL), _n_threads(0)
 {
   // Ergomonically select initial concurrent refinement parameters
   if (FLAG_IS_DEFAULT(G1ConcRefinementGreenZone)) {
     FLAG_SET_DEFAULT(G1ConcRefinementGreenZone, MAX2<int>(ParallelGCThreads, 1));
   }
   set_green_zone(G1ConcRefinementGreenZone);
   if (FLAG_IS_DEFAULT(G1ConcRefinementYellowZone)) {
     FLAG_SET_DEFAULT(G1ConcRefinementYellowZone, green_zone() * 3);
   }
   set_yellow_zone(MAX2<int>(G1ConcRefinementYellowZone, green_zone()));
   if (FLAG_IS_DEFAULT(G1ConcRefinementRedZone)) {
     FLAG_SET_DEFAULT(G1ConcRefinementRedZone, yellow_zone() * 2);
   }
   set_red_zone(MAX2<int>(G1ConcRefinementRedZone, yellow_zone()));
   _n_worker_threads = thread_num();
   // We need one extra thread to do the young gen rset size sampling.
   _n_threads = _n_worker_threads + 1;
   reset_threshold_step();
   _threads = NEW_C_HEAP_ARRAY(ConcurrentG1RefineThread*, _n_threads);
   int worker_id_offset = (int)DirtyCardQueueSet::num_par_ids();
   ConcurrentG1RefineThread *next = NULL;
   for (int i = _n_threads - 1; i >= 0; i--) {
     ConcurrentG1RefineThread* t = new ConcurrentG1RefineThread(this, next, worker_id_offset, i);
     assert(t != NULL, "Conc refine should have been created");
     assert(t->cg1r() == this, "Conc refine thread should refer to this");
     _threads[i] = t;
     next = t;
   }
 }
 void ConcurrentG1Refine::reset_threshold_step() {
   if (FLAG_IS_DEFAULT(G1ConcRefinementThresholdStep)) {
     _thread_threshold_step = (yellow_zone() - green_zone()) / (worker_thread_num() + 1);
   } else {
     _thread_threshold_step = G1ConcRefinementThresholdStep;
   }
 }
 int ConcurrentG1Refine::thread_num() {
   return MAX2<int>((G1ConcRefinementThreads > 0) ? G1ConcRefinementThreads : ParallelGCThreads, 1);
 }
 void ConcurrentG1Refine::init() {
   if (G1ConcRSLogCacheSize > 0) {
     _g1h = G1CollectedHeap::heap();
     _max_cards = _g1h->max_capacity() >> CardTableModRefBS::card_shift;
     _max_n_card_counts = _max_cards * G1MaxHotCardCountSizePercent / 100;
     size_t max_card_num = ((size_t)1 << (sizeof(unsigned)*BitsPerByte-1)) - 1;
     guarantee(_max_cards < max_card_num, "card_num representation");
     // We need _n_card_counts to be less than _max_n_card_counts here
     // so that the expansion call (below) actually allocates the
     // _counts and _epochs arrays.
     assert(_n_card_counts == 0, "pre-condition");
     assert(_max_n_card_counts > 0, "pre-condition");
     // Find the index into cache size array that is of a size that's
     // large enough to hold desired_sz.
     size_t desired_sz = _max_cards / InitialCacheFraction;
     int desired_sz_index = 0;
     while (_cc_cache_sizes[desired_sz_index] < desired_sz) {
       desired_sz_index += 1;
       assert(desired_sz_index <  MAX_CC_CACHE_INDEX, "invariant");
     }
     assert(desired_sz_index <  MAX_CC_CACHE_INDEX, "invariant");
     // If the desired_sz value is between two sizes then
     // _cc_cache_sizes[desired_sz_index-1] < desired_sz <= _cc_cache_sizes[desired_sz_index]
     // we will start with the lower size in the optimistic expectation that
     // we will not need to expand up. Note desired_sz_index could also be 0.
     if (desired_sz_index > 0 &&
         _cc_cache_sizes[desired_sz_index] > desired_sz) {
       desired_sz_index -= 1;
     }
     if (!expand_card_count_cache(desired_sz_index)) {
       // Allocation was unsuccessful - exit
       vm_exit_during_initialization("Could not reserve enough space for card count cache");
     }
     assert(_n_card_counts > 0, "post-condition");
     assert(_cache_size_index == desired_sz_index, "post-condition");
     Copy::fill_to_bytes(&_card_counts[0],
                         _n_card_counts * sizeof(CardCountCacheEntry));
     Copy::fill_to_bytes(&_card_epochs[0], _n_card_counts * sizeof(CardEpochCacheEntry));
     ModRefBarrierSet* bs = _g1h->mr_bs();
     guarantee(bs->is_a(BarrierSet::CardTableModRef), "Precondition");
     _ct_bs = (CardTableModRefBS*)bs;
     _ct_bot = _ct_bs->byte_for_const(_g1h->reserved_region().start());
     _def_use_cache = true;
     _use_cache = true;
     _hot_cache_size = (1 << G1ConcRSLogCacheSize);
     _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size);
     _n_hot = 0;
     _hot_cache_idx = 0;
     // For refining the cards in the hot cache in parallel
     int n_workers = (ParallelGCThreads > 0 ?
                         _g1h->workers()->total_workers() : 1);
     _hot_cache_par_chunk_size = MAX2(1, _hot_cache_size / n_workers);
     _hot_cache_par_claimed_idx = 0;
   }
 }
 void ConcurrentG1Refine::stop() {
   if (_threads != NULL) {
     for (int i = 0; i < _n_threads; i++) {
       _threads[i]->stop();
     }
   }
 }
 void ConcurrentG1Refine::reinitialize_threads() {
   reset_threshold_step();
   if (_threads != NULL) {
     for (int i = 0; i < _n_threads; i++) {
       _threads[i]->initialize();
     }
   }
 }
 ConcurrentG1Refine::~ConcurrentG1Refine() {
   if (G1ConcRSLogCacheSize > 0) {
     // Please see the comment in allocate_card_count_cache
     // for why we call os::malloc() and os::free() directly.
     assert(_card_counts != NULL, "Logic");
     os::free(_card_counts);
     assert(_card_epochs != NULL, "Logic");
     os::free(_card_epochs);
     assert(_hot_cache != NULL, "Logic");
     FREE_C_HEAP_ARRAY(jbyte*, _hot_cache);
   }
   if (_threads != NULL) {
     for (int i = 0; i < _n_threads; i++) {
       delete _threads[i];
     }
     FREE_C_HEAP_ARRAY(ConcurrentG1RefineThread*, _threads);
   }
 }
 void ConcurrentG1Refine::threads_do(ThreadClosure *tc) {
   if (_threads != NULL) {
     for (int i = 0; i < _n_threads; i++) {
       tc->do_thread(_threads[i]);
     }
   }
 }
 bool ConcurrentG1Refine::is_young_card(jbyte* card_ptr) {
   HeapWord* start = _ct_bs->addr_for(card_ptr);
   HeapRegion* r = _g1h->heap_region_containing(start);
   if (r != NULL && r->is_young()) {
     return true;
   }
   // This card is not associated with a heap region
   // so can't be young.
   return false;
 }
 jbyte* ConcurrentG1Refine::add_card_count(jbyte* card_ptr, int* count, bool* defer) {
   unsigned new_card_num = ptr_2_card_num(card_ptr);
   unsigned bucket = hash(new_card_num);
   assert(0 <= bucket && bucket < _n_card_counts, "Bounds");
   CardCountCacheEntry* count_ptr = &_card_counts[bucket];
   CardEpochCacheEntry* epoch_ptr = &_card_epochs[bucket];
   // We have to construct a new entry if we haven't updated the counts
   // during the current period, or if the count was updated for a
   // different card number.
   unsigned int new_epoch = (unsigned int) _n_periods;
   julong new_epoch_entry = make_epoch_entry(new_card_num, new_epoch);
   while (true) {
     // Fetch the previous epoch value
     julong prev_epoch_entry = epoch_ptr->_value;
     julong cas_res;
     if (extract_epoch(prev_epoch_entry) != new_epoch) {
       // This entry has not yet been updated during this period.
       // Note: we update the epoch value atomically to ensure
       // that there is only one winner that updates the cached
       // card_ptr value even though all the refine threads share
       // the same epoch value.
       cas_res = (julong) Atomic::cmpxchg((jlong) new_epoch_entry,
                                          (volatile jlong*)&epoch_ptr->_value,
                                          (jlong) prev_epoch_entry);
       if (cas_res == prev_epoch_entry) {
         // We have successfully won the race to update the
         // epoch and card_num value. Make it look like the
         // count and eviction count were previously cleared.
         count_ptr->_count = 1;
         count_ptr->_evict_count = 0;
         *count = 0;
         // We can defer the processing of card_ptr
         *defer = true;
         return card_ptr;
       }
       // We did not win the race to update the epoch field, so some other
       // thread must have done it. The value that gets returned by CAS
       // should be the new epoch value.
       assert(extract_epoch(cas_res) == new_epoch, "unexpected epoch");
       // We could 'continue' here or just re-read the previous epoch value
       prev_epoch_entry = epoch_ptr->_value;
     }
     // The epoch entry for card_ptr has been updated during this period.
     unsigned old_card_num = extract_card_num(prev_epoch_entry);
     // The card count that will be returned to caller
     *count = count_ptr->_count;
     // Are we updating the count for the same card?
     if (new_card_num == old_card_num) {
       // Same card - just update the count. We could have more than one
       // thread racing to update count for the current card. It should be
       // OK not to use a CAS as the only penalty should be some missed
       // increments of the count which delays identifying the card as "hot".
       if (*count < max_jubyte) count_ptr->_count++;
       // We can defer the processing of card_ptr
       *defer = true;
       return card_ptr;
     }
     // Different card - evict old card info
     if (count_ptr->_evict_count < max_jubyte) count_ptr->_evict_count++;
     if (count_ptr->_evict_count > G1CardCountCacheExpandThreshold) {
       // Trigger a resize the next time we clear
       _expand_card_counts = true;
     }
     cas_res = (julong) Atomic::cmpxchg((jlong) new_epoch_entry,
                                        (volatile jlong*)&epoch_ptr->_value,
                                        (jlong) prev_epoch_entry);
     if (cas_res == prev_epoch_entry) {
       // We successfully updated the card num value in the epoch entry
       count_ptr->_count = 0; // initialize counter for new card num
       jbyte* old_card_ptr = card_num_2_ptr(old_card_num);
       // Even though the region containg the card at old_card_num was not
       // in the young list when old_card_num was recorded in the epoch
       // cache it could have been added to the free list and subsequently
       // added to the young list in the intervening time. See CR 6817995.
       // We do not deal with this case here - it will be handled in
       // HeapRegion::oops_on_card_seq_iterate_careful after it has been
       // determined that the region containing the card has been allocated
       // to, and it's safe to check the young type of the region.
       // We do not want to defer processing of card_ptr in this case
       // (we need to refine old_card_ptr and card_ptr)
       *defer = false;
       return old_card_ptr;
     }
     // Someone else beat us - try again.
   }
 }
 jbyte* ConcurrentG1Refine::cache_insert(jbyte* card_ptr, bool* defer) {
   int count;
   jbyte* cached_ptr = add_card_count(card_ptr, &count, defer);
   assert(cached_ptr != NULL, "bad cached card ptr");
   // We've just inserted a card pointer into the card count cache
   // and got back the card that we just inserted or (evicted) the
   // previous contents of that count slot.
   // The card we got back could be in a young region. When the
   // returned card (if evicted) was originally inserted, we had
   // determined that its containing region was not young. However
   // it is possible for the region to be freed during a cleanup
   // pause, then reallocated and tagged as young which will result
   // in the returned card residing in a young region.
   //
   // We do not deal with this case here - the change from non-young
   // to young could be observed at any time - it will be handled in
   // HeapRegion::oops_on_card_seq_iterate_careful after it has been
   // determined that the region containing the card has been allocated
   // to.
   // The card pointer we obtained from card count cache is not hot
   // so do not store it in the cache; return it for immediate
   // refining.
   if (count < G1ConcRSHotCardLimit) {
     return cached_ptr;
   }
   // Otherwise, the pointer we got from the _card_counts cache is hot.
   jbyte* res = NULL;
   MutexLockerEx x(HotCardCache_lock, Mutex::_no_safepoint_check_flag);
   if (_n_hot == _hot_cache_size) {
     res = _hot_cache[_hot_cache_idx];
     _n_hot--;
   }
   // Now _n_hot < _hot_cache_size, and we can insert at _hot_cache_idx.
   _hot_cache[_hot_cache_idx] = cached_ptr;
   _hot_cache_idx++;
   if (_hot_cache_idx == _hot_cache_size) _hot_cache_idx = 0;
   _n_hot++;
   // The card obtained from the hot card cache could be in a young
   // region. See above on how this can happen.
   return res;
 }
 void ConcurrentG1Refine::clean_up_cache(int worker_i,
                                         G1RemSet* g1rs,
                                         DirtyCardQueue* into_cset_dcq) {
   assert(!use_cache(), "cache should be disabled");
   int start_idx;
   while ((start_idx = _hot_cache_par_claimed_idx) < _n_hot) { // read once
     int end_idx = start_idx + _hot_cache_par_chunk_size;
     if (start_idx ==
         Atomic::cmpxchg(end_idx, &_hot_cache_par_claimed_idx, start_idx)) {
       // The current worker has successfully claimed the chunk [start_idx..end_idx)
       end_idx = MIN2(end_idx, _n_hot);
       for (int i = start_idx; i < end_idx; i++) {
         jbyte* entry = _hot_cache[i];
         if (entry != NULL) {
           if (g1rs->concurrentRefineOneCard(entry, worker_i, true)) {
             // 'entry' contains references that point into the current
             // collection set. We need to record 'entry' in the DCQS
             // that's used for that purpose.
             //
             // The only time we care about recording cards that contain
             // references that point into the collection set is during
             // RSet updating while within an evacuation pause.
             // In this case worker_i should be the id of a GC worker thread
             assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause");
             assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads), "incorrect worker id");
             into_cset_dcq->enqueue(entry);
           }
         }
       }
     }
   }
 }
 // The arrays used to hold the card counts and the epochs must have
 // a 1:1 correspondence. Hence they are allocated and freed together
 // Returns true if the allocations of both the counts and epochs
 // were successful; false otherwise.
 bool ConcurrentG1Refine::allocate_card_count_cache(size_t n,
                                                    CardCountCacheEntry** counts,
                                                    CardEpochCacheEntry** epochs) {
   // We call the allocation/free routines directly for the counts
   // and epochs arrays. The NEW_C_HEAP_ARRAY/FREE_C_HEAP_ARRAY
   // macros call AllocateHeap and FreeHeap respectively.
   // AllocateHeap will call vm_exit_out_of_memory in the event
   // of an allocation failure and abort the JVM. With the
   // _counts/epochs arrays we only need to abort the JVM if the
   // initial allocation of these arrays fails.
   //
   // Additionally AllocateHeap/FreeHeap do some tracing of
   // allocate/free calls so calling one without calling the
   // other can cause inconsistencies in the tracing. So we
   // call neither.
   assert(*counts == NULL, "out param");
   assert(*epochs == NULL, "out param");
   size_t counts_size = n * sizeof(CardCountCacheEntry);
   size_t epochs_size = n * sizeof(CardEpochCacheEntry);
   *counts = (CardCountCacheEntry*) os::malloc(counts_size);
   if (*counts == NULL) {
     // allocation was unsuccessful
     return false;
   }
   *epochs = (CardEpochCacheEntry*) os::malloc(epochs_size);
   if (*epochs == NULL) {
     // allocation was unsuccessful - free counts array
     assert(*counts != NULL, "must be");
     os::free(*counts);
     *counts = NULL;
     return false;
   }
   // We successfully allocated both counts and epochs
   return true;
 }
 // Returns true if the card counts/epochs cache was
 // successfully expanded; false otherwise.
 bool ConcurrentG1Refine::expand_card_count_cache(int cache_size_idx) {
   // Can we expand the card count and epoch tables?
   if (_n_card_counts < _max_n_card_counts) {
     assert(cache_size_idx >= 0 && cache_size_idx  < MAX_CC_CACHE_INDEX, "oob");
     size_t cache_size = _cc_cache_sizes[cache_size_idx];
     // Make sure we don't go bigger than we will ever need
     cache_size = MIN2(cache_size, _max_n_card_counts);
     // Should we expand the card count and card epoch tables?
     if (cache_size > _n_card_counts) {
       // We have been asked to allocate new, larger, arrays for
       // the card counts and the epochs. Attempt the allocation
       // of both before we free the existing arrays in case
       // the allocation is unsuccessful...
       CardCountCacheEntry* counts = NULL;
       CardEpochCacheEntry* epochs = NULL;
       if (allocate_card_count_cache(cache_size, &counts, &epochs)) {
         // Allocation was successful.
         // We can just free the old arrays; we're
         // not interested in preserving the contents
         if (_card_counts != NULL) os::free(_card_counts);
         if (_card_epochs != NULL) os::free(_card_epochs);
         // Cache the size of the arrays and the index that got us there.
         _n_card_counts = cache_size;
         _cache_size_index = cache_size_idx;
         _card_counts = counts;
         _card_epochs = epochs;
         // We successfully allocated/expanded the caches.
         return true;
       }
     }
   }
   // We did not successfully expand the caches.
   return false;
 }
 void ConcurrentG1Refine::clear_and_record_card_counts() {
   if (G1ConcRSLogCacheSize == 0) return;
 #ifndef PRODUCT
   double start = os::elapsedTime();
 #endif
   if (_expand_card_counts) {
     int new_idx = _cache_size_index + 1;
     if (expand_card_count_cache(new_idx)) {
       // Allocation was successful and  _n_card_counts has
       // been updated to the new size. We only need to clear
       // the epochs so we don't read a bogus epoch value
       // when inserting a card into the hot card cache.
       Copy::fill_to_bytes(&_card_epochs[0], _n_card_counts * sizeof(CardEpochCacheEntry));
     }
     _expand_card_counts = false;
   }
   int this_epoch = (int) _n_periods;
   assert((this_epoch+1) <= max_jint, "to many periods");
   // Update epoch
   _n_periods++;
 #ifndef PRODUCT
   double elapsed = os::elapsedTime() - start;
   _g1h->g1_policy()->record_cc_clear_time(elapsed * 1000.0);
 #endif
 }
 void ConcurrentG1Refine::print_worker_threads_on(outputStream* st) const {
   for (int i = 0; i < _n_threads; ++i) {
     _threads[i]->print_on(st);
     st->cr();
   }
 }

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src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp@d30fa85f9994 (annotated)

src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp