jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1CardCounts.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1CardCounts.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1CardCounts.cpp

Fri, 10 Oct 2014 15:51:58 +0200

author: tschatzl
date: Fri, 10 Oct 2014 15:51:58 +0200
changeset 7257: e7d0505c8a30
parent 7051: 1f1d373cd044
child 7535: 7ae4e26cb1e0
child 9327: f96fcd9e1e1b
permissions: -rw-r--r--

8059758: Footprint regressions with JDK-8038423
Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything.
Reviewed-by: jwilhelm, brutisso

 /*
  * Copyright (c) 2013, 2014, 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/g1CardCounts.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
 #include "memory/cardTableModRefBS.hpp"
 #include "services/memTracker.hpp"
 #include "utilities/copy.hpp"
 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 void G1CardCountsMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
   if (zero_filled) {
     return;
   }
   MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);
   _counts->clear_range(mr);
 }
 void G1CardCounts::clear_range(size_t from_card_num, size_t to_card_num) {
   if (has_count_table()) {
     assert(from_card_num < to_card_num,
            err_msg("Wrong order? from: " SIZE_FORMAT ", to: "SIZE_FORMAT,
                    from_card_num, to_card_num));
     Copy::fill_to_bytes(&_card_counts[from_card_num], (to_card_num - from_card_num));
   }
 }
 G1CardCounts::G1CardCounts(G1CollectedHeap *g1h):
   _listener(), _g1h(g1h), _card_counts(NULL), _reserved_max_card_num(0) {
   _listener.set_cardcounts(this);
 }
 void G1CardCounts::initialize(G1RegionToSpaceMapper* mapper) {
   assert(_g1h->max_capacity() > 0, "initialization order");
   assert(_g1h->capacity() == 0, "initialization order");
   if (G1ConcRSHotCardLimit > 0) {
     // The max value we can store in the counts table is
     // max_jubyte. Guarantee the value of the hot
     // threshold limit is no more than this.
     guarantee(G1ConcRSHotCardLimit <= max_jubyte, "sanity");
     _ct_bs = _g1h->g1_barrier_set();
     _ct_bot = _ct_bs->byte_for_const(_g1h->reserved_region().start());
     _card_counts = (jubyte*) mapper->reserved().start();
     _reserved_max_card_num = mapper->reserved().byte_size();
     mapper->set_mapping_changed_listener(&_listener);
   }
 }
 uint G1CardCounts::add_card_count(jbyte* card_ptr) {
   // Returns the number of times the card has been refined.
   // If we failed to reserve/commit the counts table, return 0.
   // If card_ptr is beyond the committed end of the counts table,
   // return 0.
   // Otherwise return the actual count.
   // Unless G1ConcRSHotCardLimit has been set appropriately,
   // returning 0 will result in the card being considered
   // cold and will be refined immediately.
   uint count = 0;
   if (has_count_table()) {
     size_t card_num = ptr_2_card_num(card_ptr);
     assert(card_num < _reserved_max_card_num,
            err_msg("Card "SIZE_FORMAT" outside of card counts table (max size "SIZE_FORMAT")",
                    card_num, _reserved_max_card_num));
     count = (uint) _card_counts[card_num];
     if (count < G1ConcRSHotCardLimit) {
       _card_counts[card_num] =
         (jubyte)(MIN2((uintx)(_card_counts[card_num] + 1), G1ConcRSHotCardLimit));
     }
   }
   return count;
 }
 bool G1CardCounts::is_hot(uint count) {
   return (count >= G1ConcRSHotCardLimit);
 }
 void G1CardCounts::clear_region(HeapRegion* hr) {
   MemRegion mr(hr->bottom(), hr->end());
   clear_range(mr);
 }
 void G1CardCounts::clear_range(MemRegion mr) {
   if (has_count_table()) {
     const jbyte* from_card_ptr = _ct_bs->byte_for_const(mr.start());
     // We use the last address in the range as the range could represent the
     // last region in the heap. In which case trying to find the card will be an
     // OOB access to the card table.
     const jbyte* last_card_ptr = _ct_bs->byte_for_const(mr.last());
 #ifdef ASSERT
     HeapWord* start_addr = _ct_bs->addr_for(from_card_ptr);
     assert(start_addr == mr.start(), "MemRegion start must be aligned to a card.");
     HeapWord* last_addr = _ct_bs->addr_for(last_card_ptr);
     assert((last_addr + CardTableModRefBS::card_size_in_words) == mr.end(), "MemRegion end must be aligned to a card.");
 #endif // ASSERT
     // Clear the counts for the (exclusive) card range.
     size_t from_card_num = ptr_2_card_num(from_card_ptr);
     size_t to_card_num = ptr_2_card_num(last_card_ptr) + 1;
     clear_range(from_card_num, to_card_num);
   }
 }
 class G1CardCountsClearClosure : public HeapRegionClosure {
  private:
   G1CardCounts* _card_counts;
  public:
   G1CardCountsClearClosure(G1CardCounts* card_counts) :
     HeapRegionClosure(), _card_counts(card_counts) { }
   virtual bool doHeapRegion(HeapRegion* r) {
     _card_counts->clear_region(r);
     return false;
   }
 };
 void G1CardCounts::clear_all() {
   assert(SafepointSynchronize::is_at_safepoint(), "don't call this otherwise");
   G1CardCountsClearClosure cl(this);
   _g1h->heap_region_iterate(&cl);
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1CardCounts.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1CardCounts.cpp