jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/collectionSetChooser.cpp@5baec2e69518 (annotated)

src/share/vm/gc_implementation/g1/collectionSetChooser.cpp@5baec2e69518 (annotated)

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

Tue, 25 Sep 2012 07:05:55 -0700

author: jmasa
date: Tue, 25 Sep 2012 07:05:55 -0700
changeset 4097: 5baec2e69518
parent 3714: f7a8920427a6
child 4385: 37f7535e5f18
permissions: -rw-r--r--

7200615: NPG: optimized VM build is broken
Reviewed-by: kvn

 /*
  * Copyright (c) 2001, 2012, 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/collectionSetChooser.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
 #include "memory/space.inline.hpp"
 // Even though we don't use the GC efficiency in our heuristics as
 // much as we used to, we still order according to GC efficiency. This
 // will cause regions with a lot of live objects and large RSets to
 // end up at the end of the array. Given that we might skip collecting
 // the last few old regions, if after a few mixed GCs the remaining
 // have reclaimable bytes under a certain threshold, the hope is that
 // the ones we'll skip are ones with both large RSets and a lot of
 // live objects, not the ones with just a lot of live objects if we
 // ordered according to the amount of reclaimable bytes per region.
 static int order_regions(HeapRegion* hr1, HeapRegion* hr2) {
   if (hr1 == NULL) {
     if (hr2 == NULL) {
       return 0;
     } else {
       return 1;
     }
   } else if (hr2 == NULL) {
     return -1;
   }
   double gc_eff1 = hr1->gc_efficiency();
   double gc_eff2 = hr2->gc_efficiency();
   if (gc_eff1 > gc_eff2) {
     return -1;
   } if (gc_eff1 < gc_eff2) {
     return 1;
   } else {
     return 0;
   }
 }
 static int order_regions(HeapRegion** hr1p, HeapRegion** hr2p) {
   return order_regions(*hr1p, *hr2p);
 }
 CollectionSetChooser::CollectionSetChooser() :
   // The line below is the worst bit of C++ hackery I've ever written
   // (Detlefs, 11/23).  You should think of it as equivalent to
   // "_regions(100, true)": initialize the growable array and inform it
   // that it should allocate its elem array(s) on the C heap.
   //
   // The first argument, however, is actually a comma expression
   // (set_allocation_type(this, C_HEAP), 100). The purpose of the
   // set_allocation_type() call is to replace the default allocation
   // type for embedded objects STACK_OR_EMBEDDED with C_HEAP. It will
   // allow to pass the assert in GenericGrowableArray() which checks
   // that a growable array object must be on C heap if elements are.
   //
   // Note: containing object is allocated on C heap since it is CHeapObj.
   //
   _regions((ResourceObj::set_allocation_type((address) &_regions,
                                              ResourceObj::C_HEAP),
 ), true /* C_Heap */),
     _curr_index(0), _length(0), _first_par_unreserved_idx(0),
     _region_live_threshold_bytes(0), _remaining_reclaimable_bytes(0) {
   _region_live_threshold_bytes =
     HeapRegion::GrainBytes * (size_t) G1OldCSetRegionLiveThresholdPercent / 100;
 }
 #ifndef PRODUCT
 void CollectionSetChooser::verify() {
   guarantee(_length <= regions_length(),
          err_msg("_length: %u regions length: %u", _length, regions_length()));
   guarantee(_curr_index <= _length,
             err_msg("_curr_index: %u _length: %u", _curr_index, _length));
   uint index = 0;
   size_t sum_of_reclaimable_bytes = 0;
   while (index < _curr_index) {
     guarantee(regions_at(index) == NULL,
               "all entries before _curr_index should be NULL");
     index += 1;
   }
   HeapRegion *prev = NULL;
   while (index < _length) {
     HeapRegion *curr = regions_at(index++);
     guarantee(curr != NULL, "Regions in _regions array cannot be NULL");
     guarantee(!curr->is_young(), "should not be young!");
     guarantee(!curr->isHumongous(), "should not be humongous!");
     if (prev != NULL) {
       guarantee(order_regions(prev, curr) != 1,
                 err_msg("GC eff prev: %1.4f GC eff curr: %1.4f",
                         prev->gc_efficiency(), curr->gc_efficiency()));
     }
     sum_of_reclaimable_bytes += curr->reclaimable_bytes();
     prev = curr;
   }
   guarantee(sum_of_reclaimable_bytes == _remaining_reclaimable_bytes,
             err_msg("reclaimable bytes inconsistent, "
                     "remaining: "SIZE_FORMAT" sum: "SIZE_FORMAT,
                     _remaining_reclaimable_bytes, sum_of_reclaimable_bytes));
 }
 #endif // !PRODUCT
 void CollectionSetChooser::sort_regions() {
   // First trim any unused portion of the top in the parallel case.
   if (_first_par_unreserved_idx > 0) {
     assert(_first_par_unreserved_idx <= regions_length(),
            "Or we didn't reserved enough length");
     regions_trunc_to(_first_par_unreserved_idx);
   }
   _regions.sort(order_regions);
   assert(_length <= regions_length(), "Requirement");
 #ifdef ASSERT
   for (uint i = 0; i < _length; i++) {
     assert(regions_at(i) != NULL, "Should be true by sorting!");
   }
 #endif // ASSERT
   if (G1PrintRegionLivenessInfo) {
     G1PrintRegionLivenessInfoClosure cl(gclog_or_tty, "Post-Sorting");
     for (uint i = 0; i < _length; ++i) {
       HeapRegion* r = regions_at(i);
       cl.doHeapRegion(r);
     }
   }
   verify();
 }
 uint CollectionSetChooser::calc_min_old_cset_length() {
   // The min old CSet region bound is based on the maximum desired
   // number of mixed GCs after a cycle. I.e., even if some old regions
   // look expensive, we should add them to the CSet anyway to make
   // sure we go through the available old regions in no more than the
   // maximum desired number of mixed GCs.
   //
   // The calculation is based on the number of marked regions we added
   // to the CSet chooser in the first place, not how many remain, so
   // that the result is the same during all mixed GCs that follow a cycle.
   const size_t region_num = (size_t) _length;
   const size_t gc_num = (size_t) G1MixedGCCountTarget;
   size_t result = region_num / gc_num;
   // emulate ceiling
   if (result * gc_num < region_num) {
     result += 1;
   }
   return (uint) result;
 }
 uint CollectionSetChooser::calc_max_old_cset_length() {
   // The max old CSet region bound is based on the threshold expressed
   // as a percentage of the heap size. I.e., it should bound the
   // number of old regions added to the CSet irrespective of how many
   // of them are available.
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   const size_t region_num = g1h->n_regions();
   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
   size_t result = region_num * perc / 100;
   // emulate ceiling
   if (100 * result < region_num * perc) {
     result += 1;
   }
   return (uint) result;
 }
 void CollectionSetChooser::add_region(HeapRegion* hr) {
   assert(!hr->isHumongous(),
          "Humongous regions shouldn't be added to the collection set");
   assert(!hr->is_young(), "should not be young!");
   _regions.append(hr);
   _length++;
   _remaining_reclaimable_bytes += hr->reclaimable_bytes();
   hr->calc_gc_efficiency();
 }
 void CollectionSetChooser::prepare_for_par_region_addition(uint n_regions,
                                                            uint chunk_size) {
   _first_par_unreserved_idx = 0;
   uint n_threads = (uint) ParallelGCThreads;
   if (UseDynamicNumberOfGCThreads) {
     assert(G1CollectedHeap::heap()->workers()->active_workers() > 0,
       "Should have been set earlier");
     // This is defensive code. As the assertion above says, the number
     // of active threads should be > 0, but in case there is some path
     // or some improperly initialized variable with leads to no
     // active threads, protect against that in a product build.
     n_threads = MAX2(G1CollectedHeap::heap()->workers()->active_workers(),
 U);
   }
   uint max_waste = n_threads * chunk_size;
   // it should be aligned with respect to chunk_size
   uint aligned_n_regions = (n_regions + chunk_size - 1) / chunk_size * chunk_size;
   assert(aligned_n_regions % chunk_size == 0, "should be aligned");
   regions_at_put_grow(aligned_n_regions + max_waste - 1, NULL);
 }
 uint CollectionSetChooser::claim_array_chunk(uint chunk_size) {
   uint res = (uint) Atomic::add((jint) chunk_size,
                                 (volatile jint*) &_first_par_unreserved_idx);
   assert(regions_length() > res + chunk_size - 1,
          "Should already have been expanded");
   return res - chunk_size;
 }
 void CollectionSetChooser::set_region(uint index, HeapRegion* hr) {
   assert(regions_at(index) == NULL, "precondition");
   assert(!hr->is_young(), "should not be young!");
   regions_at_put(index, hr);
   hr->calc_gc_efficiency();
 }
 void CollectionSetChooser::update_totals(uint region_num,
                                          size_t reclaimable_bytes) {
   // Only take the lock if we actually need to update the totals.
   if (region_num > 0) {
     assert(reclaimable_bytes > 0, "invariant");
     // We could have just used atomics instead of taking the
     // lock. However, we currently don't have an atomic add for size_t.
     MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
     _length += region_num;
     _remaining_reclaimable_bytes += reclaimable_bytes;
   } else {
     assert(reclaimable_bytes == 0, "invariant");
   }
 }
 void CollectionSetChooser::clear() {
   _regions.clear();
   _curr_index = 0;
   _length = 0;
   _remaining_reclaimable_bytes = 0;
 };

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/collectionSetChooser.cpp@5baec2e69518 (annotated)

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