aoqi@0: /*
aoqi@0:  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #include "precompiled.hpp"
aoqi@0: #include "gc_implementation/g1/collectionSetChooser.hpp"
aoqi@0: #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
aoqi@0: #include "gc_implementation/g1/g1CollectorPolicy.hpp"
aoqi@0: #include "gc_implementation/g1/g1ErgoVerbose.hpp"
aoqi@0: #include "memory/space.inline.hpp"
aoqi@0: 
aoqi@0: // Even though we don't use the GC efficiency in our heuristics as
aoqi@0: // much as we used to, we still order according to GC efficiency. This
aoqi@0: // will cause regions with a lot of live objects and large RSets to
aoqi@0: // end up at the end of the array. Given that we might skip collecting
aoqi@0: // the last few old regions, if after a few mixed GCs the remaining
aoqi@0: // have reclaimable bytes under a certain threshold, the hope is that
aoqi@0: // the ones we'll skip are ones with both large RSets and a lot of
aoqi@0: // live objects, not the ones with just a lot of live objects if we
aoqi@0: // ordered according to the amount of reclaimable bytes per region.
aoqi@0: static int order_regions(HeapRegion* hr1, HeapRegion* hr2) {
aoqi@0:   if (hr1 == NULL) {
aoqi@0:     if (hr2 == NULL) {
aoqi@0:       return 0;
aoqi@0:     } else {
aoqi@0:       return 1;
aoqi@0:     }
aoqi@0:   } else if (hr2 == NULL) {
aoqi@0:     return -1;
aoqi@0:   }
aoqi@0: 
aoqi@0:   double gc_eff1 = hr1->gc_efficiency();
aoqi@0:   double gc_eff2 = hr2->gc_efficiency();
aoqi@0:   if (gc_eff1 > gc_eff2) {
aoqi@0:     return -1;
aoqi@0:   } if (gc_eff1 < gc_eff2) {
aoqi@0:     return 1;
aoqi@0:   } else {
aoqi@0:     return 0;
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: static int order_regions(HeapRegion** hr1p, HeapRegion** hr2p) {
aoqi@0:   return order_regions(*hr1p, *hr2p);
aoqi@0: }
aoqi@0: 
aoqi@0: CollectionSetChooser::CollectionSetChooser() :
aoqi@0:   // The line below is the worst bit of C++ hackery I've ever written
aoqi@0:   // (Detlefs, 11/23).  You should think of it as equivalent to
aoqi@0:   // "_regions(100, true)": initialize the growable array and inform it
aoqi@0:   // that it should allocate its elem array(s) on the C heap.
aoqi@0:   //
aoqi@0:   // The first argument, however, is actually a comma expression
aoqi@0:   // (set_allocation_type(this, C_HEAP), 100). The purpose of the
aoqi@0:   // set_allocation_type() call is to replace the default allocation
aoqi@0:   // type for embedded objects STACK_OR_EMBEDDED with C_HEAP. It will
aoqi@0:   // allow to pass the assert in GenericGrowableArray() which checks
aoqi@0:   // that a growable array object must be on C heap if elements are.
aoqi@0:   //
aoqi@0:   // Note: containing object is allocated on C heap since it is CHeapObj.
aoqi@0:   //
aoqi@0:   _regions((ResourceObj::set_allocation_type((address) &_regions,
aoqi@0:                                              ResourceObj::C_HEAP),
aoqi@0:                   100), true /* C_Heap */),
aoqi@0:     _curr_index(0), _length(0), _first_par_unreserved_idx(0),
aoqi@0:     _region_live_threshold_bytes(0), _remaining_reclaimable_bytes(0) {
aoqi@0:   _region_live_threshold_bytes =
aoqi@0:     HeapRegion::GrainBytes * (size_t) G1MixedGCLiveThresholdPercent / 100;
aoqi@0: }
aoqi@0: 
aoqi@0: #ifndef PRODUCT
aoqi@0: void CollectionSetChooser::verify() {
aoqi@0:   guarantee(_length <= regions_length(),
aoqi@0:          err_msg("_length: %u regions length: %u", _length, regions_length()));
aoqi@0:   guarantee(_curr_index <= _length,
aoqi@0:             err_msg("_curr_index: %u _length: %u", _curr_index, _length));
aoqi@0:   uint index = 0;
aoqi@0:   size_t sum_of_reclaimable_bytes = 0;
aoqi@0:   while (index < _curr_index) {
aoqi@0:     guarantee(regions_at(index) == NULL,
aoqi@0:               "all entries before _curr_index should be NULL");
aoqi@0:     index += 1;
aoqi@0:   }
aoqi@0:   HeapRegion *prev = NULL;
aoqi@0:   while (index < _length) {
aoqi@0:     HeapRegion *curr = regions_at(index++);
aoqi@0:     guarantee(curr != NULL, "Regions in _regions array cannot be NULL");
aoqi@0:     guarantee(!curr->is_young(), "should not be young!");
aoqi@0:     guarantee(!curr->isHumongous(), "should not be humongous!");
aoqi@0:     if (prev != NULL) {
aoqi@0:       guarantee(order_regions(prev, curr) != 1,
aoqi@0:                 err_msg("GC eff prev: %1.4f GC eff curr: %1.4f",
aoqi@0:                         prev->gc_efficiency(), curr->gc_efficiency()));
aoqi@0:     }
aoqi@0:     sum_of_reclaimable_bytes += curr->reclaimable_bytes();
aoqi@0:     prev = curr;
aoqi@0:   }
aoqi@0:   guarantee(sum_of_reclaimable_bytes == _remaining_reclaimable_bytes,
aoqi@0:             err_msg("reclaimable bytes inconsistent, "
kevinw@9327:                     "remaining: " SIZE_FORMAT " sum: " SIZE_FORMAT,
aoqi@0:                     _remaining_reclaimable_bytes, sum_of_reclaimable_bytes));
aoqi@0: }
aoqi@0: #endif // !PRODUCT
aoqi@0: 
aoqi@0: void CollectionSetChooser::sort_regions() {
aoqi@0:   // First trim any unused portion of the top in the parallel case.
aoqi@0:   if (_first_par_unreserved_idx > 0) {
aoqi@0:     assert(_first_par_unreserved_idx <= regions_length(),
aoqi@0:            "Or we didn't reserved enough length");
aoqi@0:     regions_trunc_to(_first_par_unreserved_idx);
aoqi@0:   }
aoqi@0:   _regions.sort(order_regions);
aoqi@0:   assert(_length <= regions_length(), "Requirement");
aoqi@0: #ifdef ASSERT
aoqi@0:   for (uint i = 0; i < _length; i++) {
aoqi@0:     assert(regions_at(i) != NULL, "Should be true by sorting!");
aoqi@0:   }
aoqi@0: #endif // ASSERT
aoqi@0:   if (G1PrintRegionLivenessInfo) {
aoqi@0:     G1PrintRegionLivenessInfoClosure cl(gclog_or_tty, "Post-Sorting");
aoqi@0:     for (uint i = 0; i < _length; ++i) {
aoqi@0:       HeapRegion* r = regions_at(i);
aoqi@0:       cl.doHeapRegion(r);
aoqi@0:     }
aoqi@0:   }
aoqi@0:   verify();
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: void CollectionSetChooser::add_region(HeapRegion* hr) {
aoqi@0:   assert(!hr->isHumongous(),
aoqi@0:          "Humongous regions shouldn't be added to the collection set");
aoqi@0:   assert(!hr->is_young(), "should not be young!");
aoqi@0:   _regions.append(hr);
aoqi@0:   _length++;
aoqi@0:   _remaining_reclaimable_bytes += hr->reclaimable_bytes();
aoqi@0:   hr->calc_gc_efficiency();
aoqi@0: }
aoqi@0: 
aoqi@0: void CollectionSetChooser::prepare_for_par_region_addition(uint n_regions,
aoqi@0:                                                            uint chunk_size) {
aoqi@0:   _first_par_unreserved_idx = 0;
aoqi@0:   uint n_threads = (uint) ParallelGCThreads;
aoqi@0:   if (UseDynamicNumberOfGCThreads) {
aoqi@0:     assert(G1CollectedHeap::heap()->workers()->active_workers() > 0,
aoqi@0:       "Should have been set earlier");
aoqi@0:     // This is defensive code. As the assertion above says, the number
aoqi@0:     // of active threads should be > 0, but in case there is some path
aoqi@0:     // or some improperly initialized variable with leads to no
aoqi@0:     // active threads, protect against that in a product build.
aoqi@0:     n_threads = MAX2(G1CollectedHeap::heap()->workers()->active_workers(),
aoqi@0:                      1U);
aoqi@0:   }
aoqi@0:   uint max_waste = n_threads * chunk_size;
aoqi@0:   // it should be aligned with respect to chunk_size
aoqi@0:   uint aligned_n_regions = (n_regions + chunk_size - 1) / chunk_size * chunk_size;
aoqi@0:   assert(aligned_n_regions % chunk_size == 0, "should be aligned");
aoqi@0:   regions_at_put_grow(aligned_n_regions + max_waste - 1, NULL);
aoqi@0: }
aoqi@0: 
aoqi@0: uint CollectionSetChooser::claim_array_chunk(uint chunk_size) {
aoqi@0:   uint res = (uint) Atomic::add((jint) chunk_size,
aoqi@0:                                 (volatile jint*) &_first_par_unreserved_idx);
aoqi@0:   assert(regions_length() > res + chunk_size - 1,
aoqi@0:          "Should already have been expanded");
aoqi@0:   return res - chunk_size;
aoqi@0: }
aoqi@0: 
aoqi@0: void CollectionSetChooser::set_region(uint index, HeapRegion* hr) {
aoqi@0:   assert(regions_at(index) == NULL, "precondition");
aoqi@0:   assert(!hr->is_young(), "should not be young!");
aoqi@0:   regions_at_put(index, hr);
aoqi@0:   hr->calc_gc_efficiency();
aoqi@0: }
aoqi@0: 
aoqi@0: void CollectionSetChooser::update_totals(uint region_num,
aoqi@0:                                          size_t reclaimable_bytes) {
aoqi@0:   // Only take the lock if we actually need to update the totals.
aoqi@0:   if (region_num > 0) {
aoqi@0:     assert(reclaimable_bytes > 0, "invariant");
aoqi@0:     // We could have just used atomics instead of taking the
aoqi@0:     // lock. However, we currently don't have an atomic add for size_t.
aoqi@0:     MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
aoqi@0:     _length += region_num;
aoqi@0:     _remaining_reclaimable_bytes += reclaimable_bytes;
aoqi@0:   } else {
aoqi@0:     assert(reclaimable_bytes == 0, "invariant");
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void CollectionSetChooser::clear() {
aoqi@0:   _regions.clear();
aoqi@0:   _curr_index = 0;
aoqi@0:   _length = 0;
aoqi@0:   _remaining_reclaimable_bytes = 0;
aoqi@0: };