ysr@777: /*
stefank@2314:  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
ysr@777:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
ysr@777:  *
ysr@777:  * This code is free software; you can redistribute it and/or modify it
ysr@777:  * under the terms of the GNU General Public License version 2 only, as
ysr@777:  * published by the Free Software Foundation.
ysr@777:  *
ysr@777:  * This code is distributed in the hope that it will be useful, but WITHOUT
ysr@777:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
ysr@777:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
ysr@777:  * version 2 for more details (a copy is included in the LICENSE file that
ysr@777:  * accompanied this code).
ysr@777:  *
ysr@777:  * You should have received a copy of the GNU General Public License version
ysr@777:  * 2 along with this work; if not, write to the Free Software Foundation,
ysr@777:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
ysr@777:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
ysr@777:  *
ysr@777:  */
ysr@777: 
stefank@2314: #include "precompiled.hpp"
stefank@2314: #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
stefank@2314: #include "gc_implementation/g1/heapRegionSeq.hpp"
stefank@2314: #include "memory/allocation.hpp"
ysr@777: 
ysr@777: // Local to this file.
ysr@777: 
ysr@777: static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {
ysr@777:   if ((*hr1p)->end() <= (*hr2p)->bottom()) return -1;
ysr@777:   else if ((*hr2p)->end() <= (*hr1p)->bottom()) return 1;
ysr@777:   else if (*hr1p == *hr2p) return 0;
ysr@777:   else {
ysr@777:     assert(false, "We should never compare distinct overlapping regions.");
ysr@777:   }
ysr@777:   return 0;
ysr@777: }
ysr@777: 
iveresov@828: HeapRegionSeq::HeapRegionSeq(const size_t max_size) :
ysr@777:   _alloc_search_start(0),
ysr@777:   // The line below is the worst bit of C++ hackery I've ever written
ysr@777:   // (Detlefs, 11/23).  You should think of it as equivalent to
ysr@777:   // "_regions(100, true)": initialize the growable array and inform it
kvn@2043:   // that it should allocate its elem array(s) on the C heap.
kvn@2043:   //
kvn@2043:   // The first argument, however, is actually a comma expression
kvn@2043:   // (set_allocation_type(this, C_HEAP), 100). The purpose of the
kvn@2043:   // set_allocation_type() call is to replace the default allocation
kvn@2043:   // type for embedded objects STACK_OR_EMBEDDED with C_HEAP. It will
kvn@2043:   // allow to pass the assert in GenericGrowableArray() which checks
kvn@2043:   // that a growable array object must be on C heap if elements are.
kvn@2043:   //
kvn@2043:   // Note: containing object is allocated on C heap since it is CHeapObj.
kvn@2043:   //
kvn@2043:   _regions((ResourceObj::set_allocation_type((address)&_regions,
kvn@2043:                                              ResourceObj::C_HEAP),
iveresov@828:             (int)max_size),
ysr@777:            true),
ysr@777:   _next_rr_candidate(0),
ysr@777:   _seq_bottom(NULL)
ysr@777: {}
ysr@777: 
ysr@777: // Private methods.
ysr@777: 
ysr@777: HeapWord*
ysr@777: HeapRegionSeq::alloc_obj_from_region_index(int ind, size_t word_size) {
ysr@777:   assert(G1CollectedHeap::isHumongous(word_size),
ysr@777:          "Allocation size should be humongous");
ysr@777:   int cur = ind;
ysr@777:   int first = cur;
ysr@777:   size_t sumSizes = 0;
ysr@777:   while (cur < _regions.length() && sumSizes < word_size) {
ysr@777:     // Loop invariant:
ysr@777:     //  For all i in [first, cur):
ysr@777:     //       _regions.at(i)->is_empty()
ysr@777:     //    && _regions.at(i) is contiguous with its predecessor, if any
ysr@777:     //  && sumSizes is the sum of the sizes of the regions in the interval
ysr@777:     //       [first, cur)
ysr@777:     HeapRegion* curhr = _regions.at(cur);
ysr@777:     if (curhr->is_empty()
ysr@777:         && (first == cur
ysr@777:             || (_regions.at(cur-1)->end() ==
ysr@777:                 curhr->bottom()))) {
ysr@777:       sumSizes += curhr->capacity() / HeapWordSize;
ysr@777:     } else {
ysr@777:       first = cur + 1;
ysr@777:       sumSizes = 0;
ysr@777:     }
ysr@777:     cur++;
ysr@777:   }
ysr@777:   if (sumSizes >= word_size) {
ysr@777:     _alloc_search_start = cur;
tonyp@2241: 
tonyp@2241:     // We need to initialize the region(s) we just discovered. This is
tonyp@2241:     // a bit tricky given that it can happen concurrently with
tonyp@2241:     // refinement threads refining cards on these regions and
tonyp@2241:     // potentially wanting to refine the BOT as they are scanning
tonyp@2241:     // those cards (this can happen shortly after a cleanup; see CR
tonyp@2241:     // 6991377). So we have to set up the region(s) carefully and in
tonyp@2241:     // a specific order.
tonyp@2241: 
tonyp@2241:     // Currently, allocs_are_zero_filled() returns false. The zero
tonyp@2241:     // filling infrastructure will be going away soon (see CR 6977804).
tonyp@2241:     // So no need to do anything else here.
ysr@777:     bool zf = G1CollectedHeap::heap()->allocs_are_zero_filled();
tonyp@2241:     assert(!zf, "not supported");
tonyp@2241: 
tonyp@2241:     // This will be the "starts humongous" region.
ysr@777:     HeapRegion* first_hr = _regions.at(first);
tonyp@2241:     {
tonyp@2241:       MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
tonyp@2241:       first_hr->set_zero_fill_allocated();
tonyp@2241:     }
tonyp@2241:     // The header of the new object will be placed at the bottom of
tonyp@2241:     // the first region.
tonyp@2241:     HeapWord* new_obj = first_hr->bottom();
tonyp@2241:     // This will be the new end of the first region in the series that
tonyp@2241:     // should also match the end of the last region in the seriers.
tonyp@2241:     // (Note: sumSizes = "region size" x "number of regions we found").
tonyp@2241:     HeapWord* new_end = new_obj + sumSizes;
tonyp@2241:     // This will be the new top of the first region that will reflect
tonyp@2241:     // this allocation.
tonyp@2241:     HeapWord* new_top = new_obj + word_size;
tonyp@2241: 
tonyp@2241:     // First, we need to zero the header of the space that we will be
tonyp@2241:     // allocating. When we update top further down, some refinement
tonyp@2241:     // threads might try to scan the region. By zeroing the header we
tonyp@2241:     // ensure that any thread that will try to scan the region will
tonyp@2241:     // come across the zero klass word and bail out.
tonyp@2241:     //
tonyp@2241:     // NOTE: It would not have been correct to have used
tonyp@2241:     // CollectedHeap::fill_with_object() and make the space look like
tonyp@2241:     // an int array. The thread that is doing the allocation will
tonyp@2241:     // later update the object header to a potentially different array
tonyp@2241:     // type and, for a very short period of time, the klass and length
tonyp@2241:     // fields will be inconsistent. This could cause a refinement
tonyp@2241:     // thread to calculate the object size incorrectly.
tonyp@2241:     Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
tonyp@2241: 
tonyp@2241:     // We will set up the first region as "starts humongous". This
tonyp@2241:     // will also update the BOT covering all the regions to reflect
tonyp@2241:     // that there is a single object that starts at the bottom of the
tonyp@2241:     // first region.
tonyp@2241:     first_hr->set_startsHumongous(new_end);
tonyp@2241: 
tonyp@2241:     // Then, if there are any, we will set up the "continues
tonyp@2241:     // humongous" regions.
tonyp@2241:     HeapRegion* hr = NULL;
tonyp@2241:     for (int i = first + 1; i < cur; ++i) {
tonyp@2241:       hr = _regions.at(i);
ysr@777:       {
ysr@777:         MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
ysr@777:         hr->set_zero_fill_allocated();
ysr@777:       }
tonyp@2241:       hr->set_continuesHumongous(first_hr);
tonyp@2241:     }
tonyp@2241:     // If we have "continues humongous" regions (hr != NULL), then the
tonyp@2241:     // end of the last one should match new_end.
tonyp@2241:     assert(hr == NULL || hr->end() == new_end, "sanity");
tonyp@2241: 
tonyp@2241:     // Up to this point no concurrent thread would have been able to
tonyp@2241:     // do any scanning on any region in this series. All the top
tonyp@2241:     // fields still point to bottom, so the intersection between
tonyp@2241:     // [bottom,top] and [card_start,card_end] will be empty. Before we
tonyp@2241:     // update the top fields, we'll do a storestore to make sure that
tonyp@2241:     // no thread sees the update to top before the zeroing of the
tonyp@2241:     // object header and the BOT initialization.
tonyp@2241:     OrderAccess::storestore();
tonyp@2241: 
tonyp@2241:     // Now that the BOT and the object header have been initialized,
tonyp@2241:     // we can update top of the "starts humongous" region.
tonyp@2241:     assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
tonyp@2241:            "new_top should be in this region");
tonyp@2241:     first_hr->set_top(new_top);
tonyp@2241: 
tonyp@2241:     // Now, we will update the top fields of the "continues humongous"
tonyp@2241:     // regions. The reason we need to do this is that, otherwise,
tonyp@2241:     // these regions would look empty and this will confuse parts of
tonyp@2241:     // G1. For example, the code that looks for a consecutive number
tonyp@2241:     // of empty regions will consider them empty and try to
tonyp@2241:     // re-allocate them. We can extend is_empty() to also include
tonyp@2241:     // !continuesHumongous(), but it is easier to just update the top
tonyp@2241:     // fields here.
tonyp@2241:     hr = NULL;
tonyp@2241:     for (int i = first + 1; i < cur; ++i) {
tonyp@2241:       hr = _regions.at(i);
tonyp@2241:       if ((i + 1) == cur) {
tonyp@2241:         // last continues humongous region
tonyp@2241:         assert(hr->bottom() < new_top && new_top <= hr->end(),
tonyp@2241:                "new_top should fall on this region");
tonyp@2241:         hr->set_top(new_top);
ysr@777:       } else {
tonyp@2241:         // not last one
tonyp@2241:         assert(new_top > hr->end(), "new_top should be above this region");
tonyp@2241:         hr->set_top(hr->end());
ysr@777:       }
ysr@777:     }
tonyp@2241:     // If we have continues humongous regions (hr != NULL), then the
tonyp@2241:     // end of the last one should match new_end and its top should
tonyp@2241:     // match new_top.
tonyp@2241:     assert(hr == NULL ||
tonyp@2241:            (hr->end() == new_end && hr->top() == new_top), "sanity");
tonyp@2241: 
tonyp@2241:     return new_obj;
ysr@777:   } else {
ysr@777:     // If we started from the beginning, we want to know why we can't alloc.
ysr@777:     return NULL;
ysr@777:   }
ysr@777: }
ysr@777: 
apetrusenko@1112: void HeapRegionSeq::print_empty_runs() {
ysr@777:   int empty_run = 0;
ysr@777:   int n_empty = 0;
ysr@777:   int empty_run_start;
ysr@777:   for (int i = 0; i < _regions.length(); i++) {
ysr@777:     HeapRegion* r = _regions.at(i);
ysr@777:     if (r->continuesHumongous()) continue;
apetrusenko@1112:     if (r->is_empty()) {
ysr@777:       assert(!r->isHumongous(), "H regions should not be empty.");
ysr@777:       if (empty_run == 0) empty_run_start = i;
ysr@777:       empty_run++;
ysr@777:       n_empty++;
ysr@777:     } else {
ysr@777:       if (empty_run > 0) {
ysr@777:         gclog_or_tty->print("  %d:%d", empty_run_start, empty_run);
ysr@777:         empty_run = 0;
ysr@777:       }
ysr@777:     }
ysr@777:   }
ysr@777:   if (empty_run > 0) {
ysr@777:     gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);
ysr@777:   }
ysr@777:   gclog_or_tty->print_cr(" [tot = %d]", n_empty);
ysr@777: }
ysr@777: 
ysr@777: int HeapRegionSeq::find(HeapRegion* hr) {
ysr@777:   // FIXME: optimized for adjacent regions of fixed size.
ysr@777:   int ind = hr->hrs_index();
ysr@777:   if (ind != -1) {
ysr@777:     assert(_regions.at(ind) == hr, "Mismatch");
ysr@777:   }
ysr@777:   return ind;
ysr@777: }
ysr@777: 
ysr@777: 
ysr@777: // Public methods.
ysr@777: 
ysr@777: void HeapRegionSeq::insert(HeapRegion* hr) {
iveresov@828:   assert(!_regions.is_full(), "Too many elements in HeapRegionSeq");
ysr@777:   if (_regions.length() == 0
ysr@777:       || _regions.top()->end() <= hr->bottom()) {
ysr@777:     hr->set_hrs_index(_regions.length());
ysr@777:     _regions.append(hr);
ysr@777:   } else {
ysr@777:     _regions.append(hr);
ysr@777:     _regions.sort(orderRegions);
ysr@777:     for (int i = 0; i < _regions.length(); i++) {
ysr@777:       _regions.at(i)->set_hrs_index(i);
ysr@777:     }
ysr@777:   }
ysr@777:   char* bot = (char*)_regions.at(0)->bottom();
ysr@777:   if (_seq_bottom == NULL || bot < _seq_bottom) _seq_bottom = bot;
ysr@777: }
ysr@777: 
ysr@777: size_t HeapRegionSeq::length() {
ysr@777:   return _regions.length();
ysr@777: }
ysr@777: 
ysr@777: size_t HeapRegionSeq::free_suffix() {
ysr@777:   size_t res = 0;
ysr@777:   int first = _regions.length() - 1;
ysr@777:   int cur = first;
ysr@777:   while (cur >= 0 &&
ysr@777:          (_regions.at(cur)->is_empty()
ysr@777:           && (first == cur
ysr@777:               || (_regions.at(cur+1)->bottom() ==
ysr@777:                   _regions.at(cur)->end())))) {
ysr@777:       res++;
ysr@777:       cur--;
ysr@777:   }
ysr@777:   return res;
ysr@777: }
ysr@777: 
ysr@777: HeapWord* HeapRegionSeq::obj_allocate(size_t word_size) {
ysr@777:   int cur = _alloc_search_start;
ysr@777:   // Make sure "cur" is a valid index.
ysr@777:   assert(cur >= 0, "Invariant.");
ysr@777:   HeapWord* res = alloc_obj_from_region_index(cur, word_size);
ysr@777:   if (res == NULL)
ysr@777:     res = alloc_obj_from_region_index(0, word_size);
ysr@777:   return res;
ysr@777: }
ysr@777: 
ysr@777: void HeapRegionSeq::iterate(HeapRegionClosure* blk) {
ysr@777:   iterate_from((HeapRegion*)NULL, blk);
ysr@777: }
ysr@777: 
ysr@777: // The first argument r is the heap region at which iteration begins.
ysr@777: // This operation runs fastest when r is NULL, or the heap region for
ysr@777: // which a HeapRegionClosure most recently returned true, or the
ysr@777: // heap region immediately to its right in the sequence.  In all
ysr@777: // other cases a linear search is required to find the index of r.
ysr@777: 
ysr@777: void HeapRegionSeq::iterate_from(HeapRegion* r, HeapRegionClosure* blk) {
ysr@777: 
ysr@777:   // :::: FIXME ::::
ysr@777:   // Static cache value is bad, especially when we start doing parallel
ysr@777:   // remembered set update. For now just don't cache anything (the
ysr@777:   // code in the def'd out blocks).
ysr@777: 
ysr@777: #if 0
ysr@777:   static int cached_j = 0;
ysr@777: #endif
ysr@777:   int len = _regions.length();
ysr@777:   int j = 0;
ysr@777:   // Find the index of r.
ysr@777:   if (r != NULL) {
ysr@777: #if 0
ysr@777:     assert(cached_j >= 0, "Invariant.");
ysr@777:     if ((cached_j < len) && (r == _regions.at(cached_j))) {
ysr@777:       j = cached_j;
ysr@777:     } else if ((cached_j + 1 < len) && (r == _regions.at(cached_j + 1))) {
ysr@777:       j = cached_j + 1;
ysr@777:     } else {
ysr@777:       j = find(r);
ysr@777: #endif
ysr@777:       if (j < 0) {
ysr@777:         j = 0;
ysr@777:       }
ysr@777: #if 0
ysr@777:     }
ysr@777: #endif
ysr@777:   }
ysr@777:   int i;
ysr@777:   for (i = j; i < len; i += 1) {
ysr@777:     int res = blk->doHeapRegion(_regions.at(i));
ysr@777:     if (res) {
ysr@777: #if 0
ysr@777:       cached_j = i;
ysr@777: #endif
ysr@777:       blk->incomplete();
ysr@777:       return;
ysr@777:     }
ysr@777:   }
ysr@777:   for (i = 0; i < j; i += 1) {
ysr@777:     int res = blk->doHeapRegion(_regions.at(i));
ysr@777:     if (res) {
ysr@777: #if 0
ysr@777:       cached_j = i;
ysr@777: #endif
ysr@777:       blk->incomplete();
ysr@777:       return;
ysr@777:     }
ysr@777:   }
ysr@777: }
ysr@777: 
ysr@777: void HeapRegionSeq::iterate_from(int idx, HeapRegionClosure* blk) {
ysr@777:   int len = _regions.length();
ysr@777:   int i;
ysr@777:   for (i = idx; i < len; i++) {
ysr@777:     if (blk->doHeapRegion(_regions.at(i))) {
ysr@777:       blk->incomplete();
ysr@777:       return;
ysr@777:     }
ysr@777:   }
ysr@777:   for (i = 0; i < idx; i++) {
ysr@777:     if (blk->doHeapRegion(_regions.at(i))) {
ysr@777:       blk->incomplete();
ysr@777:       return;
ysr@777:     }
ysr@777:   }
ysr@777: }
ysr@777: 
ysr@777: MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes,
ysr@777:                                    size_t& num_regions_deleted) {
ysr@777:   assert(shrink_bytes % os::vm_page_size() == 0, "unaligned");
ysr@777:   assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned");
ysr@777: 
ysr@777:   if (_regions.length() == 0) {
ysr@777:     num_regions_deleted = 0;
ysr@777:     return MemRegion();
ysr@777:   }
ysr@777:   int j = _regions.length() - 1;
ysr@777:   HeapWord* end = _regions.at(j)->end();
ysr@777:   HeapWord* last_start = end;
ysr@777:   while (j >= 0 && shrink_bytes > 0) {
ysr@777:     HeapRegion* cur = _regions.at(j);
ysr@777:     // We have to leave humongous regions where they are,
ysr@777:     // and work around them.
ysr@777:     if (cur->isHumongous()) {
ysr@777:       return MemRegion(last_start, end);
ysr@777:     }
ysr@777:     assert(cur == _regions.top(), "Should be top");
ysr@777:     if (!cur->is_empty()) break;
ysr@1395:     cur->reset_zero_fill();
ysr@777:     shrink_bytes -= cur->capacity();
ysr@777:     num_regions_deleted++;
ysr@777:     _regions.pop();
ysr@777:     last_start = cur->bottom();
ysr@777:     // We need to delete these somehow, but can't currently do so here: if
ysr@777:     // we do, the ZF thread may still access the deleted region.  We'll
ysr@777:     // leave this here as a reminder that we have to do something about
ysr@777:     // this.
ysr@777:     // delete cur;
ysr@777:     j--;
ysr@777:   }
ysr@777:   return MemRegion(last_start, end);
ysr@777: }
ysr@777: 
ysr@777: 
ysr@777: class PrintHeapRegionClosure : public  HeapRegionClosure {
ysr@777: public:
ysr@777:   bool doHeapRegion(HeapRegion* r) {
ysr@777:     gclog_or_tty->print(PTR_FORMAT ":", r);
ysr@777:     r->print();
ysr@777:     return false;
ysr@777:   }
ysr@777: };
ysr@777: 
ysr@777: void HeapRegionSeq::print() {
ysr@777:   PrintHeapRegionClosure cl;
ysr@777:   iterate(&cl);
ysr@777: }