tonyp@2715: /*
tonyp@3713:  * Copyright (c) 2011, 2012, Oracle and/or its affiliates. All rights reserved.
tonyp@2715:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
tonyp@2715:  *
tonyp@2715:  * This code is free software; you can redistribute it and/or modify it
tonyp@2715:  * under the terms of the GNU General Public License version 2 only, as
tonyp@2715:  * published by the Free Software Foundation.
tonyp@2715:  *
tonyp@2715:  * This code is distributed in the hope that it will be useful, but WITHOUT
tonyp@2715:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
tonyp@2715:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
tonyp@2715:  * version 2 for more details (a copy is included in the LICENSE file that
tonyp@2715:  * accompanied this code).
tonyp@2715:  *
tonyp@2715:  * You should have received a copy of the GNU General Public License version
tonyp@2715:  * 2 along with this work; if not, write to the Free Software Foundation,
tonyp@2715:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
tonyp@2715:  *
tonyp@2715:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
tonyp@2715:  * or visit www.oracle.com if you need additional information or have any
tonyp@2715:  * questions.
tonyp@2715:  *
tonyp@2715:  */
tonyp@2715: 
tonyp@2715: #include "precompiled.hpp"
tonyp@2715: #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
tonyp@2715: #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
tonyp@2715: 
tonyp@2715: G1CollectedHeap* G1AllocRegion::_g1h = NULL;
tonyp@2715: HeapRegion* G1AllocRegion::_dummy_region = NULL;
tonyp@2715: 
tonyp@2715: void G1AllocRegion::setup(G1CollectedHeap* g1h, HeapRegion* dummy_region) {
tonyp@2715:   assert(_dummy_region == NULL, "should be set once");
tonyp@2715:   assert(dummy_region != NULL, "pre-condition");
tonyp@2715:   assert(dummy_region->free() == 0, "pre-condition");
tonyp@2715: 
tonyp@2715:   // Make sure that any allocation attempt on this region will fail
tonyp@2715:   // and will not trigger any asserts.
tonyp@2715:   assert(allocate(dummy_region, 1, false) == NULL, "should fail");
tonyp@2715:   assert(par_allocate(dummy_region, 1, false) == NULL, "should fail");
tonyp@2715:   assert(allocate(dummy_region, 1, true) == NULL, "should fail");
tonyp@2715:   assert(par_allocate(dummy_region, 1, true) == NULL, "should fail");
tonyp@2715: 
tonyp@2715:   _g1h = g1h;
tonyp@2715:   _dummy_region = dummy_region;
tonyp@2715: }
tonyp@2715: 
tonyp@2715: void G1AllocRegion::fill_up_remaining_space(HeapRegion* alloc_region,
tonyp@2715:                                             bool bot_updates) {
tonyp@2715:   assert(alloc_region != NULL && alloc_region != _dummy_region,
tonyp@2715:          "pre-condition");
tonyp@2715: 
tonyp@2715:   // Other threads might still be trying to allocate using a CAS out
tonyp@2715:   // of the region we are trying to retire, as they can do so without
tonyp@2715:   // holding the lock. So, we first have to make sure that noone else
tonyp@2715:   // can allocate out of it by doing a maximal allocation. Even if our
tonyp@2715:   // CAS attempt fails a few times, we'll succeed sooner or later
tonyp@2715:   // given that failed CAS attempts mean that the region is getting
tonyp@2715:   // closed to being full.
tonyp@2715:   size_t free_word_size = alloc_region->free() / HeapWordSize;
tonyp@2715: 
tonyp@2715:   // This is the minimum free chunk we can turn into a dummy
tonyp@2715:   // object. If the free space falls below this, then noone can
tonyp@2715:   // allocate in this region anyway (all allocation requests will be
tonyp@2715:   // of a size larger than this) so we won't have to perform the dummy
tonyp@2715:   // allocation.
tonyp@2715:   size_t min_word_size_to_fill = CollectedHeap::min_fill_size();
tonyp@2715: 
tonyp@2715:   while (free_word_size >= min_word_size_to_fill) {
tonyp@2715:     HeapWord* dummy = par_allocate(alloc_region, free_word_size, bot_updates);
tonyp@2715:     if (dummy != NULL) {
tonyp@2715:       // If the allocation was successful we should fill in the space.
tonyp@2715:       CollectedHeap::fill_with_object(dummy, free_word_size);
tonyp@2715:       alloc_region->set_pre_dummy_top(dummy);
tonyp@2715:       break;
tonyp@2715:     }
tonyp@2715: 
tonyp@2715:     free_word_size = alloc_region->free() / HeapWordSize;
tonyp@2715:     // It's also possible that someone else beats us to the
tonyp@2715:     // allocation and they fill up the region. In that case, we can
tonyp@2715:     // just get out of the loop.
tonyp@2715:   }
tonyp@2715:   assert(alloc_region->free() / HeapWordSize < min_word_size_to_fill,
tonyp@2715:          "post-condition");
tonyp@2715: }
tonyp@2715: 
tonyp@2715: void G1AllocRegion::retire(bool fill_up) {
tonyp@2715:   assert(_alloc_region != NULL, ar_ext_msg(this, "not initialized properly"));
tonyp@2715: 
tonyp@2715:   trace("retiring");
tonyp@2715:   HeapRegion* alloc_region = _alloc_region;
tonyp@2715:   if (alloc_region != _dummy_region) {
tonyp@2715:     // We never have to check whether the active region is empty or not,
tonyp@2715:     // and potentially free it if it is, given that it's guaranteed that
tonyp@2715:     // it will never be empty.
tonyp@2715:     assert(!alloc_region->is_empty(),
tonyp@2715:            ar_ext_msg(this, "the alloc region should never be empty"));
tonyp@2715: 
tonyp@2715:     if (fill_up) {
tonyp@2715:       fill_up_remaining_space(alloc_region, _bot_updates);
tonyp@2715:     }
tonyp@2715: 
tonyp@2715:     assert(alloc_region->used() >= _used_bytes_before,
tonyp@2715:            ar_ext_msg(this, "invariant"));
tonyp@2715:     size_t allocated_bytes = alloc_region->used() - _used_bytes_before;
tonyp@2715:     retire_region(alloc_region, allocated_bytes);
tonyp@2715:     _used_bytes_before = 0;
tonyp@2715:     _alloc_region = _dummy_region;
tonyp@2715:   }
tonyp@2715:   trace("retired");
tonyp@2715: }
tonyp@2715: 
tonyp@2715: HeapWord* G1AllocRegion::new_alloc_region_and_allocate(size_t word_size,
tonyp@2715:                                                        bool force) {
tonyp@2715:   assert(_alloc_region == _dummy_region, ar_ext_msg(this, "pre-condition"));
tonyp@2715:   assert(_used_bytes_before == 0, ar_ext_msg(this, "pre-condition"));
tonyp@2715: 
tonyp@2715:   trace("attempting region allocation");
tonyp@2715:   HeapRegion* new_alloc_region = allocate_new_region(word_size, force);
tonyp@2715:   if (new_alloc_region != NULL) {
tonyp@2715:     new_alloc_region->reset_pre_dummy_top();
tonyp@2715:     // Need to do this before the allocation
tonyp@2715:     _used_bytes_before = new_alloc_region->used();
tonyp@2715:     HeapWord* result = allocate(new_alloc_region, word_size, _bot_updates);
tonyp@2715:     assert(result != NULL, ar_ext_msg(this, "the allocation should succeeded"));
tonyp@2715: 
tonyp@2715:     OrderAccess::storestore();
tonyp@2715:     // Note that we first perform the allocation and then we store the
tonyp@2715:     // region in _alloc_region. This is the reason why an active region
tonyp@2715:     // can never be empty.
tonyp@2715:     _alloc_region = new_alloc_region;
tonyp@3028:     _count += 1;
tonyp@2715:     trace("region allocation successful");
tonyp@2715:     return result;
tonyp@2715:   } else {
tonyp@2715:     trace("region allocation failed");
tonyp@2715:     return NULL;
tonyp@2715:   }
tonyp@2715:   ShouldNotReachHere();
tonyp@2715: }
tonyp@2715: 
tonyp@2715: void G1AllocRegion::fill_in_ext_msg(ar_ext_msg* msg, const char* message) {
tonyp@3713:   msg->append("[%s] %s c: %u b: %s r: "PTR_FORMAT" u: "SIZE_FORMAT,
tonyp@3028:               _name, message, _count, BOOL_TO_STR(_bot_updates),
tonyp@2715:               _alloc_region, _used_bytes_before);
tonyp@2715: }
tonyp@2715: 
tonyp@2715: void G1AllocRegion::init() {
tonyp@2715:   trace("initializing");
tonyp@2715:   assert(_alloc_region == NULL && _used_bytes_before == 0,
tonyp@2715:          ar_ext_msg(this, "pre-condition"));
tonyp@3028:   assert(_dummy_region != NULL, ar_ext_msg(this, "should have been set"));
tonyp@2715:   _alloc_region = _dummy_region;
tonyp@3028:   _count = 0;
tonyp@2715:   trace("initialized");
tonyp@2715: }
tonyp@2715: 
tonyp@3028: void G1AllocRegion::set(HeapRegion* alloc_region) {
tonyp@3028:   trace("setting");
tonyp@3028:   // We explicitly check that the region is not empty to make sure we
tonyp@3028:   // maintain the "the alloc region cannot be empty" invariant.
tonyp@3028:   assert(alloc_region != NULL && !alloc_region->is_empty(),
tonyp@3028:          ar_ext_msg(this, "pre-condition"));
tonyp@3028:   assert(_alloc_region == _dummy_region &&
tonyp@3028:          _used_bytes_before == 0 && _count == 0,
tonyp@3028:          ar_ext_msg(this, "pre-condition"));
tonyp@3028: 
tonyp@3028:   _used_bytes_before = alloc_region->used();
tonyp@3028:   _alloc_region = alloc_region;
tonyp@3028:   _count += 1;
tonyp@3028:   trace("set");
tonyp@3028: }
tonyp@3028: 
tonyp@2715: HeapRegion* G1AllocRegion::release() {
tonyp@2715:   trace("releasing");
tonyp@2715:   HeapRegion* alloc_region = _alloc_region;
tonyp@2715:   retire(false /* fill_up */);
tonyp@3028:   assert(_alloc_region == _dummy_region,
tonyp@3028:          ar_ext_msg(this, "post-condition of retire()"));
tonyp@2715:   _alloc_region = NULL;
tonyp@2715:   trace("released");
tonyp@2715:   return (alloc_region == _dummy_region) ? NULL : alloc_region;
tonyp@2715: }
tonyp@2715: 
tonyp@2715: #if G1_ALLOC_REGION_TRACING
tonyp@2715: void G1AllocRegion::trace(const char* str, size_t word_size, HeapWord* result) {
tonyp@2715:   // All the calls to trace that set either just the size or the size
tonyp@2715:   // and the result are considered part of level 2 tracing and are
tonyp@2715:   // skipped during level 1 tracing.
tonyp@2715:   if ((word_size == 0 && result == NULL) || (G1_ALLOC_REGION_TRACING > 1)) {
tonyp@2715:     const size_t buffer_length = 128;
tonyp@2715:     char hr_buffer[buffer_length];
tonyp@2715:     char rest_buffer[buffer_length];
tonyp@2715: 
tonyp@2715:     HeapRegion* alloc_region = _alloc_region;
tonyp@2715:     if (alloc_region == NULL) {
tonyp@2715:       jio_snprintf(hr_buffer, buffer_length, "NULL");
tonyp@2715:     } else if (alloc_region == _dummy_region) {
tonyp@2715:       jio_snprintf(hr_buffer, buffer_length, "DUMMY");
tonyp@2715:     } else {
tonyp@2715:       jio_snprintf(hr_buffer, buffer_length,
tonyp@2715:                    HR_FORMAT, HR_FORMAT_PARAMS(alloc_region));
tonyp@2715:     }
tonyp@2715: 
tonyp@2715:     if (G1_ALLOC_REGION_TRACING > 1) {
tonyp@2715:       if (result != NULL) {
tonyp@2715:         jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT" "PTR_FORMAT,
tonyp@2715:                      word_size, result);
tonyp@2715:       } else if (word_size != 0) {
tonyp@2715:         jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT, word_size);
tonyp@2715:       } else {
tonyp@2715:         jio_snprintf(rest_buffer, buffer_length, "");
tonyp@2715:       }
tonyp@2715:     } else {
tonyp@2715:       jio_snprintf(rest_buffer, buffer_length, "");
tonyp@2715:     }
tonyp@2715: 
tonyp@3713:     tty->print_cr("[%s] %u %s : %s %s",
tonyp@3028:                   _name, _count, hr_buffer, str, rest_buffer);
tonyp@2715:   }
tonyp@2715: }
tonyp@2715: #endif // G1_ALLOC_REGION_TRACING
tonyp@2715: 
tonyp@2715: G1AllocRegion::G1AllocRegion(const char* name,
tonyp@2715:                              bool bot_updates)
tonyp@2715:   : _name(name), _bot_updates(bot_updates),
tonyp@3028:     _alloc_region(NULL), _count(0), _used_bytes_before(0) { }
tonyp@2715: