jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1AllocRegion.cpp@abdfc822206f (annotated)

src/share/vm/gc_implementation/g1/g1AllocRegion.cpp@abdfc822206f (annotated)

src/share/vm/gc_implementation/g1/g1AllocRegion.cpp

Wed, 30 Mar 2011 10:26:59 -0400

author: tonyp
date: Wed, 30 Mar 2011 10:26:59 -0400
changeset 2715: abdfc822206f
child 3028: f44782f04dd4
permissions: -rw-r--r--

7023069: G1: Introduce symmetric locking in the slow allocation path
7023151: G1: refactor the code that operates on _cur_alloc_region to be re-used for allocs by the GC threads
7018286: G1: humongous allocation attempts should take the GC locker into account
Summary: First, this change replaces the asymmetric locking scheme in the G1 slow alloc path by a summetric one. Second, it factors out the code that operates on _cur_alloc_region so that it can be re-used for allocations by the GC threads in the future.
Reviewed-by: stefank, brutisso, johnc

 /*
  * Copyright (c) 2011, 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/g1AllocRegion.inline.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 G1CollectedHeap* G1AllocRegion::_g1h = NULL;
 HeapRegion* G1AllocRegion::_dummy_region = NULL;
 void G1AllocRegion::setup(G1CollectedHeap* g1h, HeapRegion* dummy_region) {
   assert(_dummy_region == NULL, "should be set once");
   assert(dummy_region != NULL, "pre-condition");
   assert(dummy_region->free() == 0, "pre-condition");
   // Make sure that any allocation attempt on this region will fail
   // and will not trigger any asserts.
   assert(allocate(dummy_region, 1, false) == NULL, "should fail");
   assert(par_allocate(dummy_region, 1, false) == NULL, "should fail");
   assert(allocate(dummy_region, 1, true) == NULL, "should fail");
   assert(par_allocate(dummy_region, 1, true) == NULL, "should fail");
   _g1h = g1h;
   _dummy_region = dummy_region;
 }
 void G1AllocRegion::fill_up_remaining_space(HeapRegion* alloc_region,
                                             bool bot_updates) {
   assert(alloc_region != NULL && alloc_region != _dummy_region,
          "pre-condition");
   // Other threads might still be trying to allocate using a CAS out
   // of the region we are trying to retire, as they can do so without
   // holding the lock. So, we first have to make sure that noone else
   // can allocate out of it by doing a maximal allocation. Even if our
   // CAS attempt fails a few times, we'll succeed sooner or later
   // given that failed CAS attempts mean that the region is getting
   // closed to being full.
   size_t free_word_size = alloc_region->free() / HeapWordSize;
   // This is the minimum free chunk we can turn into a dummy
   // object. If the free space falls below this, then noone can
   // allocate in this region anyway (all allocation requests will be
   // of a size larger than this) so we won't have to perform the dummy
   // allocation.
   size_t min_word_size_to_fill = CollectedHeap::min_fill_size();
   while (free_word_size >= min_word_size_to_fill) {
     HeapWord* dummy = par_allocate(alloc_region, free_word_size, bot_updates);
     if (dummy != NULL) {
       // If the allocation was successful we should fill in the space.
       CollectedHeap::fill_with_object(dummy, free_word_size);
       alloc_region->set_pre_dummy_top(dummy);
       break;
     }
     free_word_size = alloc_region->free() / HeapWordSize;
     // It's also possible that someone else beats us to the
     // allocation and they fill up the region. In that case, we can
     // just get out of the loop.
   }
   assert(alloc_region->free() / HeapWordSize < min_word_size_to_fill,
          "post-condition");
 }
 void G1AllocRegion::retire(bool fill_up) {
   assert(_alloc_region != NULL, ar_ext_msg(this, "not initialized properly"));
   trace("retiring");
   HeapRegion* alloc_region = _alloc_region;
   if (alloc_region != _dummy_region) {
     // We never have to check whether the active region is empty or not,
     // and potentially free it if it is, given that it's guaranteed that
     // it will never be empty.
     assert(!alloc_region->is_empty(),
            ar_ext_msg(this, "the alloc region should never be empty"));
     if (fill_up) {
       fill_up_remaining_space(alloc_region, _bot_updates);
     }
     assert(alloc_region->used() >= _used_bytes_before,
            ar_ext_msg(this, "invariant"));
     size_t allocated_bytes = alloc_region->used() - _used_bytes_before;
     retire_region(alloc_region, allocated_bytes);
     _used_bytes_before = 0;
     _alloc_region = _dummy_region;
   }
   trace("retired");
 }
 HeapWord* G1AllocRegion::new_alloc_region_and_allocate(size_t word_size,
                                                        bool force) {
   assert(_alloc_region == _dummy_region, ar_ext_msg(this, "pre-condition"));
   assert(_used_bytes_before == 0, ar_ext_msg(this, "pre-condition"));
   trace("attempting region allocation");
   HeapRegion* new_alloc_region = allocate_new_region(word_size, force);
   if (new_alloc_region != NULL) {
     new_alloc_region->reset_pre_dummy_top();
     // Need to do this before the allocation
     _used_bytes_before = new_alloc_region->used();
     HeapWord* result = allocate(new_alloc_region, word_size, _bot_updates);
     assert(result != NULL, ar_ext_msg(this, "the allocation should succeeded"));
     OrderAccess::storestore();
     // Note that we first perform the allocation and then we store the
     // region in _alloc_region. This is the reason why an active region
     // can never be empty.
     _alloc_region = new_alloc_region;
     trace("region allocation successful");
     return result;
   } else {
     trace("region allocation failed");
     return NULL;
   }
   ShouldNotReachHere();
 }
 void G1AllocRegion::fill_in_ext_msg(ar_ext_msg* msg, const char* message) {
   msg->append("[%s] %s b: %s r: "PTR_FORMAT" u: "SIZE_FORMAT,
               _name, message, BOOL_TO_STR(_bot_updates),
               _alloc_region, _used_bytes_before);
 }
 void G1AllocRegion::init() {
   trace("initializing");
   assert(_alloc_region == NULL && _used_bytes_before == 0,
          ar_ext_msg(this, "pre-condition"));
   assert(_dummy_region != NULL, "should have been set");
   _alloc_region = _dummy_region;
   trace("initialized");
 }
 HeapRegion* G1AllocRegion::release() {
   trace("releasing");
   HeapRegion* alloc_region = _alloc_region;
   retire(false /* fill_up */);
   assert(_alloc_region == _dummy_region, "post-condition of retire()");
   _alloc_region = NULL;
   trace("released");
   return (alloc_region == _dummy_region) ? NULL : alloc_region;
 }
 #if G1_ALLOC_REGION_TRACING
 void G1AllocRegion::trace(const char* str, size_t word_size, HeapWord* result) {
   // All the calls to trace that set either just the size or the size
   // and the result are considered part of level 2 tracing and are
   // skipped during level 1 tracing.
   if ((word_size == 0 && result == NULL) || (G1_ALLOC_REGION_TRACING > 1)) {
     const size_t buffer_length = 128;
     char hr_buffer[buffer_length];
     char rest_buffer[buffer_length];
     HeapRegion* alloc_region = _alloc_region;
     if (alloc_region == NULL) {
       jio_snprintf(hr_buffer, buffer_length, "NULL");
     } else if (alloc_region == _dummy_region) {
       jio_snprintf(hr_buffer, buffer_length, "DUMMY");
     } else {
       jio_snprintf(hr_buffer, buffer_length,
                    HR_FORMAT, HR_FORMAT_PARAMS(alloc_region));
     }
     if (G1_ALLOC_REGION_TRACING > 1) {
       if (result != NULL) {
         jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT" "PTR_FORMAT,
                      word_size, result);
       } else if (word_size != 0) {
         jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT, word_size);
       } else {
         jio_snprintf(rest_buffer, buffer_length, "");
       }
     } else {
       jio_snprintf(rest_buffer, buffer_length, "");
     }
     tty->print_cr("[%s] %s : %s %s", _name, hr_buffer, str, rest_buffer);
   }
 }
 #endif // G1_ALLOC_REGION_TRACING
 G1AllocRegion::G1AllocRegion(const char* name,
                              bool bot_updates)
   : _name(name), _bot_updates(bot_updates),
     _alloc_region(NULL), _used_bytes_before(0) { }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1AllocRegion.cpp@abdfc822206f (annotated)

src/share/vm/gc_implementation/g1/g1AllocRegion.cpp