hotspot/src/share/vm/gc_implementation/shared/mutableNUMASpace.cpp
changeset 1 489c9b5090e2
child 388 bcc631c5bbec
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/shared/mutableNUMASpace.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,790 @@
+
+/*
+ * Copyright 2006-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_mutableNUMASpace.cpp.incl"
+
+
+MutableNUMASpace::MutableNUMASpace() {
+  _lgrp_spaces = new (ResourceObj::C_HEAP) GrowableArray<LGRPSpace*>(0, true);
+  _page_size = os::vm_page_size();
+  _adaptation_cycles = 0;
+  _samples_count = 0;
+  update_layout(true);
+}
+
+MutableNUMASpace::~MutableNUMASpace() {
+  for (int i = 0; i < lgrp_spaces()->length(); i++) {
+    delete lgrp_spaces()->at(i);
+  }
+  delete lgrp_spaces();
+}
+
+void MutableNUMASpace::mangle_unused_area() {
+  for (int i = 0; i < lgrp_spaces()->length(); i++) {
+    LGRPSpace *ls = lgrp_spaces()->at(i);
+    MutableSpace *s = ls->space();
+    HeapWord *top = MAX2((HeapWord*)round_down((intptr_t)s->top(), page_size()), s->bottom());
+    if (top < s->end()) {
+      ls->add_invalid_region(MemRegion(top, s->end()));
+    }
+    s->mangle_unused_area();
+  }
+}
+
+// There may be unallocated holes in the middle chunks
+// that should be filled with dead objects to ensure parseability.
+void MutableNUMASpace::ensure_parsability() {
+  for (int i = 0; i < lgrp_spaces()->length(); i++) {
+    LGRPSpace *ls = lgrp_spaces()->at(i);
+    MutableSpace *s = ls->space();
+    if (!s->contains(top())) {
+      if (s->free_in_words() > 0) {
+        SharedHeap::fill_region_with_object(MemRegion(s->top(), s->end()));
+        size_t area_touched_words = pointer_delta(s->end(), s->top(), sizeof(HeapWordSize));
+#ifndef ASSERT
+        if (!ZapUnusedHeapArea) {
+          area_touched_words = MIN2((size_t)align_object_size(typeArrayOopDesc::header_size(T_INT)),
+                                    area_touched_words);
+        }
+#endif
+        MemRegion invalid;
+        HeapWord *crossing_start = (HeapWord*)round_to((intptr_t)s->top(), os::vm_page_size());
+        HeapWord *crossing_end = (HeapWord*)round_to((intptr_t)(s->top() + area_touched_words),
+                                                     os::vm_page_size());
+        if (crossing_start != crossing_end) {
+          // If object header crossed a small page boundary we mark the area
+          // as invalid rounding it to a page_size().
+          HeapWord *start = MAX2((HeapWord*)round_down((intptr_t)s->top(), page_size()), s->bottom());
+          HeapWord *end = MIN2((HeapWord*)round_to((intptr_t)(s->top() + area_touched_words), page_size()),
+                               s->end());
+          invalid = MemRegion(start, end);
+        }
+
+        ls->add_invalid_region(invalid);
+        s->set_top(s->end());
+      }
+    } else {
+#ifdef ASSERT
+      MemRegion invalid(s->top(), s->end());
+      ls->add_invalid_region(invalid);
+#else
+      if (ZapUnusedHeapArea) {
+        MemRegion invalid(s->top(), s->end());
+        ls->add_invalid_region(invalid);
+      } else break;
+#endif
+    }
+  }
+}
+
+size_t MutableNUMASpace::used_in_words() const {
+  size_t s = 0;
+  for (int i = 0; i < lgrp_spaces()->length(); i++) {
+    s += lgrp_spaces()->at(i)->space()->used_in_words();
+  }
+  return s;
+}
+
+size_t MutableNUMASpace::free_in_words() const {
+  size_t s = 0;
+  for (int i = 0; i < lgrp_spaces()->length(); i++) {
+    s += lgrp_spaces()->at(i)->space()->free_in_words();
+  }
+  return s;
+}
+
+
+size_t MutableNUMASpace::tlab_capacity(Thread *thr) const {
+  guarantee(thr != NULL, "No thread");
+  int lgrp_id = thr->lgrp_id();
+  assert(lgrp_id != -1, "No lgrp_id set");
+  int i = lgrp_spaces()->find(&lgrp_id, LGRPSpace::equals);
+  if (i == -1) {
+    return 0;
+  }
+  return lgrp_spaces()->at(i)->space()->capacity_in_bytes();
+}
+
+size_t MutableNUMASpace::unsafe_max_tlab_alloc(Thread *thr) const {
+  guarantee(thr != NULL, "No thread");
+  int lgrp_id = thr->lgrp_id();
+  assert(lgrp_id != -1, "No lgrp_id set");
+  int i = lgrp_spaces()->find(&lgrp_id, LGRPSpace::equals);
+  if (i == -1) {
+    return 0;
+  }
+  return lgrp_spaces()->at(i)->space()->free_in_bytes();
+}
+
+// Check if the NUMA topology has changed. Add and remove spaces if needed.
+// The update can be forced by setting the force parameter equal to true.
+bool MutableNUMASpace::update_layout(bool force) {
+  // Check if the topology had changed.
+  bool changed = os::numa_topology_changed();
+  if (force || changed) {
+    // Compute lgrp intersection. Add/remove spaces.
+    int lgrp_limit = (int)os::numa_get_groups_num();
+    int *lgrp_ids = NEW_C_HEAP_ARRAY(int, lgrp_limit);
+    int lgrp_num = (int)os::numa_get_leaf_groups(lgrp_ids, lgrp_limit);
+    assert(lgrp_num > 0, "There should be at least one locality group");
+    // Add new spaces for the new nodes
+    for (int i = 0; i < lgrp_num; i++) {
+      bool found = false;
+      for (int j = 0; j < lgrp_spaces()->length(); j++) {
+        if (lgrp_spaces()->at(j)->lgrp_id() == lgrp_ids[i]) {
+          found = true;
+          break;
+        }
+      }
+      if (!found) {
+        lgrp_spaces()->append(new LGRPSpace(lgrp_ids[i]));
+      }
+    }
+
+    // Remove spaces for the removed nodes.
+    for (int i = 0; i < lgrp_spaces()->length();) {
+      bool found = false;
+      for (int j = 0; j < lgrp_num; j++) {
+        if (lgrp_spaces()->at(i)->lgrp_id() == lgrp_ids[j]) {
+          found = true;
+          break;
+        }
+      }
+      if (!found) {
+        delete lgrp_spaces()->at(i);
+        lgrp_spaces()->remove_at(i);
+      } else {
+        i++;
+      }
+    }
+
+    FREE_C_HEAP_ARRAY(int, lgrp_ids);
+
+    if (changed) {
+      for (JavaThread *thread = Threads::first(); thread; thread = thread->next()) {
+        thread->set_lgrp_id(-1);
+      }
+    }
+    return true;
+  }
+  return false;
+}
+
+// Bias region towards the first-touching lgrp. Set the right page sizes.
+void MutableNUMASpace::bias_region(MemRegion mr) {
+  HeapWord *start = (HeapWord*)round_to((intptr_t)mr.start(), page_size());
+  HeapWord *end = (HeapWord*)round_down((intptr_t)mr.end(), page_size());
+  if (end > start) {
+    MemRegion aligned_region(start, end);
+    assert((intptr_t)aligned_region.start()     % page_size() == 0 &&
+           (intptr_t)aligned_region.byte_size() % page_size() == 0, "Bad alignment");
+    assert(region().contains(aligned_region), "Sanity");
+    os::free_memory((char*)aligned_region.start(), aligned_region.byte_size());
+    os::realign_memory((char*)aligned_region.start(), aligned_region.byte_size(), page_size());
+    os::numa_make_local((char*)aligned_region.start(), aligned_region.byte_size());
+  }
+}
+
+// Free all pages in the region.
+void MutableNUMASpace::free_region(MemRegion mr) {
+  HeapWord *start = (HeapWord*)round_to((intptr_t)mr.start(), page_size());
+  HeapWord *end = (HeapWord*)round_down((intptr_t)mr.end(), page_size());
+  if (end > start) {
+    MemRegion aligned_region(start, end);
+    assert((intptr_t)aligned_region.start()     % page_size() == 0 &&
+           (intptr_t)aligned_region.byte_size() % page_size() == 0, "Bad alignment");
+    assert(region().contains(aligned_region), "Sanity");
+    os::free_memory((char*)aligned_region.start(), aligned_region.byte_size());
+  }
+}
+
+// Update space layout. Perform adaptation.
+void MutableNUMASpace::update() {
+  if (update_layout(false)) {
+    // If the topology has changed, make all chunks zero-sized.
+    for (int i = 0; i < lgrp_spaces()->length(); i++) {
+      MutableSpace *s = lgrp_spaces()->at(i)->space();
+      s->set_end(s->bottom());
+      s->set_top(s->bottom());
+    }
+    initialize(region(), true);
+  } else {
+    bool should_initialize = false;
+    for (int i = 0; i < lgrp_spaces()->length(); i++) {
+      if (!lgrp_spaces()->at(i)->invalid_region().is_empty()) {
+        should_initialize = true;
+        break;
+      }
+    }
+
+    if (should_initialize ||
+        (UseAdaptiveNUMAChunkSizing && adaptation_cycles() < samples_count())) {
+      initialize(region(), true);
+    }
+  }
+
+  if (NUMAStats) {
+    for (int i = 0; i < lgrp_spaces()->length(); i++) {
+      lgrp_spaces()->at(i)->accumulate_statistics(page_size());
+    }
+  }
+
+  scan_pages(NUMAPageScanRate);
+}
+
+// Scan pages. Free pages that have smaller size or wrong placement.
+void MutableNUMASpace::scan_pages(size_t page_count)
+{
+  size_t pages_per_chunk = page_count / lgrp_spaces()->length();
+  if (pages_per_chunk > 0) {
+    for (int i = 0; i < lgrp_spaces()->length(); i++) {
+      LGRPSpace *ls = lgrp_spaces()->at(i);
+      ls->scan_pages(page_size(), pages_per_chunk);
+    }
+  }
+}
+
+// Accumulate statistics about the allocation rate of each lgrp.
+void MutableNUMASpace::accumulate_statistics() {
+  if (UseAdaptiveNUMAChunkSizing) {
+    for (int i = 0; i < lgrp_spaces()->length(); i++) {
+      lgrp_spaces()->at(i)->sample();
+    }
+    increment_samples_count();
+  }
+
+  if (NUMAStats) {
+    for (int i = 0; i < lgrp_spaces()->length(); i++) {
+      lgrp_spaces()->at(i)->accumulate_statistics(page_size());
+    }
+  }
+}
+
+// Get the current size of a chunk.
+// This function computes the size of the chunk based on the
+// difference between chunk ends. This allows it to work correctly in
+// case the whole space is resized and during the process of adaptive
+// chunk resizing.
+size_t MutableNUMASpace::current_chunk_size(int i) {
+  HeapWord *cur_end, *prev_end;
+  if (i == 0) {
+    prev_end = bottom();
+  } else {
+    prev_end = lgrp_spaces()->at(i - 1)->space()->end();
+  }
+  if (i == lgrp_spaces()->length() - 1) {
+    cur_end = end();
+  } else {
+    cur_end = lgrp_spaces()->at(i)->space()->end();
+  }
+  if (cur_end > prev_end) {
+    return pointer_delta(cur_end, prev_end, sizeof(char));
+  }
+  return 0;
+}
+
+// Return the default chunk size by equally diving the space.
+// page_size() aligned.
+size_t MutableNUMASpace::default_chunk_size() {
+  return base_space_size() / lgrp_spaces()->length() * page_size();
+}
+
+// Produce a new chunk size. page_size() aligned.
+size_t MutableNUMASpace::adaptive_chunk_size(int i, size_t limit) {
+  size_t pages_available = base_space_size();
+  for (int j = 0; j < i; j++) {
+    pages_available -= round_down(current_chunk_size(j), page_size()) / page_size();
+  }
+  pages_available -= lgrp_spaces()->length() - i - 1;
+  assert(pages_available > 0, "No pages left");
+  float alloc_rate = 0;
+  for (int j = i; j < lgrp_spaces()->length(); j++) {
+    alloc_rate += lgrp_spaces()->at(j)->alloc_rate()->average();
+  }
+  size_t chunk_size = 0;
+  if (alloc_rate > 0) {
+    LGRPSpace *ls = lgrp_spaces()->at(i);
+    chunk_size = (size_t)(ls->alloc_rate()->average() * pages_available / alloc_rate) * page_size();
+  }
+  chunk_size = MAX2(chunk_size, page_size());
+
+  if (limit > 0) {
+    limit = round_down(limit, page_size());
+    if (chunk_size > current_chunk_size(i)) {
+      chunk_size = MIN2((off_t)chunk_size, (off_t)current_chunk_size(i) + (off_t)limit);
+    } else {
+      chunk_size = MAX2((off_t)chunk_size, (off_t)current_chunk_size(i) - (off_t)limit);
+    }
+  }
+  assert(chunk_size <= pages_available * page_size(), "Chunk size out of range");
+  return chunk_size;
+}
+
+
+// Return the bottom_region and the top_region. Align them to page_size() boundary.
+// |------------------new_region---------------------------------|
+// |----bottom_region--|---intersection---|------top_region------|
+void MutableNUMASpace::select_tails(MemRegion new_region, MemRegion intersection,
+                                    MemRegion* bottom_region, MemRegion *top_region) {
+  // Is there bottom?
+  if (new_region.start() < intersection.start()) { // Yes
+    // Try to coalesce small pages into a large one.
+    if (UseLargePages && page_size() >= os::large_page_size()) {
+      HeapWord* p = (HeapWord*)round_to((intptr_t) intersection.start(), os::large_page_size());
+      if (new_region.contains(p)
+          && pointer_delta(p, new_region.start(), sizeof(char)) >= os::large_page_size()) {
+        if (intersection.contains(p)) {
+          intersection = MemRegion(p, intersection.end());
+        } else {
+          intersection = MemRegion(p, p);
+        }
+      }
+    }
+    *bottom_region = MemRegion(new_region.start(), intersection.start());
+  } else {
+    *bottom_region = MemRegion();
+  }
+
+  // Is there top?
+  if (intersection.end() < new_region.end()) { // Yes
+    // Try to coalesce small pages into a large one.
+    if (UseLargePages && page_size() >= os::large_page_size()) {
+      HeapWord* p = (HeapWord*)round_down((intptr_t) intersection.end(), os::large_page_size());
+      if (new_region.contains(p)
+          && pointer_delta(new_region.end(), p, sizeof(char)) >= os::large_page_size()) {
+        if (intersection.contains(p)) {
+          intersection = MemRegion(intersection.start(), p);
+        } else {
+          intersection = MemRegion(p, p);
+        }
+      }
+    }
+    *top_region = MemRegion(intersection.end(), new_region.end());
+  } else {
+    *top_region = MemRegion();
+  }
+}
+
+// Try to merge the invalid region with the bottom or top region by decreasing
+// the intersection area. Return the invalid_region aligned to the page_size()
+// boundary if it's inside the intersection. Return non-empty invalid_region
+// if it lies inside the intersection (also page-aligned).
+// |------------------new_region---------------------------------|
+// |----------------|-------invalid---|--------------------------|
+// |----bottom_region--|---intersection---|------top_region------|
+void MutableNUMASpace::merge_regions(MemRegion new_region, MemRegion* intersection,
+                                     MemRegion *invalid_region) {
+  if (intersection->start() >= invalid_region->start() && intersection->contains(invalid_region->end())) {
+    *intersection = MemRegion(invalid_region->end(), intersection->end());
+    *invalid_region = MemRegion();
+  } else
+    if (intersection->end() <= invalid_region->end() && intersection->contains(invalid_region->start())) {
+      *intersection = MemRegion(intersection->start(), invalid_region->start());
+      *invalid_region = MemRegion();
+    } else
+      if (intersection->equals(*invalid_region) || invalid_region->contains(*intersection)) {
+        *intersection = MemRegion(new_region.start(), new_region.start());
+        *invalid_region = MemRegion();
+      } else
+        if (intersection->contains(invalid_region)) {
+            // That's the only case we have to make an additional bias_region() call.
+            HeapWord* start = invalid_region->start();
+            HeapWord* end = invalid_region->end();
+            if (UseLargePages && page_size() >= os::large_page_size()) {
+              HeapWord *p = (HeapWord*)round_down((intptr_t) start, os::large_page_size());
+              if (new_region.contains(p)) {
+                start = p;
+              }
+              p = (HeapWord*)round_to((intptr_t) end, os::large_page_size());
+              if (new_region.contains(end)) {
+                end = p;
+              }
+            }
+            if (intersection->start() > start) {
+              *intersection = MemRegion(start, intersection->end());
+            }
+            if (intersection->end() < end) {
+              *intersection = MemRegion(intersection->start(), end);
+            }
+            *invalid_region = MemRegion(start, end);
+        }
+}
+
+void MutableNUMASpace::initialize(MemRegion mr, bool clear_space) {
+  assert(clear_space, "Reallocation will destory data!");
+  assert(lgrp_spaces()->length() > 0, "There should be at least one space");
+
+  MemRegion old_region = region(), new_region;
+  set_bottom(mr.start());
+  set_end(mr.end());
+  MutableSpace::set_top(bottom());
+
+  // Compute chunk sizes
+  size_t prev_page_size = page_size();
+  set_page_size(UseLargePages ? os::large_page_size() : os::vm_page_size());
+  HeapWord* rounded_bottom = (HeapWord*)round_to((intptr_t) bottom(), page_size());
+  HeapWord* rounded_end = (HeapWord*)round_down((intptr_t) end(), page_size());
+  size_t base_space_size_pages = pointer_delta(rounded_end, rounded_bottom, sizeof(char)) / page_size();
+
+  // Try small pages if the chunk size is too small
+  if (base_space_size_pages / lgrp_spaces()->length() == 0
+      && page_size() > (size_t)os::vm_page_size()) {
+    set_page_size(os::vm_page_size());
+    rounded_bottom = (HeapWord*)round_to((intptr_t) bottom(), page_size());
+    rounded_end = (HeapWord*)round_down((intptr_t) end(), page_size());
+    base_space_size_pages = pointer_delta(rounded_end, rounded_bottom, sizeof(char)) / page_size();
+  }
+  guarantee(base_space_size_pages / lgrp_spaces()->length() > 0, "Space too small");
+  set_base_space_size(base_space_size_pages);
+
+  // Handle space resize
+  MemRegion top_region, bottom_region;
+  if (!old_region.equals(region())) {
+    new_region = MemRegion(rounded_bottom, rounded_end);
+    MemRegion intersection = new_region.intersection(old_region);
+    if (intersection.start() == NULL ||
+        intersection.end() == NULL   ||
+        prev_page_size > page_size()) { // If the page size got smaller we have to change
+                                        // the page size preference for the whole space.
+      intersection = MemRegion(new_region.start(), new_region.start());
+    }
+    select_tails(new_region, intersection, &bottom_region, &top_region);
+    bias_region(bottom_region);
+    bias_region(top_region);
+  }
+
+  // Check if the space layout has changed significantly?
+  // This happens when the space has been resized so that either head or tail
+  // chunk became less than a page.
+  bool layout_valid = UseAdaptiveNUMAChunkSizing          &&
+                      current_chunk_size(0) > page_size() &&
+                      current_chunk_size(lgrp_spaces()->length() - 1) > page_size();
+
+
+  for (int i = 0; i < lgrp_spaces()->length(); i++) {
+    LGRPSpace *ls = lgrp_spaces()->at(i);
+    MutableSpace *s = ls->space();
+    old_region = s->region();
+
+    size_t chunk_byte_size = 0, old_chunk_byte_size = 0;
+    if (i < lgrp_spaces()->length() - 1) {
+      if (!UseAdaptiveNUMAChunkSizing                                ||
+          (UseAdaptiveNUMAChunkSizing && NUMAChunkResizeWeight == 0) ||
+           samples_count() < AdaptiveSizePolicyReadyThreshold) {
+        // No adaptation. Divide the space equally.
+        chunk_byte_size = default_chunk_size();
+      } else
+        if (!layout_valid || NUMASpaceResizeRate == 0) {
+          // Fast adaptation. If no space resize rate is set, resize
+          // the chunks instantly.
+          chunk_byte_size = adaptive_chunk_size(i, 0);
+        } else {
+          // Slow adaptation. Resize the chunks moving no more than
+          // NUMASpaceResizeRate bytes per collection.
+          size_t limit = NUMASpaceResizeRate /
+                         (lgrp_spaces()->length() * (lgrp_spaces()->length() + 1) / 2);
+          chunk_byte_size = adaptive_chunk_size(i, MAX2(limit * (i + 1), page_size()));
+        }
+
+      assert(chunk_byte_size >= page_size(), "Chunk size too small");
+      assert(chunk_byte_size <= capacity_in_bytes(), "Sanity check");
+    }
+
+    if (i == 0) { // Bottom chunk
+      if (i != lgrp_spaces()->length() - 1) {
+        new_region = MemRegion(bottom(), rounded_bottom + (chunk_byte_size >> LogHeapWordSize));
+      } else {
+        new_region = MemRegion(bottom(), end());
+      }
+    } else
+      if (i < lgrp_spaces()->length() - 1) { // Middle chunks
+        MutableSpace *ps = lgrp_spaces()->at(i - 1)->space();
+        new_region = MemRegion(ps->end(),
+                               ps->end() + (chunk_byte_size >> LogHeapWordSize));
+      } else { // Top chunk
+        MutableSpace *ps = lgrp_spaces()->at(i - 1)->space();
+        new_region = MemRegion(ps->end(), end());
+      }
+    guarantee(region().contains(new_region), "Region invariant");
+
+
+    // The general case:
+    // |---------------------|--invalid---|--------------------------|
+    // |------------------new_region---------------------------------|
+    // |----bottom_region--|---intersection---|------top_region------|
+    //                     |----old_region----|
+    // The intersection part has all pages in place we don't need to migrate them.
+    // Pages for the top and bottom part should be freed and then reallocated.
+
+    MemRegion intersection = old_region.intersection(new_region);
+
+    if (intersection.start() == NULL || intersection.end() == NULL) {
+      intersection = MemRegion(new_region.start(), new_region.start());
+    }
+
+    MemRegion invalid_region = ls->invalid_region().intersection(new_region);
+    if (!invalid_region.is_empty()) {
+      merge_regions(new_region, &intersection, &invalid_region);
+      free_region(invalid_region);
+    }
+    select_tails(new_region, intersection, &bottom_region, &top_region);
+    free_region(bottom_region);
+    free_region(top_region);
+
+    // If we clear the region, we would mangle it in debug. That would cause page
+    // allocation in a different place. Hence setting the top directly.
+    s->initialize(new_region, false);
+    s->set_top(s->bottom());
+
+    ls->set_invalid_region(MemRegion());
+
+    set_adaptation_cycles(samples_count());
+  }
+}
+
+// Set the top of the whole space.
+// Mark the the holes in chunks below the top() as invalid.
+void MutableNUMASpace::set_top(HeapWord* value) {
+  bool found_top = false;
+  for (int i = 0; i < lgrp_spaces()->length(); i++) {
+    LGRPSpace *ls = lgrp_spaces()->at(i);
+    MutableSpace *s = ls->space();
+    HeapWord *top = MAX2((HeapWord*)round_down((intptr_t)s->top(), page_size()), s->bottom());
+
+    if (s->contains(value)) {
+      if (top < value && top < s->end()) {
+        ls->add_invalid_region(MemRegion(top, value));
+      }
+      s->set_top(value);
+      found_top = true;
+    } else {
+        if (found_top) {
+            s->set_top(s->bottom());
+        } else {
+            if (top < s->end()) {
+              ls->add_invalid_region(MemRegion(top, s->end()));
+            }
+            s->set_top(s->end());
+        }
+    }
+  }
+  MutableSpace::set_top(value);
+}
+
+void MutableNUMASpace::clear() {
+  MutableSpace::set_top(bottom());
+  for (int i = 0; i < lgrp_spaces()->length(); i++) {
+    lgrp_spaces()->at(i)->space()->clear();
+  }
+}
+
+HeapWord* MutableNUMASpace::allocate(size_t size) {
+  int lgrp_id = Thread::current()->lgrp_id();
+  if (lgrp_id == -1) {
+    lgrp_id = os::numa_get_group_id();
+    Thread::current()->set_lgrp_id(lgrp_id);
+  }
+
+  int i = lgrp_spaces()->find(&lgrp_id, LGRPSpace::equals);
+
+  // It is possible that a new CPU has been hotplugged and
+  // we haven't reshaped the space accordingly.
+  if (i == -1) {
+    i = os::random() % lgrp_spaces()->length();
+  }
+
+  MutableSpace *s = lgrp_spaces()->at(i)->space();
+  HeapWord *p = s->allocate(size);
+
+  if (p != NULL && s->free_in_words() < (size_t)oopDesc::header_size()) {
+    s->set_top(s->top() - size);
+    p = NULL;
+  }
+  if (p != NULL) {
+    if (top() < s->top()) { // Keep _top updated.
+      MutableSpace::set_top(s->top());
+    }
+  }
+  // Make the page allocation happen here.
+  if (p != NULL) {
+    for (HeapWord *i = p; i < p + size; i += os::vm_page_size() >> LogHeapWordSize) {
+      *(int*)i = 0;
+    }
+  }
+
+  return p;
+}
+
+// This version is lock-free.
+HeapWord* MutableNUMASpace::cas_allocate(size_t size) {
+  int lgrp_id = Thread::current()->lgrp_id();
+  if (lgrp_id == -1) {
+    lgrp_id = os::numa_get_group_id();
+    Thread::current()->set_lgrp_id(lgrp_id);
+  }
+
+  int i = lgrp_spaces()->find(&lgrp_id, LGRPSpace::equals);
+  // It is possible that a new CPU has been hotplugged and
+  // we haven't reshaped the space accordingly.
+  if (i == -1) {
+    i = os::random() % lgrp_spaces()->length();
+  }
+  MutableSpace *s = lgrp_spaces()->at(i)->space();
+  HeapWord *p = s->cas_allocate(size);
+  if (p != NULL && s->free_in_words() < (size_t)oopDesc::header_size()) {
+    if (s->cas_deallocate(p, size)) {
+      // We were the last to allocate and created a fragment less than
+      // a minimal object.
+      p = NULL;
+    }
+  }
+  if (p != NULL) {
+    HeapWord* cur_top, *cur_chunk_top = p + size;
+    while ((cur_top = top()) < cur_chunk_top) { // Keep _top updated.
+      if (Atomic::cmpxchg_ptr(cur_chunk_top, top_addr(), cur_top) == cur_top) {
+        break;
+      }
+    }
+  }
+
+  // Make the page allocation happen here.
+  if (p != NULL) {
+    for (HeapWord *i = p; i < p + size; i += os::vm_page_size() >> LogHeapWordSize) {
+      *(int*)i = 0;
+    }
+  }
+  return p;
+}
+
+void MutableNUMASpace::print_short_on(outputStream* st) const {
+  MutableSpace::print_short_on(st);
+  st->print(" (");
+  for (int i = 0; i < lgrp_spaces()->length(); i++) {
+    st->print("lgrp %d: ", lgrp_spaces()->at(i)->lgrp_id());
+    lgrp_spaces()->at(i)->space()->print_short_on(st);
+    if (i < lgrp_spaces()->length() - 1) {
+      st->print(", ");
+    }
+  }
+  st->print(")");
+}
+
+void MutableNUMASpace::print_on(outputStream* st) const {
+  MutableSpace::print_on(st);
+  for (int i = 0; i < lgrp_spaces()->length(); i++) {
+    LGRPSpace *ls = lgrp_spaces()->at(i);
+    st->print("    lgrp %d", ls->lgrp_id());
+    ls->space()->print_on(st);
+    if (NUMAStats) {
+      st->print("    local/remote/unbiased/uncommitted: %dK/%dK/%dK/%dK, large/small pages: %d/%d\n",
+                ls->space_stats()->_local_space / K,
+                ls->space_stats()->_remote_space / K,
+                ls->space_stats()->_unbiased_space / K,
+                ls->space_stats()->_uncommited_space / K,
+                ls->space_stats()->_large_pages,
+                ls->space_stats()->_small_pages);
+    }
+  }
+}
+
+void MutableNUMASpace::verify(bool allow_dirty) const {
+ for (int i = 0; i < lgrp_spaces()->length(); i++) {
+    lgrp_spaces()->at(i)->space()->verify(allow_dirty);
+  }
+}
+
+// Scan pages and gather stats about page placement and size.
+void MutableNUMASpace::LGRPSpace::accumulate_statistics(size_t page_size) {
+  clear_space_stats();
+  char *start = (char*)round_to((intptr_t) space()->bottom(), page_size);
+  char* end = (char*)round_down((intptr_t) space()->end(), page_size);
+  if (start < end) {
+    for (char *p = start; p < end;) {
+      os::page_info info;
+      if (os::get_page_info(p, &info)) {
+        if (info.size > 0) {
+          if (info.size > (size_t)os::vm_page_size()) {
+            space_stats()->_large_pages++;
+          } else {
+            space_stats()->_small_pages++;
+          }
+          if (info.lgrp_id == lgrp_id()) {
+            space_stats()->_local_space += info.size;
+          } else {
+            space_stats()->_remote_space += info.size;
+          }
+          p += info.size;
+        } else {
+          p += os::vm_page_size();
+          space_stats()->_uncommited_space += os::vm_page_size();
+        }
+      } else {
+        return;
+      }
+    }
+  }
+  space_stats()->_unbiased_space = pointer_delta(start, space()->bottom(), sizeof(char)) +
+                                   pointer_delta(space()->end(), end, sizeof(char));
+
+}
+
+// Scan page_count pages and verify if they have the right size and right placement.
+// If invalid pages are found they are freed in hope that subsequent reallocation
+// will be more successful.
+void MutableNUMASpace::LGRPSpace::scan_pages(size_t page_size, size_t page_count)
+{
+  char* range_start = (char*)round_to((intptr_t) space()->bottom(), page_size);
+  char* range_end = (char*)round_down((intptr_t) space()->end(), page_size);
+
+  if (range_start > last_page_scanned() || last_page_scanned() >= range_end) {
+    set_last_page_scanned(range_start);
+  }
+
+  char *scan_start = last_page_scanned();
+  char* scan_end = MIN2(scan_start + page_size * page_count, range_end);
+
+  os::page_info page_expected, page_found;
+  page_expected.size = page_size;
+  page_expected.lgrp_id = lgrp_id();
+
+  char *s = scan_start;
+  while (s < scan_end) {
+    char *e = os::scan_pages(s, (char*)scan_end, &page_expected, &page_found);
+    if (e == NULL) {
+      break;
+    }
+    if (e != scan_end) {
+      if ((page_expected.size != page_size || page_expected.lgrp_id != lgrp_id())
+          && page_expected.size != 0) {
+        os::free_memory(s, pointer_delta(e, s, sizeof(char)));
+      }
+      page_expected = page_found;
+    }
+    s = e;
+  }
+
+  set_last_page_scanned(scan_end);
+}