1 /*
   2  * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/g1/g1PageBasedVirtualSpace.hpp"
  27 #include "gc/shared/workgroup.hpp"
  28 #include "oops/markOop.hpp"
  29 #include "oops/oop.inline.hpp"
  30 #include "runtime/atomic.hpp"
  31 #include "runtime/os.inline.hpp"
  32 #include "services/memTracker.hpp"
  33 #include "utilities/bitMap.inline.hpp"
  34 
  35 G1PageBasedVirtualSpace::G1PageBasedVirtualSpace(ReservedSpace rs, size_t used_size, size_t page_size) :
  36   _low_boundary(NULL), _high_boundary(NULL), _committed(), _page_size(0), _special(false),
  37   _dirty(), _executable(false) {
  38   initialize_with_page_size(rs, used_size, page_size);
  39 }
  40 
  41 void G1PageBasedVirtualSpace::initialize_with_page_size(ReservedSpace rs, size_t used_size, size_t page_size) {
  42   guarantee(rs.is_reserved(), "Given reserved space must have been reserved already.");
  43 
  44   vmassert(_low_boundary == NULL, "VirtualSpace already initialized");
  45   vmassert(page_size > 0, "Page size must be non-zero.");
  46 
  47   guarantee(is_ptr_aligned(rs.base(), page_size),
  48             "Reserved space base " PTR_FORMAT " is not aligned to requested page size " SIZE_FORMAT, p2i(rs.base()), page_size);
  49   guarantee(is_size_aligned(used_size, os::vm_page_size()),
  50             "Given used reserved space size needs to be OS page size aligned (%d bytes) but is " SIZE_FORMAT, os::vm_page_size(), used_size);
  51   guarantee(used_size <= rs.size(),
  52             "Used size of reserved space " SIZE_FORMAT " bytes is smaller than reservation at " SIZE_FORMAT " bytes", used_size, rs.size());
  53   guarantee(is_size_aligned(rs.size(), page_size),
  54             "Expected that the virtual space is size aligned, but " SIZE_FORMAT " is not aligned to page size " SIZE_FORMAT, rs.size(), page_size);
  55 
  56   _low_boundary  = rs.base();
  57   _high_boundary = _low_boundary + used_size;
  58 
  59   _special = rs.special();
  60   _executable = rs.executable();
  61 
  62   _page_size = page_size;
  63 
  64   vmassert(_committed.size() == 0, "virtual space initialized more than once");
  65   BitMap::idx_t size_in_pages = rs.size() / page_size;
  66   _committed.initialize(size_in_pages);
  67   if (_special) {
  68     _dirty.initialize(size_in_pages);
  69   }
  70 
  71   _tail_size = used_size % _page_size;
  72 }
  73 
  74 G1PageBasedVirtualSpace::~G1PageBasedVirtualSpace() {
  75   // This does not release memory it never reserved.
  76   // Caller must release via rs.release();
  77   _low_boundary           = NULL;
  78   _high_boundary          = NULL;
  79   _special                = false;
  80   _executable             = false;
  81   _page_size              = 0;
  82   _tail_size              = 0;
  83 }
  84 
  85 size_t G1PageBasedVirtualSpace::committed_size() const {
  86   size_t result = _committed.count_one_bits() * _page_size;
  87   // The last page might not be in full.
  88   if (is_last_page_partial() && _committed.at(_committed.size() - 1)) {
  89     result -= _page_size - _tail_size;
  90   }
  91   return result;
  92 }
  93 
  94 size_t G1PageBasedVirtualSpace::reserved_size() const {
  95   return pointer_delta(_high_boundary, _low_boundary, sizeof(char));
  96 }
  97 
  98 size_t G1PageBasedVirtualSpace::uncommitted_size()  const {
  99   return reserved_size() - committed_size();
 100 }
 101 
 102 size_t G1PageBasedVirtualSpace::addr_to_page_index(char* addr) const {
 103   return (addr - _low_boundary) / _page_size;
 104 }
 105 
 106 bool G1PageBasedVirtualSpace::is_area_committed(size_t start_page, size_t size_in_pages) const {
 107   size_t end_page = start_page + size_in_pages;
 108   return _committed.get_next_zero_offset(start_page, end_page) >= end_page;
 109 }
 110 
 111 bool G1PageBasedVirtualSpace::is_area_uncommitted(size_t start_page, size_t size_in_pages) const {
 112   size_t end_page = start_page + size_in_pages;
 113   return _committed.get_next_one_offset(start_page, end_page) >= end_page;
 114 }
 115 
 116 char* G1PageBasedVirtualSpace::page_start(size_t index) const {
 117   return _low_boundary + index * _page_size;
 118 }
 119 
 120 bool G1PageBasedVirtualSpace::is_after_last_page(size_t index) const {
 121   guarantee(index <= _committed.size(),
 122             "Given boundary page " SIZE_FORMAT " is beyond managed page count " SIZE_FORMAT, index, _committed.size());
 123   return index == _committed.size();
 124 }
 125 
 126 void G1PageBasedVirtualSpace::commit_preferred_pages(size_t start, size_t num_pages) {
 127   vmassert(num_pages > 0, "No full pages to commit");
 128   vmassert(start + num_pages <= _committed.size(),
 129            "Tried to commit area from page " SIZE_FORMAT " to page " SIZE_FORMAT " "
 130            "that is outside of managed space of " SIZE_FORMAT " pages",
 131            start, start + num_pages, _committed.size());
 132 
 133   char* start_addr = page_start(start);
 134   size_t size = num_pages * _page_size;
 135 
 136   os::commit_memory_or_exit(start_addr, size, _page_size, _executable,
 137                             err_msg("Failed to commit area from " PTR_FORMAT " to " PTR_FORMAT " of length " SIZE_FORMAT ".",
 138                             p2i(start_addr), p2i(start_addr + size), size));
 139 }
 140 
 141 void G1PageBasedVirtualSpace::commit_tail() {
 142   vmassert(_tail_size > 0, "The size of the tail area must be > 0 when reaching here");
 143 
 144   char* const aligned_end_address = align_ptr_down(_high_boundary, _page_size);
 145   os::commit_memory_or_exit(aligned_end_address, _tail_size, os::vm_page_size(), _executable,
 146                             err_msg("Failed to commit tail area from " PTR_FORMAT " to " PTR_FORMAT " of length " SIZE_FORMAT ".",
 147                             p2i(aligned_end_address), p2i(_high_boundary), _tail_size));
 148 }
 149 
 150 void G1PageBasedVirtualSpace::commit_internal(size_t start_page, size_t end_page) {
 151   guarantee(start_page < end_page,
 152             "Given start page " SIZE_FORMAT " is larger or equal to end page " SIZE_FORMAT, start_page, end_page);
 153   guarantee(end_page <= _committed.size(),
 154             "Given end page " SIZE_FORMAT " is beyond end of managed page amount of " SIZE_FORMAT, end_page, _committed.size());
 155 
 156   size_t pages = end_page - start_page;
 157   bool need_to_commit_tail = is_after_last_page(end_page) && is_last_page_partial();
 158 
 159   // If we have to commit some (partial) tail area, decrease the amount of pages to avoid
 160   // committing that in the full-page commit code.
 161   if (need_to_commit_tail) {
 162     pages--;
 163   }
 164 
 165   if (pages > 0) {
 166     commit_preferred_pages(start_page, pages);
 167   }
 168 
 169   if (need_to_commit_tail) {
 170     commit_tail();
 171   }
 172 }
 173 
 174 char* G1PageBasedVirtualSpace::bounded_end_addr(size_t end_page) const {
 175   return MIN2(_high_boundary, page_start(end_page));
 176 }
 177 
 178 void G1PageBasedVirtualSpace::pretouch_internal(size_t start_page, size_t end_page) {
 179   guarantee(start_page < end_page,
 180             "Given start page " SIZE_FORMAT " is larger or equal to end page " SIZE_FORMAT, start_page, end_page);
 181 
 182   os::pretouch_memory(page_start(start_page), bounded_end_addr(end_page), _page_size);
 183 }
 184 
 185 bool G1PageBasedVirtualSpace::commit(size_t start_page, size_t size_in_pages) {
 186   // We need to make sure to commit all pages covered by the given area.
 187   guarantee(is_area_uncommitted(start_page, size_in_pages), "Specified area is not uncommitted");
 188 
 189   bool zero_filled = true;
 190   size_t end_page = start_page + size_in_pages;
 191 
 192   if (_special) {
 193     // Check for dirty pages and update zero_filled if any found.
 194     if (_dirty.get_next_one_offset(start_page, end_page) < end_page) {
 195       zero_filled = false;
 196       _dirty.clear_range(start_page, end_page);
 197     }
 198   } else {
 199     commit_internal(start_page, end_page);
 200   }
 201   _committed.set_range(start_page, end_page);
 202 
 203   return zero_filled;
 204 }
 205 
 206 void G1PageBasedVirtualSpace::uncommit_internal(size_t start_page, size_t end_page) {
 207   guarantee(start_page < end_page,
 208             "Given start page " SIZE_FORMAT " is larger or equal to end page " SIZE_FORMAT, start_page, end_page);
 209 
 210   char* start_addr = page_start(start_page);
 211   os::uncommit_memory(start_addr, pointer_delta(bounded_end_addr(end_page), start_addr, sizeof(char)));
 212 }
 213 
 214 void G1PageBasedVirtualSpace::uncommit(size_t start_page, size_t size_in_pages) {
 215   guarantee(is_area_committed(start_page, size_in_pages), "checking");
 216 
 217   size_t end_page = start_page + size_in_pages;
 218   if (_special) {
 219     // Mark that memory is dirty. If committed again the memory might
 220     // need to be cleared explicitly.
 221     _dirty.set_range(start_page, end_page);
 222   } else {
 223     uncommit_internal(start_page, end_page);
 224   }
 225 
 226   _committed.clear_range(start_page, end_page);
 227 }
 228 
 229 class G1PretouchTask : public AbstractGangTask {
 230 private:
 231   char* volatile _cur_addr;
 232   char* const _start_addr;
 233   char* const _end_addr;
 234   size_t const _page_size;
 235 public:
 236   G1PretouchTask(char* start_address, char* end_address, size_t page_size) :
 237     AbstractGangTask("G1 PreTouch",
 238                      Universe::is_fully_initialized() &&
 239                      Thread::current()->is_Named_thread() ? GCId::current_raw() :
 240                                                             // During VM initialization there is
 241                                                             // no GC cycle that this task can be
 242                                                             // associated with.
 243                                                             GCId::undefined()),
 244     _cur_addr(start_address),
 245     _start_addr(start_address),
 246     _end_addr(end_address),
 247     _page_size(page_size) {
 248   }
 249 
 250   virtual void work(uint worker_id) {
 251     size_t const actual_chunk_size = MAX2(chunk_size(), _page_size);
 252     while (true) {
 253       char* touch_addr = (char*)Atomic::add_ptr((intptr_t)actual_chunk_size, (volatile void*) &_cur_addr) - actual_chunk_size;
 254       if (touch_addr < _start_addr || touch_addr >= _end_addr) {
 255         break;
 256       }
 257       char* end_addr = touch_addr + MIN2(actual_chunk_size, pointer_delta(_end_addr, touch_addr, sizeof(char)));
 258       os::pretouch_memory(touch_addr, end_addr, _page_size);
 259     }
 260   }
 261 
 262   static size_t chunk_size() { return PreTouchParallelChunkSize; }
 263 };
 264 
 265 void G1PageBasedVirtualSpace::pretouch(size_t start_page, size_t size_in_pages, WorkGang* pretouch_gang) {
 266   G1PretouchTask cl(page_start(start_page), bounded_end_addr(start_page + size_in_pages), _page_size);
 267 
 268   if (pretouch_gang != NULL) {
 269     size_t num_chunks = MAX2((size_t)1, size_in_pages * _page_size / MAX2(G1PretouchTask::chunk_size(), _page_size));
 270 
 271     uint num_workers = MIN2((uint)num_chunks, pretouch_gang->active_workers());
 272     log_debug(gc, heap)("Running %s with %u workers for " SIZE_FORMAT " work units pre-touching " SIZE_FORMAT "B.",
 273                         cl.name(), num_workers, num_chunks, size_in_pages * _page_size);
 274     pretouch_gang->run_task(&cl, num_workers);
 275   } else {
 276     log_debug(gc, heap)("Running %s pre-touching " SIZE_FORMAT "B.",
 277                         cl.name(), size_in_pages * _page_size);
 278     cl.work(0);
 279   }
 280 }
 281 
 282 bool G1PageBasedVirtualSpace::contains(const void* p) const {
 283   return _low_boundary <= (const char*) p && (const char*) p < _high_boundary;
 284 }
 285 
 286 #ifndef PRODUCT
 287 void G1PageBasedVirtualSpace::print_on(outputStream* out) {
 288   out->print   ("Virtual space:");
 289   if (_special) out->print(" (pinned in memory)");
 290   out->cr();
 291   out->print_cr(" - committed: " SIZE_FORMAT, committed_size());
 292   out->print_cr(" - reserved:  " SIZE_FORMAT, reserved_size());
 293   out->print_cr(" - preferred page size: " SIZE_FORMAT, _page_size);
 294   out->print_cr(" - [low_b, high_b]: [" PTR_FORMAT ", " PTR_FORMAT "]",  p2i(_low_boundary), p2i(_high_boundary));
 295 }
 296 
 297 void G1PageBasedVirtualSpace::print() {
 298   print_on(tty);
 299 }
 300 #endif