jdk-24/src/hotspot/share/gc/z/zObjectAllocator.cpp

/*
 * Copyright (c) 2015, 2019, 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/z/zCollectedHeap.hpp"
#include "gc/z/zGlobals.hpp"
#include "gc/z/zHeap.inline.hpp"
#include "gc/z/zHeuristics.hpp"
#include "gc/z/zObjectAllocator.hpp"
#include "gc/z/zPage.inline.hpp"
#include "gc/z/zStat.hpp"
#include "gc/z/zThread.inline.hpp"
#include "gc/z/zUtils.inline.hpp"
#include "gc/z/zValue.inline.hpp"
#include "logging/log.hpp"
#include "runtime/atomic.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/thread.hpp"
#include "runtime/threadSMR.hpp"
#include "utilities/align.hpp"
#include "utilities/debug.hpp"

static const ZStatCounter ZCounterUndoObjectAllocationSucceeded("Memory", "Undo Object Allocation Succeeded", ZStatUnitOpsPerSecond);
static const ZStatCounter ZCounterUndoObjectAllocationFailed("Memory", "Undo Object Allocation Failed", ZStatUnitOpsPerSecond);

ZObjectAllocator::ZObjectAllocator() :
    _use_per_cpu_shared_small_pages(ZHeuristics::use_per_cpu_shared_small_pages()),
    _used(0),
    _undone(0),
    _shared_medium_page(NULL),
    _shared_small_page(NULL),
    _worker_small_page(NULL) {}

ZPage** ZObjectAllocator::shared_small_page_addr() {
  return _use_per_cpu_shared_small_pages ? _shared_small_page.addr() : _shared_small_page.addr(0);
}

ZPage* const* ZObjectAllocator::shared_small_page_addr() const {
  return _use_per_cpu_shared_small_pages ? _shared_small_page.addr() : _shared_small_page.addr(0);
}

ZPage* ZObjectAllocator::alloc_page(uint8_t type, size_t size, ZAllocationFlags flags) {
  ZPage* const page = ZHeap::heap()->alloc_page(type, size, flags);
  if (page != NULL) {
    // Increment used bytes
    Atomic::add(_used.addr(), size);
  }

  return page;
}

void ZObjectAllocator::undo_alloc_page(ZPage* page) {
  // Increment undone bytes
  Atomic::add(_undone.addr(), page->size());

  ZHeap::heap()->undo_alloc_page(page);
}

uintptr_t ZObjectAllocator::alloc_object_in_shared_page(ZPage** shared_page,
                                                        uint8_t page_type,
                                                        size_t page_size,
                                                        size_t size,
                                                        ZAllocationFlags flags) {
  uintptr_t addr = 0;
  ZPage* page = Atomic::load_acquire(shared_page);

  if (page != NULL) {
    addr = page->alloc_object_atomic(size);
  }

  if (addr == 0) {
    // Allocate new page
    ZPage* const new_page = alloc_page(page_type, page_size, flags);
    if (new_page != NULL) {
      // Allocate object before installing the new page
      addr = new_page->alloc_object(size);

    retry:
      // Install new page
      ZPage* const prev_page = Atomic::cmpxchg(shared_page, page, new_page);
      if (prev_page != page) {
        if (prev_page == NULL) {
          // Previous page was retired, retry installing the new page
          page = prev_page;
          goto retry;
        }

        // Another page already installed, try allocation there first
        const uintptr_t prev_addr = prev_page->alloc_object_atomic(size);
        if (prev_addr == 0) {
          // Allocation failed, retry installing the new page
          page = prev_page;
          goto retry;
        }

        // Allocation succeeded in already installed page
        addr = prev_addr;

        // Undo new page allocation
        undo_alloc_page(new_page);
      }
    }
  }

  return addr;
}

uintptr_t ZObjectAllocator::alloc_large_object(size_t size, ZAllocationFlags flags) {
  assert(ZThread::is_java(), "Should be a Java thread");

  uintptr_t addr = 0;

  // Allocate new large page
  const size_t page_size = align_up(size, ZGranuleSize);
  ZPage* const page = alloc_page(ZPageTypeLarge, page_size, flags);
  if (page != NULL) {
    // Allocate the object
    addr = page->alloc_object(size);
  }

  return addr;
}

uintptr_t ZObjectAllocator::alloc_medium_object(size_t size, ZAllocationFlags flags) {
  return alloc_object_in_shared_page(_shared_medium_page.addr(), ZPageTypeMedium, ZPageSizeMedium, size, flags);
}

uintptr_t ZObjectAllocator::alloc_small_object_from_nonworker(size_t size, ZAllocationFlags flags) {
  assert(ZThread::is_java() || ZThread::is_vm() || ZThread::is_runtime_worker(),
         "Should be a Java, VM or Runtime worker thread");

  // Non-worker small page allocation can never use the reserve
  flags.set_no_reserve();

  return alloc_object_in_shared_page(shared_small_page_addr(), ZPageTypeSmall, ZPageSizeSmall, size, flags);
}

uintptr_t ZObjectAllocator::alloc_small_object_from_worker(size_t size, ZAllocationFlags flags) {
  assert(ZThread::is_worker(), "Should be a worker thread");

  ZPage* page = _worker_small_page.get();
  uintptr_t addr = 0;

  if (page != NULL) {
    addr = page->alloc_object(size);
  }

  if (addr == 0) {
    // Allocate new page
    page = alloc_page(ZPageTypeSmall, ZPageSizeSmall, flags);
    if (page != NULL) {
      addr = page->alloc_object(size);
    }
    _worker_small_page.set(page);
  }

  return addr;
}

uintptr_t ZObjectAllocator::alloc_small_object(size_t size, ZAllocationFlags flags) {
  if (flags.worker_thread()) {
    return alloc_small_object_from_worker(size, flags);
  } else {
    return alloc_small_object_from_nonworker(size, flags);
  }
}

uintptr_t ZObjectAllocator::alloc_object(size_t size, ZAllocationFlags flags) {
  if (size <= ZObjectSizeLimitSmall) {
    // Small
    return alloc_small_object(size, flags);
  } else if (size <= ZObjectSizeLimitMedium) {
    // Medium
    return alloc_medium_object(size, flags);
  } else {
    // Large
    return alloc_large_object(size, flags);
  }
}

uintptr_t ZObjectAllocator::alloc_object(size_t size) {
  assert(ZThread::is_java(), "Must be a Java thread");

  ZAllocationFlags flags;
  flags.set_no_reserve();

  return alloc_object(size, flags);
}

uintptr_t ZObjectAllocator::alloc_object_for_relocation(size_t size) {
  assert(ZThread::is_java() || ZThread::is_vm() || ZThread::is_worker() || ZThread::is_runtime_worker(),
         "Unknown thread");

  ZAllocationFlags flags;
  flags.set_relocation();
  flags.set_non_blocking();

  if (ZThread::is_worker()) {
    flags.set_worker_thread();
  }

  return alloc_object(size, flags);
}

bool ZObjectAllocator::undo_alloc_large_object(ZPage* page) {
  assert(page->type() == ZPageTypeLarge, "Invalid page type");

  // Undo page allocation
  undo_alloc_page(page);
  return true;
}

bool ZObjectAllocator::undo_alloc_medium_object(ZPage* page, uintptr_t addr, size_t size) {
  assert(page->type() == ZPageTypeMedium, "Invalid page type");

  // Try atomic undo on shared page
  return page->undo_alloc_object_atomic(addr, size);
}

bool ZObjectAllocator::undo_alloc_small_object_from_nonworker(ZPage* page, uintptr_t addr, size_t size) {
  assert(page->type() == ZPageTypeSmall, "Invalid page type");

  // Try atomic undo on shared page
  return page->undo_alloc_object_atomic(addr, size);
}

bool ZObjectAllocator::undo_alloc_small_object_from_worker(ZPage* page, uintptr_t addr, size_t size) {
  assert(page->type() == ZPageTypeSmall, "Invalid page type");
  assert(page == _worker_small_page.get(), "Invalid page");

  // Non-atomic undo on worker-local page
  const bool success = page->undo_alloc_object(addr, size);
  assert(success, "Should always succeed");
  return success;
}

bool ZObjectAllocator::undo_alloc_small_object(ZPage* page, uintptr_t addr, size_t size) {
  if (ZThread::is_worker()) {
    return undo_alloc_small_object_from_worker(page, addr, size);
  } else {
    return undo_alloc_small_object_from_nonworker(page, addr, size);
  }
}

bool ZObjectAllocator::undo_alloc_object(ZPage* page, uintptr_t addr, size_t size) {
  const uint8_t type = page->type();

  if (type == ZPageTypeSmall) {
    return undo_alloc_small_object(page, addr, size);
  } else if (type == ZPageTypeMedium) {
    return undo_alloc_medium_object(page, addr, size);
  } else {
    return undo_alloc_large_object(page);
  }
}

void ZObjectAllocator::undo_alloc_object_for_relocation(ZPage* page, uintptr_t addr, size_t size) {
  if (undo_alloc_object(page, addr, size)) {
    ZStatInc(ZCounterUndoObjectAllocationSucceeded);
  } else {
    ZStatInc(ZCounterUndoObjectAllocationFailed);
    log_trace(gc)("Failed to undo object allocation: " PTR_FORMAT ", Size: " SIZE_FORMAT ", Thread: " PTR_FORMAT " (%s)",
                  addr, size, ZThread::id(), ZThread::name());
  }
}

size_t ZObjectAllocator::used() const {
  size_t total_used = 0;
  size_t total_undone = 0;

  ZPerCPUConstIterator<size_t> iter_used(&_used);
  for (const size_t* cpu_used; iter_used.next(&cpu_used);) {
    total_used += *cpu_used;
  }

  ZPerCPUConstIterator<size_t> iter_undone(&_undone);
  for (const size_t* cpu_undone; iter_undone.next(&cpu_undone);) {
    total_undone += *cpu_undone;
  }

  return total_used - total_undone;
}

size_t ZObjectAllocator::remaining() const {
  assert(ZThread::is_java(), "Should be a Java thread");

  const ZPage* const page = Atomic::load_acquire(shared_small_page_addr());
  if (page != NULL) {
    return page->remaining();
  }

  return 0;
}

void ZObjectAllocator::retire_pages() {
  assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");

  // Reset used and undone bytes
  _used.set_all(0);
  _undone.set_all(0);

  // Reset allocation pages
  _shared_medium_page.set(NULL);
  _shared_small_page.set_all(NULL);
  _worker_small_page.set_all(NULL);
}