content/common/host_discardable_shared_memory_manager.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/common/host_discardable_shared_memory_manager.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/atomic_sequence_num.h"
  10 #include "base/bind.h"
  11 #include "base/callback.h"
  12 #include "base/debug/crash_logging.h"
  13 #include "base/lazy_instance.h"
  14 #include "base/memory/discardable_memory.h"
  15 #include "base/numerics/safe_math.h"
  16 #include "base/strings/string_number_conversions.h"
  17 #include "base/strings/stringprintf.h"
  18 #include "base/sys_info.h"
  19 #include "base/thread_task_runner_handle.h"
  20 #include "base/trace_event/memory_allocator_dump.h"
  21 #include "base/trace_event/memory_dump_manager.h"
  22 #include "base/trace_event/process_memory_dump.h"
  23 #include "base/trace_event/trace_event.h"
  24 #include "content/common/child_process_host_impl.h"
  25 #include "content/common/discardable_shared_memory_heap.h"
  26 #include "content/public/common/child_process_host.h"
  27
  28 namespace content {
  29 namespace {
  30
  31 class DiscardableMemoryImpl : public base::DiscardableMemory {
  32  public:
  33   DiscardableMemoryImpl(scoped_ptr<base::DiscardableSharedMemory> shared_memory,
  34                         const base::Closure& deleted_callback)
  35       : shared_memory_(shared_memory.Pass()),
  36         deleted_callback_(deleted_callback),
  37         is_locked_(true) {}
  38
  39   ~DiscardableMemoryImpl() override {
  40     if (is_locked_)
  41       shared_memory_->Unlock(0, 0);
  42
  43     deleted_callback_.Run();
  44   }
  45
  46   // Overridden from base::DiscardableMemory:
  47   bool Lock() override {
  48     DCHECK(!is_locked_);
  49
  50     if (shared_memory_->Lock(0, 0) != base::DiscardableSharedMemory::SUCCESS)
  51       return false;
  52
  53     is_locked_ = true;
  54     return true;
  55   }
  56   void Unlock() override {
  57     DCHECK(is_locked_);
  58
  59     shared_memory_->Unlock(0, 0);
  60     is_locked_ = false;
  61   }
  62   void* data() const override {
  63     DCHECK(is_locked_);
  64     return shared_memory_->memory();
  65   }
  66
  67  private:
  68   scoped_ptr<base::DiscardableSharedMemory> shared_memory_;
  69   const base::Closure deleted_callback_;
  70   bool is_locked_;
  71
  72   DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryImpl);
  73 };
  74
  75 base::LazyInstance<HostDiscardableSharedMemoryManager>
  76     g_discardable_shared_memory_manager = LAZY_INSTANCE_INITIALIZER;
  77
  78 #if defined(OS_ANDROID)
  79 // Limits the number of FDs used to 32, assuming a 4MB allocation size.
  80 const int64_t kMaxDefaultMemoryLimit = 128 * 1024 * 1024;
  81 #else
  82 const int64_t kMaxDefaultMemoryLimit = 512 * 1024 * 1024;
  83 #endif
  84
  85 const int kEnforceMemoryPolicyDelayMs = 1000;
  86
  87 // Global atomic to generate unique discardable shared memory IDs.
  88 base::StaticAtomicSequenceNumber g_next_discardable_shared_memory_id;
  89
  90 }  // namespace
  91
  92 HostDiscardableSharedMemoryManager::MemorySegment::MemorySegment(
  93     scoped_ptr<base::DiscardableSharedMemory> memory)
  94     : memory_(memory.Pass()) {
  95 }
  96
  97 HostDiscardableSharedMemoryManager::MemorySegment::~MemorySegment() {
  98 }
  99
 100 HostDiscardableSharedMemoryManager::HostDiscardableSharedMemoryManager()
 101     : memory_limit_(
 102           // Allow 25% of physical memory to be used for discardable memory.
 103           std::min(base::SysInfo::AmountOfPhysicalMemory() / 4,
 104                    base::SysInfo::IsLowEndDevice()
 105                        ?
 106                        // Use 1/8th of discardable memory on low-end devices.
 107                        kMaxDefaultMemoryLimit / 8
 108                        : kMaxDefaultMemoryLimit)),
 109       bytes_allocated_(0),
 110       memory_pressure_listener_(new base::MemoryPressureListener(
 111           base::Bind(&HostDiscardableSharedMemoryManager::OnMemoryPressure,
 112                      base::Unretained(this)))),
 113       enforce_memory_policy_pending_(false),
 114       weak_ptr_factory_(this) {
 115   DCHECK_NE(memory_limit_, 0u);
 116   base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
 117       this);
 118 }
 119
 120 HostDiscardableSharedMemoryManager::~HostDiscardableSharedMemoryManager() {
 121   base::trace_event::MemoryDumpManager::GetInstance()->UnregisterDumpProvider(
 122       this);
 123 }
 124
 125 HostDiscardableSharedMemoryManager*
 126 HostDiscardableSharedMemoryManager::current() {
 127   return g_discardable_shared_memory_manager.Pointer();
 128 }
 129
 130 scoped_ptr<base::DiscardableMemory>
 131 HostDiscardableSharedMemoryManager::AllocateLockedDiscardableMemory(
 132     size_t size) {
 133   DiscardableSharedMemoryId new_id =
 134       g_next_discardable_shared_memory_id.GetNext();
 135   base::ProcessHandle current_process_handle = base::GetCurrentProcessHandle();
 136
 137   // Note: Use DiscardableSharedMemoryHeap for in-process allocation
 138   // of discardable memory if the cost of each allocation is too high.
 139   base::SharedMemoryHandle handle;
 140   AllocateLockedDiscardableSharedMemory(current_process_handle,
 141                                         ChildProcessHost::kInvalidUniqueID,
 142                                         size, new_id, &handle);
 143   CHECK(base::SharedMemory::IsHandleValid(handle));
 144   scoped_ptr<base::DiscardableSharedMemory> memory(
 145       new base::DiscardableSharedMemory(handle));
 146   CHECK(memory->Map(size));
 147   // Close file descriptor to avoid running out.
 148   memory->Close();
 149   return make_scoped_ptr(new DiscardableMemoryImpl(
 150       memory.Pass(),
 151       base::Bind(
 152           &HostDiscardableSharedMemoryManager::DeletedDiscardableSharedMemory,
 153           base::Unretained(this), new_id, ChildProcessHost::kInvalidUniqueID)));
 154 }
 155
 156 bool HostDiscardableSharedMemoryManager::OnMemoryDump(
 157     base::trace_event::ProcessMemoryDump* pmd) {
 158   base::AutoLock lock(lock_);
 159   for (const auto& process_entry : processes_) {
 160     const int child_process_id = process_entry.first;
 161     const MemorySegmentMap& process_segments = process_entry.second;
 162     for (const auto& segment_entry : process_segments) {
 163       const int segment_id = segment_entry.first;
 164       const MemorySegment* segment = segment_entry.second.get();
 165       std::string dump_name = base::StringPrintf(
 166           "discardable/process_%x/segment_%d", child_process_id, segment_id);
 167       base::trace_event::MemoryAllocatorDump* dump =
 168           pmd->CreateAllocatorDump(dump_name);
 169       dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
 170                       base::trace_event::MemoryAllocatorDump::kUnitsBytes,
 171                       segment->memory()->mapped_size());
 172
 173       // Create the cross-process ownership edge. If the child creates a
 174       // corresponding dump for the same segment, this will avoid to
 175       // double-count them in tracing. If, instead, no other process will emit a
 176       // dump with the same guid, the segment will be accounted to the browser.
 177       const uint64 child_tracing_process_id =
 178           ChildProcessHostImpl::ChildProcessUniqueIdToTracingProcessId(
 179               child_process_id);
 180       base::trace_event::MemoryAllocatorDumpGuid shared_segment_guid =
 181           DiscardableSharedMemoryHeap::GetSegmentGUIDForTracing(
 182               child_tracing_process_id, segment_id);
 183       pmd->CreateSharedGlobalAllocatorDump(shared_segment_guid);
 184       pmd->AddOwnershipEdge(dump->guid(), shared_segment_guid);
 185     }
 186   }
 187   return true;
 188 }
 189
 190 void HostDiscardableSharedMemoryManager::
 191     AllocateLockedDiscardableSharedMemoryForChild(
 192         base::ProcessHandle process_handle,
 193         int child_process_id,
 194         size_t size,
 195         DiscardableSharedMemoryId id,
 196         base::SharedMemoryHandle* shared_memory_handle) {
 197   AllocateLockedDiscardableSharedMemory(process_handle, child_process_id, size,
 198                                         id, shared_memory_handle);
 199 }
 200
 201 void HostDiscardableSharedMemoryManager::ChildDeletedDiscardableSharedMemory(
 202     DiscardableSharedMemoryId id,
 203     int child_process_id) {
 204   DeletedDiscardableSharedMemory(id, child_process_id);
 205 }
 206
 207 void HostDiscardableSharedMemoryManager::ProcessRemoved(int child_process_id) {
 208   base::AutoLock lock(lock_);
 209
 210   ProcessMap::iterator process_it = processes_.find(child_process_id);
 211   if (process_it == processes_.end())
 212     return;
 213
 214   size_t bytes_allocated_before_releasing_memory = bytes_allocated_;
 215
 216   for (auto& segment_it : process_it->second)
 217     ReleaseMemory(segment_it.second->memory());
 218
 219   processes_.erase(process_it);
 220
 221   if (bytes_allocated_ != bytes_allocated_before_releasing_memory)
 222     BytesAllocatedChanged(bytes_allocated_);
 223 }
 224
 225 void HostDiscardableSharedMemoryManager::SetMemoryLimit(size_t limit) {
 226   base::AutoLock lock(lock_);
 227
 228   memory_limit_ = limit;
 229   ReduceMemoryUsageUntilWithinMemoryLimit();
 230 }
 231
 232 void HostDiscardableSharedMemoryManager::EnforceMemoryPolicy() {
 233   base::AutoLock lock(lock_);
 234
 235   enforce_memory_policy_pending_ = false;
 236   ReduceMemoryUsageUntilWithinMemoryLimit();
 237 }
 238
 239 size_t HostDiscardableSharedMemoryManager::GetBytesAllocated() {
 240   base::AutoLock lock(lock_);
 241
 242   return bytes_allocated_;
 243 }
 244
 245 void HostDiscardableSharedMemoryManager::AllocateLockedDiscardableSharedMemory(
 246     base::ProcessHandle process_handle,
 247     int client_process_id,
 248     size_t size,
 249     DiscardableSharedMemoryId id,
 250     base::SharedMemoryHandle* shared_memory_handle) {
 251   base::AutoLock lock(lock_);
 252
 253   // Make sure |id| is not already in use.
 254   MemorySegmentMap& process_segments = processes_[client_process_id];
 255   if (process_segments.find(id) != process_segments.end()) {
 256     LOG(ERROR) << "Invalid discardable shared memory ID";
 257     *shared_memory_handle = base::SharedMemory::NULLHandle();
 258     return;
 259   }
 260
 261   // Memory usage must be reduced to prevent the addition of |size| from
 262   // taking usage above the limit. Usage should be reduced to 0 in cases
 263   // where |size| is greater than the limit.
 264   size_t limit = 0;
 265   // Note: the actual mapped size can be larger than requested and cause
 266   // |bytes_allocated_| to temporarily be larger than |memory_limit_|. The
 267   // error is minimized by incrementing |bytes_allocated_| with the actual
 268   // mapped size rather than |size| below.
 269   if (size < memory_limit_)
 270     limit = memory_limit_ - size;
 271
 272   if (bytes_allocated_ > limit)
 273     ReduceMemoryUsageUntilWithinLimit(limit);
 274
 275   scoped_ptr<base::DiscardableSharedMemory> memory(
 276       new base::DiscardableSharedMemory);
 277   if (!memory->CreateAndMap(size)) {
 278     *shared_memory_handle = base::SharedMemory::NULLHandle();
 279     return;
 280   }
 281
 282   if (!memory->ShareToProcess(process_handle, shared_memory_handle)) {
 283     LOG(ERROR) << "Cannot share discardable memory segment";
 284     *shared_memory_handle = base::SharedMemory::NULLHandle();
 285     return;
 286   }
 287
 288   base::CheckedNumeric<size_t> checked_bytes_allocated = bytes_allocated_;
 289   checked_bytes_allocated += memory->mapped_size();
 290   if (!checked_bytes_allocated.IsValid()) {
 291     *shared_memory_handle = base::SharedMemory::NULLHandle();
 292     return;
 293   }
 294
 295   bytes_allocated_ = checked_bytes_allocated.ValueOrDie();
 296   BytesAllocatedChanged(bytes_allocated_);
 297
 298 #if !defined(DISCARDABLE_SHARED_MEMORY_SHRINKING)
 299   // Close file descriptor to avoid running out.
 300   memory->Close();
 301 #endif
 302
 303   scoped_refptr<MemorySegment> segment(new MemorySegment(memory.Pass()));
 304   process_segments[id] = segment.get();
 305   segments_.push_back(segment.get());
 306   std::push_heap(segments_.begin(), segments_.end(), CompareMemoryUsageTime);
 307
 308   if (bytes_allocated_ > memory_limit_)
 309     ScheduleEnforceMemoryPolicy();
 310 }
 311
 312 void HostDiscardableSharedMemoryManager::DeletedDiscardableSharedMemory(
 313     DiscardableSharedMemoryId id,
 314     int client_process_id) {
 315   base::AutoLock lock(lock_);
 316
 317   MemorySegmentMap& process_segments = processes_[client_process_id];
 318
 319   MemorySegmentMap::iterator segment_it = process_segments.find(id);
 320   if (segment_it == process_segments.end()) {
 321     LOG(ERROR) << "Invalid discardable shared memory ID";
 322     return;
 323   }
 324
 325   size_t bytes_allocated_before_releasing_memory = bytes_allocated_;
 326
 327   ReleaseMemory(segment_it->second->memory());
 328
 329   process_segments.erase(segment_it);
 330
 331   if (bytes_allocated_ != bytes_allocated_before_releasing_memory)
 332     BytesAllocatedChanged(bytes_allocated_);
 333 }
 334
 335 void HostDiscardableSharedMemoryManager::OnMemoryPressure(
 336     base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
 337   base::AutoLock lock(lock_);
 338
 339   switch (memory_pressure_level) {
 340     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE:
 341       break;
 342     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE:
 343       // Purge memory until usage is within half of |memory_limit_|.
 344       ReduceMemoryUsageUntilWithinLimit(memory_limit_ / 2);
 345       break;
 346     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL:
 347       // Purge everything possible when pressure is critical.
 348       ReduceMemoryUsageUntilWithinLimit(0);
 349       break;
 350   }
 351 }
 352
 353 void
 354 HostDiscardableSharedMemoryManager::ReduceMemoryUsageUntilWithinMemoryLimit() {
 355   lock_.AssertAcquired();
 356
 357   if (bytes_allocated_ <= memory_limit_)
 358     return;
 359
 360   ReduceMemoryUsageUntilWithinLimit(memory_limit_);
 361   if (bytes_allocated_ > memory_limit_)
 362     ScheduleEnforceMemoryPolicy();
 363 }
 364
 365 void HostDiscardableSharedMemoryManager::ReduceMemoryUsageUntilWithinLimit(
 366     size_t limit) {
 367   TRACE_EVENT1("renderer_host",
 368                "HostDiscardableSharedMemoryManager::"
 369                "ReduceMemoryUsageUntilWithinLimit",
 370                "bytes_allocated",
 371                bytes_allocated_);
 372
 373   // Usage time of currently locked segments are updated to this time and
 374   // we stop eviction attempts as soon as we come across a segment that we've
 375   // previously tried to evict but was locked.
 376   base::Time current_time = Now();
 377
 378   lock_.AssertAcquired();
 379   size_t bytes_allocated_before_purging = bytes_allocated_;
 380   while (!segments_.empty()) {
 381     if (bytes_allocated_ <= limit)
 382       break;
 383
 384     // Stop eviction attempts when the LRU segment is currently in use.
 385     if (segments_.front()->memory()->last_known_usage() >= current_time)
 386       break;
 387
 388     std::pop_heap(segments_.begin(), segments_.end(), CompareMemoryUsageTime);
 389     scoped_refptr<MemorySegment> segment = segments_.back();
 390     segments_.pop_back();
 391
 392     // Attempt to purge LRU segment. When successful, released the memory.
 393     if (segment->memory()->Purge(current_time)) {
 394 #if defined(DISCARDABLE_SHARED_MEMORY_SHRINKING)
 395       size_t size = segment->memory()->mapped_size();
 396       DCHECK_GE(bytes_allocated_, size);
 397       bytes_allocated_ -= size;
 398       // Shrink memory segment. This will immediately release the memory to
 399       // the OS.
 400       segment->memory()->Shrink();
 401       DCHECK_EQ(segment->memory()->mapped_size(), 0u);
 402 #endif
 403       ReleaseMemory(segment->memory());
 404       continue;
 405     }
 406
 407     // Add memory segment (with updated usage timestamp) back on heap after
 408     // failed attempt to purge it.
 409     segments_.push_back(segment.get());
 410     std::push_heap(segments_.begin(), segments_.end(), CompareMemoryUsageTime);
 411   }
 412
 413   if (bytes_allocated_ != bytes_allocated_before_purging)
 414     BytesAllocatedChanged(bytes_allocated_);
 415 }
 416
 417 void HostDiscardableSharedMemoryManager::ReleaseMemory(
 418     base::DiscardableSharedMemory* memory) {
 419   lock_.AssertAcquired();
 420
 421   size_t size = memory->mapped_size();
 422   DCHECK_GE(bytes_allocated_, size);
 423   bytes_allocated_ -= size;
 424
 425   // This will unmap the memory segment and drop our reference. The result
 426   // is that the memory will be released to the OS if the child process is
 427   // no longer referencing it.
 428   // Note: We intentionally leave the segment in the |segments| vector to
 429   // avoid reconstructing the heap. The element will be removed from the heap
 430   // when its last usage time is older than all other segments.
 431   memory->Unmap();
 432   memory->Close();
 433 }
 434
 435 void HostDiscardableSharedMemoryManager::BytesAllocatedChanged(
 436     size_t new_bytes_allocated) const {
 437   TRACE_COUNTER1("renderer_host", "TotalDiscardableMemoryUsage",
 438                  new_bytes_allocated);
 439
 440   static const char kTotalDiscardableMemoryAllocatedKey[] =
 441       "total-discardable-memory-allocated";
 442   base::debug::SetCrashKeyValue(kTotalDiscardableMemoryAllocatedKey,
 443                                 base::Uint64ToString(new_bytes_allocated));
 444 }
 445
 446 base::Time HostDiscardableSharedMemoryManager::Now() const {
 447   return base::Time::Now();
 448 }
 449
 450 void HostDiscardableSharedMemoryManager::ScheduleEnforceMemoryPolicy() {
 451   lock_.AssertAcquired();
 452
 453   if (enforce_memory_policy_pending_)
 454     return;
 455
 456   enforce_memory_policy_pending_ = true;
 457   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
 458       FROM_HERE,
 459       base::Bind(&HostDiscardableSharedMemoryManager::EnforceMemoryPolicy,
 460                  weak_ptr_factory_.GetWeakPtr()),
 461       base::TimeDelta::FromMilliseconds(kEnforceMemoryPolicyDelayMs));
 462 }
 463
 464 }  // namespace content