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//===-- sanitizer_allocator_primary64.h -------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Part of the Sanitizer Allocator.
//
//===----------------------------------------------------------------------===//
#ifndef SANITIZER_ALLOCATOR_H
#error This file must be included inside sanitizer_allocator.h
#endif
template<class SizeClassAllocator> struct SizeClassAllocator64LocalCache;
// SizeClassAllocator64 -- allocator for 64-bit address space.
// The template parameter Params is a class containing the actual parameters.
//
// Space: a portion of address space of kSpaceSize bytes starting at SpaceBeg.
// If kSpaceBeg is ~0 then SpaceBeg is chosen dynamically my mmap.
// Otherwise SpaceBeg=kSpaceBeg (fixed address).
// kSpaceSize is a power of two.
// At the beginning the entire space is mprotect-ed, then small parts of it
// are mapped on demand.
//
// Region: a part of Space dedicated to a single size class.
// There are kNumClasses Regions of equal size.
//
// UserChunk: a piece of memory returned to user.
// MetaChunk: kMetadataSize bytes of metadata associated with a UserChunk.
// FreeArray is an array free-d chunks (stored as 4-byte offsets)
//
// A Region looks like this:
// UserChunk1 ... UserChunkN <gap> MetaChunkN ... MetaChunk1 FreeArray
struct SizeClassAllocator64FlagMasks { // Bit masks.
enum {
kRandomShuffleChunks = 1,
};
};
template <class Params>
class SizeClassAllocator64 {
public:
static const uptr kSpaceBeg = Params::kSpaceBeg;
static const uptr kSpaceSize = Params::kSpaceSize;
static const uptr kMetadataSize = Params::kMetadataSize;
typedef typename Params::SizeClassMap SizeClassMap;
typedef typename Params::MapUnmapCallback MapUnmapCallback;
static const bool kRandomShuffleChunks =
Params::kFlags & SizeClassAllocator64FlagMasks::kRandomShuffleChunks;
typedef SizeClassAllocator64<Params> ThisT;
typedef SizeClassAllocator64LocalCache<ThisT> AllocatorCache;
// When we know the size class (the region base) we can represent a pointer
// as a 4-byte integer (offset from the region start shifted right by 4).
typedef u32 CompactPtrT;
static const uptr kCompactPtrScale = 4;
CompactPtrT PointerToCompactPtr(uptr base, uptr ptr) const {
return static_cast<CompactPtrT>((ptr - base) >> kCompactPtrScale);
}
uptr CompactPtrToPointer(uptr base, CompactPtrT ptr32) const {
return base + (static_cast<uptr>(ptr32) << kCompactPtrScale);
}
void Init(s32 release_to_os_interval_ms) {
uptr TotalSpaceSize = kSpaceSize + AdditionalSize();
if (kUsingConstantSpaceBeg) {
CHECK_EQ(kSpaceBeg, address_range.Init(TotalSpaceSize, AllocatorName(),
kSpaceBeg));
} else {
NonConstSpaceBeg = address_range.Init(TotalSpaceSize, AllocatorName());
CHECK_NE(NonConstSpaceBeg, ~(uptr)0);
}
SetReleaseToOSIntervalMs(release_to_os_interval_ms);
MapWithCallbackOrDie(SpaceEnd(), AdditionalSize());
}
s32 ReleaseToOSIntervalMs() const {
return atomic_load(&release_to_os_interval_ms_, memory_order_relaxed);
}
void SetReleaseToOSIntervalMs(s32 release_to_os_interval_ms) {
atomic_store(&release_to_os_interval_ms_, release_to_os_interval_ms,
memory_order_relaxed);
}
void ForceReleaseToOS() {
for (uptr class_id = 1; class_id < kNumClasses; class_id++) {
BlockingMutexLock l(&GetRegionInfo(class_id)->mutex);
MaybeReleaseToOS(class_id, true /*force*/);
}
}
static bool CanAllocate(uptr size, uptr alignment) {
return size <= SizeClassMap::kMaxSize &&
alignment <= SizeClassMap::kMaxSize;
}
NOINLINE void ReturnToAllocator(AllocatorStats *stat, uptr class_id,
const CompactPtrT *chunks, uptr n_chunks) {
RegionInfo *region = GetRegionInfo(class_id);
uptr region_beg = GetRegionBeginBySizeClass(class_id);
CompactPtrT *free_array = GetFreeArray(region_beg);
BlockingMutexLock l(&region->mutex);
uptr old_num_chunks = region->num_freed_chunks;
uptr new_num_freed_chunks = old_num_chunks + n_chunks;
// Failure to allocate free array space while releasing memory is non
// recoverable.
if (UNLIKELY(!EnsureFreeArraySpace(region, region_beg,
new_num_freed_chunks)))
DieOnFailure::OnOOM();
for (uptr i = 0; i < n_chunks; i++)
free_array[old_num_chunks + i] = chunks[i];
region->num_freed_chunks = new_num_freed_chunks;
region->stats.n_freed += n_chunks;
MaybeReleaseToOS(class_id, false /*force*/);
}
NOINLINE bool GetFromAllocator(AllocatorStats *stat, uptr class_id,
CompactPtrT *chunks, uptr n_chunks) {
RegionInfo *region = GetRegionInfo(class_id);
uptr region_beg = GetRegionBeginBySizeClass(class_id);
CompactPtrT *free_array = GetFreeArray(region_beg);
BlockingMutexLock l(&region->mutex);
if (UNLIKELY(region->num_freed_chunks < n_chunks)) {
if (UNLIKELY(!PopulateFreeArray(stat, class_id, region,
n_chunks - region->num_freed_chunks)))
return false;
CHECK_GE(region->num_freed_chunks, n_chunks);
}
region->num_freed_chunks -= n_chunks;
uptr base_idx = region->num_freed_chunks;
for (uptr i = 0; i < n_chunks; i++)
chunks[i] = free_array[base_idx + i];
region->stats.n_allocated += n_chunks;
return true;
}
bool PointerIsMine(const void *p) {
uptr P = reinterpret_cast<uptr>(p);
if (kUsingConstantSpaceBeg && (kSpaceBeg % kSpaceSize) == 0)
return P / kSpaceSize == kSpaceBeg / kSpaceSize;
return P >= SpaceBeg() && P < SpaceEnd();
}
uptr GetRegionBegin(const void *p) {
if (kUsingConstantSpaceBeg)
return reinterpret_cast<uptr>(p) & ~(kRegionSize - 1);
uptr space_beg = SpaceBeg();
return ((reinterpret_cast<uptr>(p) - space_beg) & ~(kRegionSize - 1)) +
space_beg;
}
uptr GetRegionBeginBySizeClass(uptr class_id) const {
return SpaceBeg() + kRegionSize * class_id;
}
uptr GetSizeClass(const void *p) {
if (kUsingConstantSpaceBeg && (kSpaceBeg % kSpaceSize) == 0)
return ((reinterpret_cast<uptr>(p)) / kRegionSize) % kNumClassesRounded;
return ((reinterpret_cast<uptr>(p) - SpaceBeg()) / kRegionSize) %
kNumClassesRounded;
}
void *GetBlockBegin(const void *p) {
uptr class_id = GetSizeClass(p);
uptr size = ClassIdToSize(class_id);
if (!size) return nullptr;
uptr chunk_idx = GetChunkIdx((uptr)p, size);
uptr reg_beg = GetRegionBegin(p);
uptr beg = chunk_idx * size;
uptr next_beg = beg + size;
if (class_id >= kNumClasses) return nullptr;
RegionInfo *region = GetRegionInfo(class_id);
if (region->mapped_user >= next_beg)
return reinterpret_cast<void*>(reg_beg + beg);
return nullptr;
}
uptr GetActuallyAllocatedSize(void *p) {
CHECK(PointerIsMine(p));
return ClassIdToSize(GetSizeClass(p));
}
uptr ClassID(uptr size) { return SizeClassMap::ClassID(size); }
void *GetMetaData(const void *p) {
uptr class_id = GetSizeClass(p);
uptr size = ClassIdToSize(class_id);
uptr chunk_idx = GetChunkIdx(reinterpret_cast<uptr>(p), size);
uptr region_beg = GetRegionBeginBySizeClass(class_id);
return reinterpret_cast<void *>(GetMetadataEnd(region_beg) -
(1 + chunk_idx) * kMetadataSize);
}
uptr TotalMemoryUsed() {
uptr res = 0;
for (uptr i = 0; i < kNumClasses; i++)
res += GetRegionInfo(i)->allocated_user;
return res;
}
// Test-only.
void TestOnlyUnmap() {
UnmapWithCallbackOrDie(SpaceBeg(), kSpaceSize + AdditionalSize());
}
static void FillMemoryProfile(uptr start, uptr rss, bool file, uptr *stats,
uptr stats_size) {
for (uptr class_id = 0; class_id < stats_size; class_id++)
if (stats[class_id] == start)
stats[class_id] = rss;
}
void PrintStats(uptr class_id, uptr rss) {
RegionInfo *region = GetRegionInfo(class_id);
if (region->mapped_user == 0) return;
uptr in_use = region->stats.n_allocated - region->stats.n_freed;
uptr avail_chunks = region->allocated_user / ClassIdToSize(class_id);
Printf(
"%s %02zd (%6zd): mapped: %6zdK allocs: %7zd frees: %7zd inuse: %6zd "
"num_freed_chunks %7zd avail: %6zd rss: %6zdK releases: %6zd "
"last released: %6zdK region: 0x%zx\n",
region->exhausted ? "F" : " ", class_id, ClassIdToSize(class_id),
region->mapped_user >> 10, region->stats.n_allocated,
region->stats.n_freed, in_use, region->num_freed_chunks, avail_chunks,
rss >> 10, region->rtoi.num_releases,
region->rtoi.last_released_bytes >> 10,
SpaceBeg() + kRegionSize * class_id);
}
void PrintStats() {
uptr rss_stats[kNumClasses];
for (uptr class_id = 0; class_id < kNumClasses; class_id++)
rss_stats[class_id] = SpaceBeg() + kRegionSize * class_id;
GetMemoryProfile(FillMemoryProfile, rss_stats, kNumClasses);
uptr total_mapped = 0;
uptr total_rss = 0;
uptr n_allocated = 0;
uptr n_freed = 0;
for (uptr class_id = 1; class_id < kNumClasses; class_id++) {
RegionInfo *region = GetRegionInfo(class_id);
if (region->mapped_user != 0) {
total_mapped += region->mapped_user;
total_rss += rss_stats[class_id];
}
n_allocated += region->stats.n_allocated;
n_freed += region->stats.n_freed;
}
Printf("Stats: SizeClassAllocator64: %zdM mapped (%zdM rss) in "
"%zd allocations; remains %zd\n", total_mapped >> 20,
total_rss >> 20, n_allocated, n_allocated - n_freed);
for (uptr class_id = 1; class_id < kNumClasses; class_id++)
PrintStats(class_id, rss_stats[class_id]);
}
// ForceLock() and ForceUnlock() are needed to implement Darwin malloc zone
// introspection API.
void ForceLock() {
for (uptr i = 0; i < kNumClasses; i++) {
GetRegionInfo(i)->mutex.Lock();
}
}
void ForceUnlock() {
for (int i = (int)kNumClasses - 1; i >= 0; i--) {
GetRegionInfo(i)->mutex.Unlock();
}
}
// Iterate over all existing chunks.
// The allocator must be locked when calling this function.
void ForEachChunk(ForEachChunkCallback callback, void *arg) {
for (uptr class_id = 1; class_id < kNumClasses; class_id++) {
RegionInfo *region = GetRegionInfo(class_id);
uptr chunk_size = ClassIdToSize(class_id);
uptr region_beg = SpaceBeg() + class_id * kRegionSize;
for (uptr chunk = region_beg;
chunk < region_beg + region->allocated_user;
chunk += chunk_size) {
// Too slow: CHECK_EQ((void *)chunk, GetBlockBegin((void *)chunk));
callback(chunk, arg);
}
}
}
static uptr ClassIdToSize(uptr class_id) {
return SizeClassMap::Size(class_id);
}
static uptr AdditionalSize() {
return RoundUpTo(sizeof(RegionInfo) * kNumClassesRounded,
GetPageSizeCached());
}
typedef SizeClassMap SizeClassMapT;
static const uptr kNumClasses = SizeClassMap::kNumClasses;
static const uptr kNumClassesRounded = SizeClassMap::kNumClassesRounded;
// A packed array of counters. Each counter occupies 2^n bits, enough to store
// counter's max_value. Ctor will try to allocate the required buffer via
// mapper->MapPackedCounterArrayBuffer and the caller is expected to check
// whether the initialization was successful by checking IsAllocated() result.
// For the performance sake, none of the accessors check the validity of the
// arguments, it is assumed that index is always in [0, n) range and the value
// is not incremented past max_value.
template<class MemoryMapperT>
class PackedCounterArray {
public:
PackedCounterArray(u64 num_counters, u64 max_value, MemoryMapperT *mapper)
: n(num_counters), memory_mapper(mapper) {
CHECK_GT(num_counters, 0);
CHECK_GT(max_value, 0);
constexpr u64 kMaxCounterBits = sizeof(*buffer) * 8ULL;
// Rounding counter storage size up to the power of two allows for using
// bit shifts calculating particular counter's index and offset.
uptr counter_size_bits =
RoundUpToPowerOfTwo(MostSignificantSetBitIndex(max_value) + 1);
CHECK_LE(counter_size_bits, kMaxCounterBits);
counter_size_bits_log = Log2(counter_size_bits);
counter_mask = ~0ULL >> (kMaxCounterBits - counter_size_bits);
uptr packing_ratio = kMaxCounterBits >> counter_size_bits_log;
CHECK_GT(packing_ratio, 0);
packing_ratio_log = Log2(packing_ratio);
bit_offset_mask = packing_ratio - 1;
buffer_size =
(RoundUpTo(n, 1ULL << packing_ratio_log) >> packing_ratio_log) *
sizeof(*buffer);
buffer = reinterpret_cast<u64*>(
memory_mapper->MapPackedCounterArrayBuffer(buffer_size));
}
~PackedCounterArray() {
if (buffer) {
memory_mapper->UnmapPackedCounterArrayBuffer(
reinterpret_cast<uptr>(buffer), buffer_size);
}
}
bool IsAllocated() const {
return !!buffer;
}
u64 GetCount() const {
return n;
}
uptr Get(uptr i) const {
DCHECK_LT(i, n);
uptr index = i >> packing_ratio_log;
uptr bit_offset = (i & bit_offset_mask) << counter_size_bits_log;
return (buffer[index] >> bit_offset) & counter_mask;
}
void Inc(uptr i) const {
DCHECK_LT(Get(i), counter_mask);
uptr index = i >> packing_ratio_log;
uptr bit_offset = (i & bit_offset_mask) << counter_size_bits_log;
buffer[index] += 1ULL << bit_offset;
}
void IncRange(uptr from, uptr to) const {
DCHECK_LE(from, to);
for (uptr i = from; i <= to; i++)
Inc(i);
}
private:
const u64 n;
u64 counter_size_bits_log;
u64 counter_mask;
u64 packing_ratio_log;
u64 bit_offset_mask;
MemoryMapperT* const memory_mapper;
u64 buffer_size;
u64* buffer;
};
template<class MemoryMapperT>
class FreePagesRangeTracker {
public:
explicit FreePagesRangeTracker(MemoryMapperT* mapper)
: memory_mapper(mapper),
page_size_scaled_log(Log2(GetPageSizeCached() >> kCompactPtrScale)),
in_the_range(false), current_page(0), current_range_start_page(0) {}
void NextPage(bool freed) {
if (freed) {
if (!in_the_range) {
current_range_start_page = current_page;
in_the_range = true;
}
} else {
CloseOpenedRange();
}
current_page++;
}
void Done() {
CloseOpenedRange();
}
private:
void CloseOpenedRange() {
if (in_the_range) {
memory_mapper->ReleasePageRangeToOS(
current_range_start_page << page_size_scaled_log,
current_page << page_size_scaled_log);
in_the_range = false;
}
}
MemoryMapperT* const memory_mapper;
const uptr page_size_scaled_log;
bool in_the_range;
uptr current_page;
uptr current_range_start_page;
};
// Iterates over the free_array to identify memory pages containing freed
// chunks only and returns these pages back to OS.
// allocated_pages_count is the total number of pages allocated for the
// current bucket.
template<class MemoryMapperT>
static void ReleaseFreeMemoryToOS(CompactPtrT *free_array,
uptr free_array_count, uptr chunk_size,
uptr allocated_pages_count,
MemoryMapperT *memory_mapper) {
const uptr page_size = GetPageSizeCached();
// Figure out the number of chunks per page and whether we can take a fast
// path (the number of chunks per page is the same for all pages).
uptr full_pages_chunk_count_max;
bool same_chunk_count_per_page;
if (chunk_size <= page_size && page_size % chunk_size == 0) {
// Same number of chunks per page, no cross overs.
full_pages_chunk_count_max = page_size / chunk_size;
same_chunk_count_per_page = true;
} else if (chunk_size <= page_size && page_size % chunk_size != 0 &&
chunk_size % (page_size % chunk_size) == 0) {
// Some chunks are crossing page boundaries, which means that the page
// contains one or two partial chunks, but all pages contain the same
// number of chunks.
full_pages_chunk_count_max = page_size / chunk_size + 1;
same_chunk_count_per_page = true;
} else if (chunk_size <= page_size) {
// Some chunks are crossing page boundaries, which means that the page
// contains one or two partial chunks.
full_pages_chunk_count_max = page_size / chunk_size + 2;
same_chunk_count_per_page = false;
} else if (chunk_size > page_size && chunk_size % page_size == 0) {
// One chunk covers multiple pages, no cross overs.
full_pages_chunk_count_max = 1;
same_chunk_count_per_page = true;
} else if (chunk_size > page_size) {
// One chunk covers multiple pages, Some chunks are crossing page
// boundaries. Some pages contain one chunk, some contain two.
full_pages_chunk_count_max = 2;
same_chunk_count_per_page = false;
} else {
UNREACHABLE("All chunk_size/page_size ratios must be handled.");
}
PackedCounterArray<MemoryMapperT> counters(allocated_pages_count,
full_pages_chunk_count_max,
memory_mapper);
if (!counters.IsAllocated())
return;
const uptr chunk_size_scaled = chunk_size >> kCompactPtrScale;
const uptr page_size_scaled = page_size >> kCompactPtrScale;
const uptr page_size_scaled_log = Log2(page_size_scaled);
// Iterate over free chunks and count how many free chunks affect each
// allocated page.
if (chunk_size <= page_size && page_size % chunk_size == 0) {
// Each chunk affects one page only.
for (uptr i = 0; i < free_array_count; i++)
counters.Inc(free_array[i] >> page_size_scaled_log);
} else {
// In all other cases chunks might affect more than one page.
for (uptr i = 0; i < free_array_count; i++) {
counters.IncRange(
free_array[i] >> page_size_scaled_log,
(free_array[i] + chunk_size_scaled - 1) >> page_size_scaled_log);
}
}
// Iterate over pages detecting ranges of pages with chunk counters equal
// to the expected number of chunks for the particular page.
FreePagesRangeTracker<MemoryMapperT> range_tracker(memory_mapper);
if (same_chunk_count_per_page) {
// Fast path, every page has the same number of chunks affecting it.
for (uptr i = 0; i < counters.GetCount(); i++)
range_tracker.NextPage(counters.Get(i) == full_pages_chunk_count_max);
} else {
// Show path, go through the pages keeping count how many chunks affect
// each page.
const uptr pn =
chunk_size < page_size ? page_size_scaled / chunk_size_scaled : 1;
const uptr pnc = pn * chunk_size_scaled;
// The idea is to increment the current page pointer by the first chunk
// size, middle portion size (the portion of the page covered by chunks
// except the first and the last one) and then the last chunk size, adding
// up the number of chunks on the current page and checking on every step
// whether the page boundary was crossed.
uptr prev_page_boundary = 0;
uptr current_boundary = 0;
for (uptr i = 0; i < counters.GetCount(); i++) {
uptr page_boundary = prev_page_boundary + page_size_scaled;
uptr chunks_per_page = pn;
if (current_boundary < page_boundary) {
if (current_boundary > prev_page_boundary)
chunks_per_page++;
current_boundary += pnc;
if (current_boundary < page_boundary) {
chunks_per_page++;
current_boundary += chunk_size_scaled;
}
}
prev_page_boundary = page_boundary;
range_tracker.NextPage(counters.Get(i) == chunks_per_page);
}
}
range_tracker.Done();
}
private:
friend class MemoryMapper;
ReservedAddressRange address_range;
static const char *AllocatorName() { return "sanitizer_allocator"; }
static const uptr kRegionSize = kSpaceSize / kNumClassesRounded;
// FreeArray is the array of free-d chunks (stored as 4-byte offsets).
// In the worst case it may reguire kRegionSize/SizeClassMap::kMinSize
// elements, but in reality this will not happen. For simplicity we
// dedicate 1/8 of the region's virtual space to FreeArray.
static const uptr kFreeArraySize = kRegionSize / 8;
static const bool kUsingConstantSpaceBeg = kSpaceBeg != ~(uptr)0;
uptr NonConstSpaceBeg;
uptr SpaceBeg() const {
return kUsingConstantSpaceBeg ? kSpaceBeg : NonConstSpaceBeg;
}
uptr SpaceEnd() const { return SpaceBeg() + kSpaceSize; }
// kRegionSize must be >= 2^32.
COMPILER_CHECK((kRegionSize) >= (1ULL << (SANITIZER_WORDSIZE / 2)));
// kRegionSize must be <= 2^36, see CompactPtrT.
COMPILER_CHECK((kRegionSize) <= (1ULL << (SANITIZER_WORDSIZE / 2 + 4)));
// Call mmap for user memory with at least this size.
static const uptr kUserMapSize = 1 << 16;
// Call mmap for metadata memory with at least this size.
static const uptr kMetaMapSize = 1 << 16;
// Call mmap for free array memory with at least this size.
static const uptr kFreeArrayMapSize = 1 << 16;
atomic_sint32_t release_to_os_interval_ms_;
struct Stats {
uptr n_allocated;
uptr n_freed;
};
struct ReleaseToOsInfo {
uptr n_freed_at_last_release;
uptr num_releases;
u64 last_release_at_ns;
u64 last_released_bytes;
};
struct RegionInfo {
BlockingMutex mutex;
uptr num_freed_chunks; // Number of elements in the freearray.
uptr mapped_free_array; // Bytes mapped for freearray.
uptr allocated_user; // Bytes allocated for user memory.
uptr allocated_meta; // Bytes allocated for metadata.
uptr mapped_user; // Bytes mapped for user memory.
uptr mapped_meta; // Bytes mapped for metadata.
u32 rand_state; // Seed for random shuffle, used if kRandomShuffleChunks.
bool exhausted; // Whether region is out of space for new chunks.
Stats stats;
ReleaseToOsInfo rtoi;
};
COMPILER_CHECK(sizeof(RegionInfo) >= kCacheLineSize);
RegionInfo *GetRegionInfo(uptr class_id) const {
CHECK_LT(class_id, kNumClasses);
RegionInfo *regions =
reinterpret_cast<RegionInfo *>(SpaceBeg() + kSpaceSize);
return &regions[class_id];
}
uptr GetMetadataEnd(uptr region_beg) const {
return region_beg + kRegionSize - kFreeArraySize;
}
uptr GetChunkIdx(uptr chunk, uptr size) const {
if (!kUsingConstantSpaceBeg)
chunk -= SpaceBeg();
uptr offset = chunk % kRegionSize;
// Here we divide by a non-constant. This is costly.
// size always fits into 32-bits. If the offset fits too, use 32-bit div.
if (offset >> (SANITIZER_WORDSIZE / 2))
return offset / size;
return (u32)offset / (u32)size;
}
CompactPtrT *GetFreeArray(uptr region_beg) const {
return reinterpret_cast<CompactPtrT *>(GetMetadataEnd(region_beg));
}
bool MapWithCallback(uptr beg, uptr size) {
uptr mapped = address_range.Map(beg, size);
if (UNLIKELY(!mapped))
return false;
CHECK_EQ(beg, mapped);
MapUnmapCallback().OnMap(beg, size);
return true;
}
void MapWithCallbackOrDie(uptr beg, uptr size) {
CHECK_EQ(beg, address_range.MapOrDie(beg, size));
MapUnmapCallback().OnMap(beg, size);
}
void UnmapWithCallbackOrDie(uptr beg, uptr size) {
MapUnmapCallback().OnUnmap(beg, size);
address_range.Unmap(beg, size);
}
bool EnsureFreeArraySpace(RegionInfo *region, uptr region_beg,
uptr num_freed_chunks) {
uptr needed_space = num_freed_chunks * sizeof(CompactPtrT);
if (region->mapped_free_array < needed_space) {
uptr new_mapped_free_array = RoundUpTo(needed_space, kFreeArrayMapSize);
CHECK_LE(new_mapped_free_array, kFreeArraySize);
uptr current_map_end = reinterpret_cast<uptr>(GetFreeArray(region_beg)) +
region->mapped_free_array;
uptr new_map_size = new_mapped_free_array - region->mapped_free_array;
if (UNLIKELY(!MapWithCallback(current_map_end, new_map_size)))
return false;
region->mapped_free_array = new_mapped_free_array;
}
return true;
}
// Check whether this size class is exhausted.
bool IsRegionExhausted(RegionInfo *region, uptr class_id,
uptr additional_map_size) {
if (LIKELY(region->mapped_user + region->mapped_meta +
additional_map_size <= kRegionSize - kFreeArraySize))
return false;
if (!region->exhausted) {
region->exhausted = true;
Printf("%s: Out of memory. ", SanitizerToolName);
Printf("The process has exhausted %zuMB for size class %zu.\n",
kRegionSize >> 20, ClassIdToSize(class_id));
}
return true;
}
NOINLINE bool PopulateFreeArray(AllocatorStats *stat, uptr class_id,
RegionInfo *region, uptr requested_count) {
// region->mutex is held.
const uptr region_beg = GetRegionBeginBySizeClass(class_id);
const uptr size = ClassIdToSize(class_id);
const uptr total_user_bytes =
region->allocated_user + requested_count * size;
// Map more space for chunks, if necessary.
if (LIKELY(total_user_bytes > region->mapped_user)) {
if (UNLIKELY(region->mapped_user == 0)) {
if (!kUsingConstantSpaceBeg && kRandomShuffleChunks)
// The random state is initialized from ASLR.
region->rand_state = static_cast<u32>(region_beg >> 12);
// Postpone the first release to OS attempt for ReleaseToOSIntervalMs,
// preventing just allocated memory from being released sooner than
// necessary and also preventing extraneous ReleaseMemoryPagesToOS calls
// for short lived processes.
// Do it only when the feature is turned on, to avoid a potentially
// extraneous syscall.
if (ReleaseToOSIntervalMs() >= 0)
region->rtoi.last_release_at_ns = MonotonicNanoTime();
}
// Do the mmap for the user memory.
const uptr user_map_size =
RoundUpTo(total_user_bytes - region->mapped_user, kUserMapSize);
if (UNLIKELY(IsRegionExhausted(region, class_id, user_map_size)))
return false;
if (UNLIKELY(!MapWithCallback(region_beg + region->mapped_user,
user_map_size)))
return false;
stat->Add(AllocatorStatMapped, user_map_size);
region->mapped_user += user_map_size;
}
const uptr new_chunks_count =
(region->mapped_user - region->allocated_user) / size;
if (kMetadataSize) {
// Calculate the required space for metadata.
const uptr total_meta_bytes =
region->allocated_meta + new_chunks_count * kMetadataSize;
const uptr meta_map_size = (total_meta_bytes > region->mapped_meta) ?
RoundUpTo(total_meta_bytes - region->mapped_meta, kMetaMapSize) : 0;
// Map more space for metadata, if necessary.
if (meta_map_size) {
if (UNLIKELY(IsRegionExhausted(region, class_id, meta_map_size)))
return false;
if (UNLIKELY(!MapWithCallback(
GetMetadataEnd(region_beg) - region->mapped_meta - meta_map_size,
meta_map_size)))
return false;
region->mapped_meta += meta_map_size;
}
}
// If necessary, allocate more space for the free array and populate it with
// newly allocated chunks.
const uptr total_freed_chunks = region->num_freed_chunks + new_chunks_count;
if (UNLIKELY(!EnsureFreeArraySpace(region, region_beg, total_freed_chunks)))
return false;
CompactPtrT *free_array = GetFreeArray(region_beg);
for (uptr i = 0, chunk = region->allocated_user; i < new_chunks_count;
i++, chunk += size)
free_array[total_freed_chunks - 1 - i] = PointerToCompactPtr(0, chunk);
if (kRandomShuffleChunks)
RandomShuffle(&free_array[region->num_freed_chunks], new_chunks_count,
&region->rand_state);
// All necessary memory is mapped and now it is safe to advance all
// 'allocated_*' counters.
region->num_freed_chunks += new_chunks_count;
region->allocated_user += new_chunks_count * size;
CHECK_LE(region->allocated_user, region->mapped_user);
region->allocated_meta += new_chunks_count * kMetadataSize;
CHECK_LE(region->allocated_meta, region->mapped_meta);
region->exhausted = false;
// TODO(alekseyshl): Consider bumping last_release_at_ns here to prevent
// MaybeReleaseToOS from releasing just allocated pages or protect these
// not yet used chunks some other way.
return true;
}
class MemoryMapper {
public:
MemoryMapper(const ThisT& base_allocator, uptr class_id)
: allocator(base_allocator),
region_base(base_allocator.GetRegionBeginBySizeClass(class_id)),
released_ranges_count(0),
released_bytes(0) {
}
uptr GetReleasedRangesCount() const {
return released_ranges_count;
}
uptr GetReleasedBytes() const {
return released_bytes;
}
uptr MapPackedCounterArrayBuffer(uptr buffer_size) {
// TODO(alekseyshl): The idea to explore is to check if we have enough
// space between num_freed_chunks*sizeof(CompactPtrT) and
// mapped_free_array to fit buffer_size bytes and use that space instead
// of mapping a temporary one.
return reinterpret_cast<uptr>(
MmapOrDieOnFatalError(buffer_size, "ReleaseToOSPageCounters"));
}
void UnmapPackedCounterArrayBuffer(uptr buffer, uptr buffer_size) {
UnmapOrDie(reinterpret_cast<void *>(buffer), buffer_size);
}
// Releases [from, to) range of pages back to OS.
void ReleasePageRangeToOS(CompactPtrT from, CompactPtrT to) {
const uptr from_page = allocator.CompactPtrToPointer(region_base, from);
const uptr to_page = allocator.CompactPtrToPointer(region_base, to);
ReleaseMemoryPagesToOS(from_page, to_page);
released_ranges_count++;
released_bytes += to_page - from_page;
}
private:
const ThisT& allocator;
const uptr region_base;
uptr released_ranges_count;
uptr released_bytes;
};
// Attempts to release RAM occupied by freed chunks back to OS. The region is
// expected to be locked.
void MaybeReleaseToOS(uptr class_id, bool force) {
RegionInfo *region = GetRegionInfo(class_id);
const uptr chunk_size = ClassIdToSize(class_id);
const uptr page_size = GetPageSizeCached();
uptr n = region->num_freed_chunks;
if (n * chunk_size < page_size)
return; // No chance to release anything.
if ((region->stats.n_freed -
region->rtoi.n_freed_at_last_release) * chunk_size < page_size) {
return; // Nothing new to release.
}
if (!force) {
s32 interval_ms = ReleaseToOSIntervalMs();
if (interval_ms < 0)
return;
if (region->rtoi.last_release_at_ns + interval_ms * 1000000ULL >
MonotonicNanoTime()) {
return; // Memory was returned recently.
}
}
MemoryMapper memory_mapper(*this, class_id);
ReleaseFreeMemoryToOS<MemoryMapper>(
GetFreeArray(GetRegionBeginBySizeClass(class_id)), n, chunk_size,
RoundUpTo(region->allocated_user, page_size) / page_size,
&memory_mapper);
if (memory_mapper.GetReleasedRangesCount() > 0) {
region->rtoi.n_freed_at_last_release = region->stats.n_freed;
region->rtoi.num_releases += memory_mapper.GetReleasedRangesCount();
region->rtoi.last_released_bytes = memory_mapper.GetReleasedBytes();
}
region->rtoi.last_release_at_ns = MonotonicNanoTime();
}
};
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