| // Copyright (c) 2008, Google Inc. |
| // All rights reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following disclaimer |
| // in the documentation and/or other materials provided with the |
| // distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived from |
| // this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| // --- |
| // Author: Sanjay Ghemawat <opensource@google.com> |
| |
| #include "config.h" |
| #include "common.h" |
| #include "system-alloc.h" |
| #include "base/commandlineflags.h" |
| |
| namespace tcmalloc { |
| |
| // Define the maximum number of object per classe type to transfer between |
| // thread and central caches. Default is 32. |
| static int32 FLAGS_tcmalloc_transfer_num_objects; |
| |
| static const int32 kDefaultTransferNumObjecs = 32768; |
| |
| // The init function is provided to explicit initialize the variable value |
| // from the env. var to avoid C++ global construction that might defer its |
| // initialization after a malloc/new call. |
| static inline void InitTCMallocTransferNumObjects() |
| { |
| if (UNLIKELY(FLAGS_tcmalloc_transfer_num_objects == 0)) { |
| const char *envval = getenv("TCMALLOC_TRANSFER_NUM_OBJ"); |
| FLAGS_tcmalloc_transfer_num_objects = !envval ? kDefaultTransferNumObjecs : |
| strtol(envval, NULL, 10); |
| } |
| } |
| |
| // Note: the following only works for "n"s that fit in 32-bits, but |
| // that is fine since we only use it for small sizes. |
| static inline int LgFloor(size_t n) { |
| int log = 0; |
| for (int i = 4; i >= 0; --i) { |
| int shift = (1 << i); |
| size_t x = n >> shift; |
| if (x != 0) { |
| n = x; |
| log += shift; |
| } |
| } |
| ASSERT(n == 1); |
| return log; |
| } |
| |
| int AlignmentForSize(size_t size) { |
| int alignment = kAlignment; |
| if (size > kMaxSize) { |
| // Cap alignment at kPageSize for large sizes. |
| alignment = kPageSize; |
| } else if (size >= 128) { |
| // Space wasted due to alignment is at most 1/8, i.e., 12.5%. |
| alignment = (1 << LgFloor(size)) / 8; |
| } else if (size >= kMinAlign) { |
| // We need an alignment of at least 16 bytes to satisfy |
| // requirements for some SSE types. |
| alignment = kMinAlign; |
| } |
| // Maximum alignment allowed is page size alignment. |
| if (alignment > kPageSize) { |
| alignment = kPageSize; |
| } |
| CHECK_CONDITION(size < kMinAlign || alignment >= kMinAlign); |
| CHECK_CONDITION((alignment & (alignment - 1)) == 0); |
| return alignment; |
| } |
| |
| int SizeMap::NumMoveSize(size_t size) { |
| if (size == 0) return 0; |
| // Use approx 64k transfers between thread and central caches. |
| int num = static_cast<int>(64.0 * 1024.0 / size); |
| if (num < 2) num = 2; |
| |
| // Avoid bringing too many objects into small object free lists. |
| // If this value is too large: |
| // - We waste memory with extra objects sitting in the thread caches. |
| // - The central freelist holds its lock for too long while |
| // building a linked list of objects, slowing down the allocations |
| // of other threads. |
| // If this value is too small: |
| // - We go to the central freelist too often and we have to acquire |
| // its lock each time. |
| // This value strikes a balance between the constraints above. |
| if (num > FLAGS_tcmalloc_transfer_num_objects) |
| num = FLAGS_tcmalloc_transfer_num_objects; |
| |
| return num; |
| } |
| |
| // Initialize the mapping arrays |
| void SizeMap::Init() { |
| InitTCMallocTransferNumObjects(); |
| |
| // Do some sanity checking on add_amount[]/shift_amount[]/class_array[] |
| if (ClassIndex(0) < 0) { |
| Log(kCrash, __FILE__, __LINE__, |
| "Invalid class index for size 0", ClassIndex(0)); |
| } |
| if (ClassIndex(kMaxSize) >= sizeof(class_array_)) { |
| Log(kCrash, __FILE__, __LINE__, |
| "Invalid class index for kMaxSize", ClassIndex(kMaxSize)); |
| } |
| |
| // Compute the size classes we want to use |
| int sc = 1; // Next size class to assign |
| int alignment = kAlignment; |
| CHECK_CONDITION(kAlignment <= kMinAlign); |
| for (size_t size = kAlignment; size <= kMaxSize; size += alignment) { |
| alignment = AlignmentForSize(size); |
| CHECK_CONDITION((size % alignment) == 0); |
| |
| int blocks_to_move = NumMoveSize(size) / 4; |
| size_t psize = 0; |
| do { |
| psize += kPageSize; |
| // Allocate enough pages so leftover is less than 1/8 of total. |
| // This bounds wasted space to at most 12.5%. |
| while ((psize % size) > (psize >> 3)) { |
| psize += kPageSize; |
| } |
| // Continue to add pages until there are at least as many objects in |
| // the span as are needed when moving objects from the central |
| // freelists and spans to the thread caches. |
| } while ((psize / size) < (blocks_to_move)); |
| const size_t my_pages = psize >> kPageShift; |
| |
| if (sc > 1 && my_pages == class_to_pages_[sc-1]) { |
| // See if we can merge this into the previous class without |
| // increasing the fragmentation of the previous class. |
| const size_t my_objects = (my_pages << kPageShift) / size; |
| const size_t prev_objects = (class_to_pages_[sc-1] << kPageShift) |
| / class_to_size_[sc-1]; |
| if (my_objects == prev_objects) { |
| // Adjust last class to include this size |
| class_to_size_[sc-1] = size; |
| continue; |
| } |
| } |
| |
| // Add new class |
| class_to_pages_[sc] = my_pages; |
| class_to_size_[sc] = size; |
| sc++; |
| } |
| if (sc != kNumClasses) { |
| Log(kCrash, __FILE__, __LINE__, |
| "wrong number of size classes: (found vs. expected )", sc, kNumClasses); |
| } |
| |
| // Initialize the mapping arrays |
| int next_size = 0; |
| for (int c = 1; c < kNumClasses; c++) { |
| const int max_size_in_class = class_to_size_[c]; |
| for (int s = next_size; s <= max_size_in_class; s += kAlignment) { |
| class_array_[ClassIndex(s)] = c; |
| } |
| next_size = max_size_in_class + kAlignment; |
| } |
| |
| // Double-check sizes just to be safe |
| for (size_t size = 0; size <= kMaxSize; size++) { |
| const int sc = SizeClass(size); |
| if (sc <= 0 || sc >= kNumClasses) { |
| Log(kCrash, __FILE__, __LINE__, |
| "Bad size class (class, size)", sc, size); |
| } |
| if (sc > 1 && size <= class_to_size_[sc-1]) { |
| Log(kCrash, __FILE__, __LINE__, |
| "Allocating unnecessarily large class (class, size)", sc, size); |
| } |
| const size_t s = class_to_size_[sc]; |
| if (size > s || s == 0) { |
| Log(kCrash, __FILE__, __LINE__, |
| "Bad (class, size, requested)", sc, s, size); |
| } |
| } |
| |
| // Initialize the num_objects_to_move array. |
| for (size_t cl = 1; cl < kNumClasses; ++cl) { |
| num_objects_to_move_[cl] = NumMoveSize(ByteSizeForClass(cl)); |
| } |
| } |
| |
| // Metadata allocator -- keeps stats about how many bytes allocated. |
| static uint64_t metadata_system_bytes_ = 0; |
| void* MetaDataAlloc(size_t bytes) { |
| void* result = TCMalloc_SystemAlloc(bytes, NULL); |
| if (result != NULL) { |
| metadata_system_bytes_ += bytes; |
| } |
| return result; |
| } |
| |
| uint64_t metadata_system_bytes() { return metadata_system_bytes_; } |
| |
| } // namespace tcmalloc |