1 /* 2 * Copyright (C) 2018 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include "src/traced/probes/ftrace/page_pool.h" 18 19 #include <array> 20 21 namespace perfetto { 22 23 namespace { 24 constexpr size_t kMaxFreelistBlocks = 128; // 128 * 32 * 4KB = 16MB. 25 } 26 27 void PagePool::NewPageBlock() { 28 std::lock_guard<std::mutex> lock(mutex_); 29 if (freelist_.empty()) { 30 write_queue_.emplace_back(PageBlock::Create()); 31 } else { 32 write_queue_.emplace_back(std::move(freelist_.back())); 33 freelist_.pop_back(); 34 } 35 PERFETTO_DCHECK(write_queue_.back().size() == 0); 36 } 37 38 void PagePool::EndRead(std::vector<PageBlock> page_blocks) { 39 PERFETTO_DCHECK_THREAD(reader_thread_); 40 for (PageBlock& page_block : page_blocks) 41 page_block.Clear(); 42 43 std::lock_guard<std::mutex> lock(mutex_); 44 freelist_.insert(freelist_.end(), 45 std::make_move_iterator(page_blocks.begin()), 46 std::make_move_iterator(page_blocks.end())); 47 48 // Even if blocks in the freelist don't waste any resident memory (because 49 // the Clear() call above madvise()s them) let's avoid that in pathological 50 // cases we keep accumulating virtual address space reservations. 51 if (freelist_.size() > kMaxFreelistBlocks) 52 freelist_.erase(freelist_.begin() + kMaxFreelistBlocks, freelist_.end()); 53 } 54 55 } // namespace perfetto 56
