1 /* 2 * Copyright (C) 2017 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 #ifndef SRC_TRACED_PROBES_FTRACE_FTRACE_METADATA_H_ 18 #define SRC_TRACED_PROBES_FTRACE_FTRACE_METADATA_H_ 19 20 #include <stdint.h> 21 #include <sys/stat.h> 22 #include <unistd.h> 23 24 #include <bitset> 25 26 #include "perfetto/base/flat_set.h" 27 #include "perfetto/base/logging.h" 28 #include "perfetto/ext/traced/data_source_types.h" 29 30 namespace perfetto { 31 32 using BlockDeviceID = decltype(stat::st_dev); 33 using Inode = decltype(stat::st_ino); 34 35 // Container for tracking miscellaneous information while parsing ftrace events, 36 // scoped to an individual data source. 37 struct FtraceMetadata { 38 struct KernelAddr { KernelAddrFtraceMetadata::KernelAddr39 KernelAddr(uint64_t _addr, uint32_t _index) : addr(_addr), index(_index) {} 40 uint64_t addr = 0; 41 uint32_t index = 0; 42 43 // We never keep more than one KernelAddr entry per address in the set. This 44 // is really just a workaround for the lack of a FlatMap. 45 // The |index| is written only after the entry is added to the set, to have 46 // a monotonic value that reflects the insertion order. 47 friend bool operator<(const KernelAddr& lhs, const KernelAddr& rhs) { 48 return lhs.addr < rhs.addr; 49 } 50 friend bool operator==(const KernelAddr& lhs, const KernelAddr& rhs) { 51 return lhs.addr == rhs.addr; 52 } 53 }; 54 FtraceMetadataFtraceMetadata55 FtraceMetadata() { 56 // A sched_switch is 64 bytes, a page is 4096 bytes and we expect 57 // 2 pid's per sched_switch. 4096/64*2=128. Give it a 2x margin. 58 pids.reserve(256); 59 60 // We expect to see only a small number of task rename events. 61 rename_pids.reserve(32); 62 63 kernel_addrs.reserve(256); 64 } 65 AddDeviceFtraceMetadata66 void AddDevice(BlockDeviceID device_id) { 67 last_seen_device_id = device_id; 68 #if PERFETTO_DCHECK_IS_ON() 69 seen_device_id = true; 70 #endif 71 } 72 AddInodeFtraceMetadata73 void AddInode(Inode inode_number) { 74 #if PERFETTO_DCHECK_IS_ON() 75 PERFETTO_DCHECK(seen_device_id); 76 #endif 77 static int32_t cached_pid = 0; 78 if (!cached_pid) 79 cached_pid = getpid(); 80 81 PERFETTO_DCHECK(last_seen_common_pid); 82 PERFETTO_DCHECK(cached_pid == getpid()); 83 // Ignore own scanning activity. 84 if (cached_pid != last_seen_common_pid) { 85 inode_and_device.insert( 86 std::make_pair(inode_number, last_seen_device_id)); 87 } 88 } 89 AddRenamePidFtraceMetadata90 void AddRenamePid(int32_t pid) { rename_pids.insert(pid); } 91 AddPidFtraceMetadata92 void AddPid(int32_t pid) { 93 const size_t pid_bit = static_cast<size_t>(pid); 94 if (PERFETTO_LIKELY(pid_bit < pids_cache.size())) { 95 if (pids_cache.test(pid_bit)) 96 return; 97 pids_cache.set(pid_bit); 98 } 99 pids.insert(pid); 100 } 101 AddCommonPidFtraceMetadata102 void AddCommonPid(int32_t pid) { 103 last_seen_common_pid = pid; 104 AddPid(pid); 105 } 106 107 // Returns the index of the symbol (a monotonic counter, which is set when 108 // the symbol is inserted the first time). AddSymbolAddrFtraceMetadata109 uint32_t AddSymbolAddr(uint64_t addr) { 110 auto it_and_inserted = kernel_addrs.insert(KernelAddr(addr, 0)); 111 // Deliberately prefer a branch here to always computing and passing 112 // size + 1 to the above. 113 if (it_and_inserted.second) { 114 const auto index = static_cast<uint32_t>(kernel_addrs.size()); 115 it_and_inserted.first->index = index; 116 } 117 return it_and_inserted.first->index; 118 } 119 ClearFtraceMetadata120 void Clear() { 121 inode_and_device.clear(); 122 rename_pids.clear(); 123 pids.clear(); 124 pids_cache.reset(); 125 kernel_addrs.clear(); 126 last_kernel_addr_index_written = 0; 127 FinishEvent(); 128 } 129 FinishEventFtraceMetadata130 void FinishEvent() { 131 last_seen_device_id = 0; 132 last_seen_common_pid = 0; 133 #if PERFETTO_DCHECK_IS_ON() 134 seen_device_id = false; 135 #endif 136 } 137 138 BlockDeviceID last_seen_device_id = 0; 139 #if PERFETTO_DCHECK_IS_ON() 140 bool seen_device_id = false; 141 #endif 142 int32_t last_seen_common_pid = 0; 143 uint32_t last_kernel_addr_index_written = 0; 144 145 base::FlatSet<InodeBlockPair> inode_and_device; 146 base::FlatSet<int32_t> rename_pids; 147 base::FlatSet<int32_t> pids; 148 base::FlatSet<KernelAddr> kernel_addrs; 149 150 // This bitmap is a cache for |pids|. It speculates on the fact that on most 151 // Android kernels, PID_MAX=32768. It saves ~1-2% cpu time on high load 152 // scenarios, as AddPid() is a very hot path. 153 std::bitset<32768> pids_cache; 154 }; 155 156 } // namespace perfetto 157 158 #endif // SRC_TRACED_PROBES_FTRACE_FTRACE_METADATA_H_ 159