1 /* 2 * Copyright (C) 2014 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 #define LOG_TAG "FastThread" 18 //#define LOG_NDEBUG 0 19 20 #define ATRACE_TAG ATRACE_TAG_AUDIO 21 22 #include "Configuration.h" 23 #include <linux/futex.h> 24 #include <sys/syscall.h> 25 #include <utils/Log.h> 26 #include <utils/Trace.h> 27 #include "FastThread.h" 28 #include "FastThreadDumpState.h" 29 30 #define FAST_DEFAULT_NS 999999999L // ~1 sec: default time to sleep 31 #define FAST_HOT_IDLE_NS 1000000L // 1 ms: time to sleep while hot idling 32 #define MIN_WARMUP_CYCLES 2 // minimum number of consecutive in-range loop cycles 33 // to wait for warmup 34 #define MAX_WARMUP_CYCLES 10 // maximum number of loop cycles to wait for warmup 35 36 namespace android { 37 38 FastThread::FastThread() : Thread(false /*canCallJava*/), 39 // re-initialized to &sInitial by subclass constructor 40 mPrevious(NULL), mCurrent(NULL), 41 /* mOldTs({0, 0}), */ 42 mOldTsValid(false), 43 mSleepNs(-1), 44 mPeriodNs(0), 45 mUnderrunNs(0), 46 mOverrunNs(0), 47 mForceNs(0), 48 mWarmupNsMin(0), 49 mWarmupNsMax(LONG_MAX), 50 // re-initialized to &mDummySubclassDumpState by subclass constructor 51 mDummyDumpState(NULL), 52 mDumpState(NULL), 53 mIgnoreNextOverrun(true), 54 #ifdef FAST_THREAD_STATISTICS 55 // mOldLoad 56 mOldLoadValid(false), 57 mBounds(0), 58 mFull(false), 59 // mTcu 60 #endif 61 mColdGen(0), 62 mIsWarm(false), 63 /* mMeasuredWarmupTs({0, 0}), */ 64 mWarmupCycles(0), 65 mWarmupConsecutiveInRangeCycles(0), 66 // mDummyLogWriter 67 mLogWriter(&mDummyLogWriter), 68 mTimestampStatus(INVALID_OPERATION), 69 70 mCommand(FastThreadState::INITIAL), 71 #if 0 72 frameCount(0), 73 #endif 74 mAttemptedWrite(false) 75 { 76 mOldTs.tv_sec = 0; 77 mOldTs.tv_nsec = 0; 78 mMeasuredWarmupTs.tv_sec = 0; 79 mMeasuredWarmupTs.tv_nsec = 0; 80 } 81 82 FastThread::~FastThread() 83 { 84 } 85 86 bool FastThread::threadLoop() 87 { 88 for (;;) { 89 90 // either nanosleep, sched_yield, or busy wait 91 if (mSleepNs >= 0) { 92 if (mSleepNs > 0) { 93 ALOG_ASSERT(mSleepNs < 1000000000); 94 const struct timespec req = {0, mSleepNs}; 95 nanosleep(&req, NULL); 96 } else { 97 sched_yield(); 98 } 99 } 100 // default to long sleep for next cycle 101 mSleepNs = FAST_DEFAULT_NS; 102 103 // poll for state change 104 const FastThreadState *next = poll(); 105 if (next == NULL) { 106 // continue to use the default initial state until a real state is available 107 // FIXME &sInitial not available, should save address earlier 108 //ALOG_ASSERT(mCurrent == &sInitial && previous == &sInitial); 109 next = mCurrent; 110 } 111 112 mCommand = next->mCommand; 113 if (next != mCurrent) { 114 115 // As soon as possible of learning of a new dump area, start using it 116 mDumpState = next->mDumpState != NULL ? next->mDumpState : mDummyDumpState; 117 mLogWriter = next->mNBLogWriter != NULL ? next->mNBLogWriter : &mDummyLogWriter; 118 setLog(mLogWriter); 119 120 // We want to always have a valid reference to the previous (non-idle) state. 121 // However, the state queue only guarantees access to current and previous states. 122 // So when there is a transition from a non-idle state into an idle state, we make a 123 // copy of the last known non-idle state so it is still available on return from idle. 124 // The possible transitions are: 125 // non-idle -> non-idle update previous from current in-place 126 // non-idle -> idle update previous from copy of current 127 // idle -> idle don't update previous 128 // idle -> non-idle don't update previous 129 if (!(mCurrent->mCommand & FastThreadState::IDLE)) { 130 if (mCommand & FastThreadState::IDLE) { 131 onIdle(); 132 mOldTsValid = false; 133 #ifdef FAST_THREAD_STATISTICS 134 mOldLoadValid = false; 135 #endif 136 mIgnoreNextOverrun = true; 137 } 138 mPrevious = mCurrent; 139 } 140 mCurrent = next; 141 } 142 #if !LOG_NDEBUG 143 next = NULL; // not referenced again 144 #endif 145 146 mDumpState->mCommand = mCommand; 147 148 // FIXME what does this comment mean? 149 // << current, previous, command, dumpState >> 150 151 switch (mCommand) { 152 case FastThreadState::INITIAL: 153 case FastThreadState::HOT_IDLE: 154 mSleepNs = FAST_HOT_IDLE_NS; 155 continue; 156 case FastThreadState::COLD_IDLE: 157 // only perform a cold idle command once 158 // FIXME consider checking previous state and only perform if previous != COLD_IDLE 159 if (mCurrent->mColdGen != mColdGen) { 160 int32_t *coldFutexAddr = mCurrent->mColdFutexAddr; 161 ALOG_ASSERT(coldFutexAddr != NULL); 162 int32_t old = android_atomic_dec(coldFutexAddr); 163 if (old <= 0) { 164 syscall(__NR_futex, coldFutexAddr, FUTEX_WAIT_PRIVATE, old - 1, NULL); 165 } 166 int policy = sched_getscheduler(0); 167 if (!(policy == SCHED_FIFO || policy == SCHED_RR)) { 168 ALOGE("did not receive expected priority boost"); 169 } 170 // This may be overly conservative; there could be times that the normal mixer 171 // requests such a brief cold idle that it doesn't require resetting this flag. 172 mIsWarm = false; 173 mMeasuredWarmupTs.tv_sec = 0; 174 mMeasuredWarmupTs.tv_nsec = 0; 175 mWarmupCycles = 0; 176 mWarmupConsecutiveInRangeCycles = 0; 177 mSleepNs = -1; 178 mColdGen = mCurrent->mColdGen; 179 #ifdef FAST_THREAD_STATISTICS 180 mBounds = 0; 181 mFull = false; 182 #endif 183 mOldTsValid = !clock_gettime(CLOCK_MONOTONIC, &mOldTs); 184 mTimestampStatus = INVALID_OPERATION; 185 } else { 186 mSleepNs = FAST_HOT_IDLE_NS; 187 } 188 continue; 189 case FastThreadState::EXIT: 190 onExit(); 191 return false; 192 default: 193 LOG_ALWAYS_FATAL_IF(!isSubClassCommand(mCommand)); 194 break; 195 } 196 197 // there is a non-idle state available to us; did the state change? 198 if (mCurrent != mPrevious) { 199 onStateChange(); 200 #if 1 // FIXME shouldn't need this 201 // only process state change once 202 mPrevious = mCurrent; 203 #endif 204 } 205 206 // do work using current state here 207 mAttemptedWrite = false; 208 onWork(); 209 210 // To be exactly periodic, compute the next sleep time based on current time. 211 // This code doesn't have long-term stability when the sink is non-blocking. 212 // FIXME To avoid drift, use the local audio clock or watch the sink's fill status. 213 struct timespec newTs; 214 int rc = clock_gettime(CLOCK_MONOTONIC, &newTs); 215 if (rc == 0) { 216 //mLogWriter->logTimestamp(newTs); 217 if (mOldTsValid) { 218 time_t sec = newTs.tv_sec - mOldTs.tv_sec; 219 long nsec = newTs.tv_nsec - mOldTs.tv_nsec; 220 ALOGE_IF(sec < 0 || (sec == 0 && nsec < 0), 221 "clock_gettime(CLOCK_MONOTONIC) failed: was %ld.%09ld but now %ld.%09ld", 222 mOldTs.tv_sec, mOldTs.tv_nsec, newTs.tv_sec, newTs.tv_nsec); 223 if (nsec < 0) { 224 --sec; 225 nsec += 1000000000; 226 } 227 // To avoid an initial underrun on fast tracks after exiting standby, 228 // do not start pulling data from tracks and mixing until warmup is complete. 229 // Warmup is considered complete after the earlier of: 230 // MIN_WARMUP_CYCLES consecutive in-range write() attempts, 231 // where "in-range" means mWarmupNsMin <= cycle time <= mWarmupNsMax 232 // MAX_WARMUP_CYCLES write() attempts. 233 // This is overly conservative, but to get better accuracy requires a new HAL API. 234 if (!mIsWarm && mAttemptedWrite) { 235 mMeasuredWarmupTs.tv_sec += sec; 236 mMeasuredWarmupTs.tv_nsec += nsec; 237 if (mMeasuredWarmupTs.tv_nsec >= 1000000000) { 238 mMeasuredWarmupTs.tv_sec++; 239 mMeasuredWarmupTs.tv_nsec -= 1000000000; 240 } 241 ++mWarmupCycles; 242 if (mWarmupNsMin <= nsec && nsec <= mWarmupNsMax) { 243 ALOGV("warmup cycle %d in range: %.03f ms", mWarmupCycles, nsec * 1e-9); 244 ++mWarmupConsecutiveInRangeCycles; 245 } else { 246 ALOGV("warmup cycle %d out of range: %.03f ms", mWarmupCycles, nsec * 1e-9); 247 mWarmupConsecutiveInRangeCycles = 0; 248 } 249 if ((mWarmupConsecutiveInRangeCycles >= MIN_WARMUP_CYCLES) || 250 (mWarmupCycles >= MAX_WARMUP_CYCLES)) { 251 mIsWarm = true; 252 mDumpState->mMeasuredWarmupTs = mMeasuredWarmupTs; 253 mDumpState->mWarmupCycles = mWarmupCycles; 254 } 255 } 256 mSleepNs = -1; 257 if (mIsWarm) { 258 if (sec > 0 || nsec > mUnderrunNs) { 259 ATRACE_NAME("underrun"); 260 // FIXME only log occasionally 261 ALOGV("underrun: time since last cycle %d.%03ld sec", 262 (int) sec, nsec / 1000000L); 263 mDumpState->mUnderruns++; 264 mIgnoreNextOverrun = true; 265 } else if (nsec < mOverrunNs) { 266 if (mIgnoreNextOverrun) { 267 mIgnoreNextOverrun = false; 268 } else { 269 // FIXME only log occasionally 270 ALOGV("overrun: time since last cycle %d.%03ld sec", 271 (int) sec, nsec / 1000000L); 272 mDumpState->mOverruns++; 273 } 274 // This forces a minimum cycle time. It: 275 // - compensates for an audio HAL with jitter due to sample rate conversion 276 // - works with a variable buffer depth audio HAL that never pulls at a 277 // rate < than mOverrunNs per buffer. 278 // - recovers from overrun immediately after underrun 279 // It doesn't work with a non-blocking audio HAL. 280 mSleepNs = mForceNs - nsec; 281 } else { 282 mIgnoreNextOverrun = false; 283 } 284 } 285 #ifdef FAST_THREAD_STATISTICS 286 if (mIsWarm) { 287 // advance the FIFO queue bounds 288 size_t i = mBounds & (mDumpState->mSamplingN - 1); 289 mBounds = (mBounds & 0xFFFF0000) | ((mBounds + 1) & 0xFFFF); 290 if (mFull) { 291 mBounds += 0x10000; 292 } else if (!(mBounds & (mDumpState->mSamplingN - 1))) { 293 mFull = true; 294 } 295 // compute the delta value of clock_gettime(CLOCK_MONOTONIC) 296 uint32_t monotonicNs = nsec; 297 if (sec > 0 && sec < 4) { 298 monotonicNs += sec * 1000000000; 299 } 300 // compute raw CPU load = delta value of clock_gettime(CLOCK_THREAD_CPUTIME_ID) 301 uint32_t loadNs = 0; 302 struct timespec newLoad; 303 rc = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &newLoad); 304 if (rc == 0) { 305 if (mOldLoadValid) { 306 sec = newLoad.tv_sec - mOldLoad.tv_sec; 307 nsec = newLoad.tv_nsec - mOldLoad.tv_nsec; 308 if (nsec < 0) { 309 --sec; 310 nsec += 1000000000; 311 } 312 loadNs = nsec; 313 if (sec > 0 && sec < 4) { 314 loadNs += sec * 1000000000; 315 } 316 } else { 317 // first time through the loop 318 mOldLoadValid = true; 319 } 320 mOldLoad = newLoad; 321 } 322 #ifdef CPU_FREQUENCY_STATISTICS 323 // get the absolute value of CPU clock frequency in kHz 324 int cpuNum = sched_getcpu(); 325 uint32_t kHz = mTcu.getCpukHz(cpuNum); 326 kHz = (kHz << 4) | (cpuNum & 0xF); 327 #endif 328 // save values in FIFO queues for dumpsys 329 // these stores #1, #2, #3 are not atomic with respect to each other, 330 // or with respect to store #4 below 331 mDumpState->mMonotonicNs[i] = monotonicNs; 332 mDumpState->mLoadNs[i] = loadNs; 333 #ifdef CPU_FREQUENCY_STATISTICS 334 mDumpState->mCpukHz[i] = kHz; 335 #endif 336 // this store #4 is not atomic with respect to stores #1, #2, #3 above, but 337 // the newest open & oldest closed halves are atomic with respect to each other 338 mDumpState->mBounds = mBounds; 339 ATRACE_INT("cycle_ms", monotonicNs / 1000000); 340 ATRACE_INT("load_us", loadNs / 1000); 341 } 342 #endif 343 } else { 344 // first time through the loop 345 mOldTsValid = true; 346 mSleepNs = mPeriodNs; 347 mIgnoreNextOverrun = true; 348 } 349 mOldTs = newTs; 350 } else { 351 // monotonic clock is broken 352 mOldTsValid = false; 353 mSleepNs = mPeriodNs; 354 } 355 356 } // for (;;) 357 358 // never return 'true'; Thread::_threadLoop() locks mutex which can result in priority inversion 359 } 360 361 } // namespace android 362
