1 /* 2 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "runtime/advancedThresholdPolicy.hpp" 27 #include "runtime/simpleThresholdPolicy.inline.hpp" 28 29 #ifdef TIERED 30 // Print an event. 31 void AdvancedThresholdPolicy::print_specific(EventType type, methodHandle mh, methodHandle imh, 32 int bci, CompLevel level) { 33 tty->print(" rate="); 34 if (mh->prev_time() == 0) tty->print("n/a"); 35 else tty->print("%f", mh->rate()); 36 37 tty->print(" k=%.2lf,%.2lf", threshold_scale(CompLevel_full_profile, Tier3LoadFeedback), 38 threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback)); 39 40 } 41 42 void AdvancedThresholdPolicy::initialize() { 43 // Turn on ergonomic compiler count selection 44 if (FLAG_IS_DEFAULT(CICompilerCountPerCPU) && FLAG_IS_DEFAULT(CICompilerCount)) { 45 FLAG_SET_DEFAULT(CICompilerCountPerCPU, true); 46 } 47 int count = CICompilerCount; 48 if (CICompilerCountPerCPU) { 49 // Simple log n seems to grow too slowly for tiered, try something faster: log n * log log n 50 int log_cpu = log2_intptr(os::active_processor_count()); 51 int loglog_cpu = log2_intptr(MAX2(log_cpu, 1)); 52 count = MAX2(log_cpu * loglog_cpu, 1) * 3 / 2; 53 } 54 55 set_c1_count(MAX2(count / 3, 1)); 56 set_c2_count(MAX2(count - count / 3, 1)); 57 58 // Some inlining tuning 59 #ifdef X86 60 if (FLAG_IS_DEFAULT(InlineSmallCode)) { 61 FLAG_SET_DEFAULT(InlineSmallCode, 2000); 62 } 63 #endif 64 65 #ifdef SPARC 66 if (FLAG_IS_DEFAULT(InlineSmallCode)) { 67 FLAG_SET_DEFAULT(InlineSmallCode, 2500); 68 } 69 #endif 70 71 set_increase_threshold_at_ratio(); 72 set_start_time(os::javaTimeMillis()); 73 } 74 75 // update_rate() is called from select_task() while holding a compile queue lock. 76 void AdvancedThresholdPolicy::update_rate(jlong t, Method* m) { 77 JavaThread* THREAD = JavaThread::current(); 78 if (is_old(m)) { 79 // We don't remove old methods from the queue, 80 // so we can just zero the rate. 81 m->set_rate(0, THREAD); 82 return; 83 } 84 85 // We don't update the rate if we've just came out of a safepoint. 86 // delta_s is the time since last safepoint in milliseconds. 87 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint(); 88 jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement 89 // How many events were there since the last time? 90 int event_count = m->invocation_count() + m->backedge_count(); 91 int delta_e = event_count - m->prev_event_count(); 92 93 // We should be running for at least 1ms. 94 if (delta_s >= TieredRateUpdateMinTime) { 95 // And we must've taken the previous point at least 1ms before. 96 if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) { 97 m->set_prev_time(t, THREAD); 98 m->set_prev_event_count(event_count, THREAD); 99 m->set_rate((float)delta_e / (float)delta_t, THREAD); // Rate is events per millisecond 100 } else 101 if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) { 102 // If nothing happened for 25ms, zero the rate. Don't modify prev values. 103 m->set_rate(0, THREAD); 104 } 105 } 106 } 107 108 // Check if this method has been stale from a given number of milliseconds. 109 // See select_task(). 110 bool AdvancedThresholdPolicy::is_stale(jlong t, jlong timeout, Method* m) { 111 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint(); 112 jlong delta_t = t - m->prev_time(); 113 if (delta_t > timeout && delta_s > timeout) { 114 int event_count = m->invocation_count() + m->backedge_count(); 115 int delta_e = event_count - m->prev_event_count(); 116 // Return true if there were no events. 117 return delta_e == 0; 118 } 119 return false; 120 } 121 122 // We don't remove old methods from the compile queue even if they have 123 // very low activity. See select_task(). 124 bool AdvancedThresholdPolicy::is_old(Method* method) { 125 return method->invocation_count() > 50000 || method->backedge_count() > 500000; 126 } 127 128 double AdvancedThresholdPolicy::weight(Method* method) { 129 return (method->rate() + 1) * ((method->invocation_count() + 1) * (method->backedge_count() + 1)); 130 } 131 132 // Apply heuristics and return true if x should be compiled before y 133 bool AdvancedThresholdPolicy::compare_methods(Method* x, Method* y) { 134 if (x->highest_comp_level() > y->highest_comp_level()) { 135 // recompilation after deopt 136 return true; 137 } else 138 if (x->highest_comp_level() == y->highest_comp_level()) { 139 if (weight(x) > weight(y)) { 140 return true; 141 } 142 } 143 return false; 144 } 145 146 // Is method profiled enough? 147 bool AdvancedThresholdPolicy::is_method_profiled(Method* method) { 148 MethodData* mdo = method->method_data(); 149 if (mdo != NULL) { 150 int i = mdo->invocation_count_delta(); 151 int b = mdo->backedge_count_delta(); 152 return call_predicate_helper<CompLevel_full_profile>(i, b, 1); 153 } 154 return false; 155 } 156 157 // Called with the queue locked and with at least one element 158 CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) { 159 CompileTask *max_task = NULL; 160 Method* max_method = NULL; 161 jlong t = os::javaTimeMillis(); 162 // Iterate through the queue and find a method with a maximum rate. 163 for (CompileTask* task = compile_queue->first(); task != NULL;) { 164 CompileTask* next_task = task->next(); 165 Method* method = task->method(); 166 MethodData* mdo = method->method_data(); 167 update_rate(t, method); 168 if (max_task == NULL) { 169 max_task = task; 170 max_method = method; 171 } else { 172 // If a method has been stale for some time, remove it from the queue. 173 if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) { 174 if (PrintTieredEvents) { 175 print_event(REMOVE_FROM_QUEUE, method, method, task->osr_bci(), (CompLevel)task->comp_level()); 176 } 177 CompileTaskWrapper ctw(task); // Frees the task 178 compile_queue->remove(task); 179 method->clear_queued_for_compilation(); 180 task = next_task; 181 continue; 182 } 183 184 // Select a method with a higher rate 185 if (compare_methods(method, max_method)) { 186 max_task = task; 187 max_method = method; 188 } 189 } 190 task = next_task; 191 } 192 193 if (max_task->comp_level() == CompLevel_full_profile && TieredStopAtLevel > CompLevel_full_profile 194 && is_method_profiled(max_method)) { 195 max_task->set_comp_level(CompLevel_limited_profile); 196 if (PrintTieredEvents) { 197 print_event(UPDATE_IN_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level()); 198 } 199 } 200 201 return max_task; 202 } 203 204 double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) { 205 double queue_size = CompileBroker::queue_size(level); 206 int comp_count = compiler_count(level); 207 double k = queue_size / (feedback_k * comp_count) + 1; 208 209 // Increase C1 compile threshold when the code cache is filled more 210 // than specified by IncreaseFirstTierCompileThresholdAt percentage. 211 // The main intention is to keep enough free space for C2 compiled code 212 // to achieve peak performance if the code cache is under stress. 213 if ((TieredStopAtLevel == CompLevel_full_optimization) && (level != CompLevel_full_optimization)) { 214 double current_reverse_free_ratio = CodeCache::reverse_free_ratio(CodeCache::get_code_blob_type(level)); 215 if (current_reverse_free_ratio > _increase_threshold_at_ratio) { 216 k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio); 217 } 218 } 219 return k; 220 } 221 222 // Call and loop predicates determine whether a transition to a higher 223 // compilation level should be performed (pointers to predicate functions 224 // are passed to common()). 225 // Tier?LoadFeedback is basically a coefficient that determines of 226 // how many methods per compiler thread can be in the queue before 227 // the threshold values double. 228 bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level) { 229 switch(cur_level) { 230 case CompLevel_none: 231 case CompLevel_limited_profile: { 232 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback); 233 return loop_predicate_helper<CompLevel_none>(i, b, k); 234 } 235 case CompLevel_full_profile: { 236 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback); 237 return loop_predicate_helper<CompLevel_full_profile>(i, b, k); 238 } 239 default: 240 return true; 241 } 242 } 243 244 bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level) { 245 switch(cur_level) { 246 case CompLevel_none: 247 case CompLevel_limited_profile: { 248 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback); 249 return call_predicate_helper<CompLevel_none>(i, b, k); 250 } 251 case CompLevel_full_profile: { 252 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback); 253 return call_predicate_helper<CompLevel_full_profile>(i, b, k); 254 } 255 default: 256 return true; 257 } 258 } 259 260 // If a method is old enough and is still in the interpreter we would want to 261 // start profiling without waiting for the compiled method to arrive. 262 // We also take the load on compilers into the account. 263 bool AdvancedThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) { 264 if (cur_level == CompLevel_none && 265 CompileBroker::queue_size(CompLevel_full_optimization) <= 266 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) { 267 int i = method->invocation_count(); 268 int b = method->backedge_count(); 269 double k = Tier0ProfilingStartPercentage / 100.0; 270 return call_predicate_helper<CompLevel_none>(i, b, k) || loop_predicate_helper<CompLevel_none>(i, b, k); 271 } 272 return false; 273 } 274 275 // Inlining control: if we're compiling a profiled method with C1 and the callee 276 // is known to have OSRed in a C2 version, don't inline it. 277 bool AdvancedThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) { 278 CompLevel comp_level = (CompLevel)env->comp_level(); 279 if (comp_level == CompLevel_full_profile || 280 comp_level == CompLevel_limited_profile) { 281 return callee->highest_osr_comp_level() == CompLevel_full_optimization; 282 } 283 return false; 284 } 285 286 // Create MDO if necessary. 287 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, JavaThread* THREAD) { 288 if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return; 289 if (mh->method_data() == NULL) { 290 Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR); 291 } 292 } 293 294 295 /* 296 * Method states: 297 * 0 - interpreter (CompLevel_none) 298 * 1 - pure C1 (CompLevel_simple) 299 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile) 300 * 3 - C1 with full profiling (CompLevel_full_profile) 301 * 4 - C2 (CompLevel_full_optimization) 302 * 303 * Common state transition patterns: 304 * a. 0 -> 3 -> 4. 305 * The most common path. But note that even in this straightforward case 306 * profiling can start at level 0 and finish at level 3. 307 * 308 * b. 0 -> 2 -> 3 -> 4. 309 * This case occures when the load on C2 is deemed too high. So, instead of transitioning 310 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to 311 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs. 312 * 313 * c. 0 -> (3->2) -> 4. 314 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough 315 * to enable the profiling to fully occur at level 0. In this case we change the compilation level 316 * of the method to 2, because it'll allow it to run much faster without full profiling while c2 317 * is compiling. 318 * 319 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1. 320 * After a method was once compiled with C1 it can be identified as trivial and be compiled to 321 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1. 322 * 323 * e. 0 -> 4. 324 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter) 325 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because 326 * the compiled version already exists). 327 * 328 * Note that since state 0 can be reached from any other state via deoptimization different loops 329 * are possible. 330 * 331 */ 332 333 // Common transition function. Given a predicate determines if a method should transition to another level. 334 CompLevel AdvancedThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) { 335 CompLevel next_level = cur_level; 336 int i = method->invocation_count(); 337 int b = method->backedge_count(); 338 339 if (is_trivial(method)) { 340 next_level = CompLevel_simple; 341 } else { 342 switch(cur_level) { 343 case CompLevel_none: 344 // If we were at full profile level, would we switch to full opt? 345 if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) { 346 next_level = CompLevel_full_optimization; 347 } else if ((this->*p)(i, b, cur_level)) { 348 // C1-generated fully profiled code is about 30% slower than the limited profile 349 // code that has only invocation and backedge counters. The observation is that 350 // if C2 queue is large enough we can spend too much time in the fully profiled code 351 // while waiting for C2 to pick the method from the queue. To alleviate this problem 352 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long 353 // we choose to compile a limited profiled version and then recompile with full profiling 354 // when the load on C2 goes down. 355 if (!disable_feedback && CompileBroker::queue_size(CompLevel_full_optimization) > 356 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) { 357 next_level = CompLevel_limited_profile; 358 } else { 359 next_level = CompLevel_full_profile; 360 } 361 } 362 break; 363 case CompLevel_limited_profile: 364 if (is_method_profiled(method)) { 365 // Special case: we got here because this method was fully profiled in the interpreter. 366 next_level = CompLevel_full_optimization; 367 } else { 368 MethodData* mdo = method->method_data(); 369 if (mdo != NULL) { 370 if (mdo->would_profile()) { 371 if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <= 372 Tier3DelayOff * compiler_count(CompLevel_full_optimization) && 373 (this->*p)(i, b, cur_level))) { 374 next_level = CompLevel_full_profile; 375 } 376 } else { 377 next_level = CompLevel_full_optimization; 378 } 379 } 380 } 381 break; 382 case CompLevel_full_profile: 383 { 384 MethodData* mdo = method->method_data(); 385 if (mdo != NULL) { 386 if (mdo->would_profile()) { 387 int mdo_i = mdo->invocation_count_delta(); 388 int mdo_b = mdo->backedge_count_delta(); 389 if ((this->*p)(mdo_i, mdo_b, cur_level)) { 390 next_level = CompLevel_full_optimization; 391 } 392 } else { 393 next_level = CompLevel_full_optimization; 394 } 395 } 396 } 397 break; 398 } 399 } 400 return MIN2(next_level, (CompLevel)TieredStopAtLevel); 401 } 402 403 // Determine if a method should be compiled with a normal entry point at a different level. 404 CompLevel AdvancedThresholdPolicy::call_event(Method* method, CompLevel cur_level) { 405 CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(), 406 common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true)); 407 CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level); 408 409 // If OSR method level is greater than the regular method level, the levels should be 410 // equalized by raising the regular method level in order to avoid OSRs during each 411 // invocation of the method. 412 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) { 413 MethodData* mdo = method->method_data(); 414 guarantee(mdo != NULL, "MDO should not be NULL"); 415 if (mdo->invocation_count() >= 1) { 416 next_level = CompLevel_full_optimization; 417 } 418 } else { 419 next_level = MAX2(osr_level, next_level); 420 } 421 return next_level; 422 } 423 424 // Determine if we should do an OSR compilation of a given method. 425 CompLevel AdvancedThresholdPolicy::loop_event(Method* method, CompLevel cur_level) { 426 CompLevel next_level = common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true); 427 if (cur_level == CompLevel_none) { 428 // If there is a live OSR method that means that we deopted to the interpreter 429 // for the transition. 430 CompLevel osr_level = MIN2((CompLevel)method->highest_osr_comp_level(), next_level); 431 if (osr_level > CompLevel_none) { 432 return osr_level; 433 } 434 } 435 return next_level; 436 } 437 438 // Update the rate and submit compile 439 void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, JavaThread* thread) { 440 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count(); 441 update_rate(os::javaTimeMillis(), mh()); 442 CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", thread); 443 } 444 445 // Handle the invocation event. 446 void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh, 447 CompLevel level, nmethod* nm, JavaThread* thread) { 448 if (should_create_mdo(mh(), level)) { 449 create_mdo(mh, thread); 450 } 451 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, InvocationEntryBci)) { 452 CompLevel next_level = call_event(mh(), level); 453 if (next_level != level) { 454 compile(mh, InvocationEntryBci, next_level, thread); 455 } 456 } 457 } 458 459 // Handle the back branch event. Notice that we can compile the method 460 // with a regular entry from here. 461 void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh, 462 int bci, CompLevel level, nmethod* nm, JavaThread* thread) { 463 if (should_create_mdo(mh(), level)) { 464 create_mdo(mh, thread); 465 } 466 // Check if MDO should be created for the inlined method 467 if (should_create_mdo(imh(), level)) { 468 create_mdo(imh, thread); 469 } 470 471 if (is_compilation_enabled()) { 472 CompLevel next_osr_level = loop_event(imh(), level); 473 CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level(); 474 // At the very least compile the OSR version 475 if (!CompileBroker::compilation_is_in_queue(imh, bci) && next_osr_level != level) { 476 compile(imh, bci, next_osr_level, thread); 477 } 478 479 // Use loop event as an opportunity to also check if there's been 480 // enough calls. 481 CompLevel cur_level, next_level; 482 if (mh() != imh()) { // If there is an enclosing method 483 guarantee(nm != NULL, "Should have nmethod here"); 484 cur_level = comp_level(mh()); 485 next_level = call_event(mh(), cur_level); 486 487 if (max_osr_level == CompLevel_full_optimization) { 488 // The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts 489 bool make_not_entrant = false; 490 if (nm->is_osr_method()) { 491 // This is an osr method, just make it not entrant and recompile later if needed 492 make_not_entrant = true; 493 } else { 494 if (next_level != CompLevel_full_optimization) { 495 // next_level is not full opt, so we need to recompile the 496 // enclosing method without the inlinee 497 cur_level = CompLevel_none; 498 make_not_entrant = true; 499 } 500 } 501 if (make_not_entrant) { 502 if (PrintTieredEvents) { 503 int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci; 504 print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level); 505 } 506 nm->make_not_entrant(); 507 } 508 } 509 if (!CompileBroker::compilation_is_in_queue(mh, InvocationEntryBci)) { 510 // Fix up next_level if necessary to avoid deopts 511 if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) { 512 next_level = CompLevel_full_profile; 513 } 514 if (cur_level != next_level) { 515 compile(mh, InvocationEntryBci, next_level, thread); 516 } 517 } 518 } else { 519 cur_level = comp_level(imh()); 520 next_level = call_event(imh(), cur_level); 521 if (!CompileBroker::compilation_is_in_queue(imh, bci) && next_level != cur_level) { 522 compile(imh, InvocationEntryBci, next_level, thread); 523 } 524 } 525 } 526 } 527 528 #endif // TIERED