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 - c1_count(), 1)); 57 FLAG_SET_ERGO(intx, CICompilerCount, c1_count() + c2_count()); 58 59 // Some inlining tuning 60 #ifdef X86 61 if (FLAG_IS_DEFAULT(InlineSmallCode)) { 62 FLAG_SET_DEFAULT(InlineSmallCode, 2000); 63 } 64 #endif 65 66 #ifdef SPARC 67 if (FLAG_IS_DEFAULT(InlineSmallCode)) { 68 FLAG_SET_DEFAULT(InlineSmallCode, 2500); 69 } 70 #endif 71 72 set_increase_threshold_at_ratio(); 73 set_start_time(os::javaTimeMillis()); 74 } 75 76 // update_rate() is called from select_task() while holding a compile queue lock. 77 void AdvancedThresholdPolicy::update_rate(jlong t, Method* m) { 78 // Skip update if counters are absent. 79 // Can't allocate them since we are holding compile queue lock. 80 if (m->method_counters() == NULL) return; 81 82 if (is_old(m)) { 83 // We don't remove old methods from the queue, 84 // so we can just zero the rate. 85 m->set_rate(0); 86 return; 87 } 88 89 // We don't update the rate if we've just came out of a safepoint. 90 // delta_s is the time since last safepoint in milliseconds. 91 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint(); 92 jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement 93 // How many events were there since the last time? 94 int event_count = m->invocation_count() + m->backedge_count(); 95 int delta_e = event_count - m->prev_event_count(); 96 97 // We should be running for at least 1ms. 98 if (delta_s >= TieredRateUpdateMinTime) { 99 // And we must've taken the previous point at least 1ms before. 100 if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) { 101 m->set_prev_time(t); 102 m->set_prev_event_count(event_count); 103 m->set_rate((float)delta_e / (float)delta_t); // Rate is events per millisecond 104 } else { 105 if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) { 106 // If nothing happened for 25ms, zero the rate. Don't modify prev values. 107 m->set_rate(0); 108 } 109 } 110 } 111 } 112 113 // Check if this method has been stale from a given number of milliseconds. 114 // See select_task(). 115 bool AdvancedThresholdPolicy::is_stale(jlong t, jlong timeout, Method* m) { 116 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint(); 117 jlong delta_t = t - m->prev_time(); 118 if (delta_t > timeout && delta_s > timeout) { 119 int event_count = m->invocation_count() + m->backedge_count(); 120 int delta_e = event_count - m->prev_event_count(); 121 // Return true if there were no events. 122 return delta_e == 0; 123 } 124 return false; 125 } 126 127 // We don't remove old methods from the compile queue even if they have 128 // very low activity. See select_task(). 129 bool AdvancedThresholdPolicy::is_old(Method* method) { 130 return method->invocation_count() > 50000 || method->backedge_count() > 500000; 131 } 132 133 double AdvancedThresholdPolicy::weight(Method* method) { 134 return (method->rate() + 1) * ((method->invocation_count() + 1) * (method->backedge_count() + 1)); 135 } 136 137 // Apply heuristics and return true if x should be compiled before y 138 bool AdvancedThresholdPolicy::compare_methods(Method* x, Method* y) { 139 if (x->highest_comp_level() > y->highest_comp_level()) { 140 // recompilation after deopt 141 return true; 142 } else 143 if (x->highest_comp_level() == y->highest_comp_level()) { 144 if (weight(x) > weight(y)) { 145 return true; 146 } 147 } 148 return false; 149 } 150 151 // Is method profiled enough? 152 bool AdvancedThresholdPolicy::is_method_profiled(Method* method) { 153 MethodData* mdo = method->method_data(); 154 if (mdo != NULL) { 155 int i = mdo->invocation_count_delta(); 156 int b = mdo->backedge_count_delta(); 157 return call_predicate_helper<CompLevel_full_profile>(i, b, 1); 158 } 159 return false; 160 } 161 162 // Called with the queue locked and with at least one element 163 CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) { 164 CompileTask *max_task = NULL; 165 Method* max_method = NULL; 166 jlong t = os::javaTimeMillis(); 167 // Iterate through the queue and find a method with a maximum rate. 168 for (CompileTask* task = compile_queue->first(); task != NULL;) { 169 CompileTask* next_task = task->next(); 170 Method* method = task->method(); 171 update_rate(t, method); 172 if (max_task == NULL) { 173 max_task = task; 174 max_method = method; 175 } else { 176 // If a method has been stale for some time, remove it from the queue. 177 if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) { 178 if (PrintTieredEvents) { 179 print_event(REMOVE_FROM_QUEUE, method, method, task->osr_bci(), (CompLevel)task->comp_level()); 180 } 181 compile_queue->remove_and_mark_stale(task); 182 method->clear_queued_for_compilation(); 183 task = next_task; 184 continue; 185 } 186 187 // Select a method with a higher rate 188 if (compare_methods(method, max_method)) { 189 max_task = task; 190 max_method = method; 191 } 192 } 193 task = next_task; 194 } 195 196 if (max_task->comp_level() == CompLevel_full_profile && TieredStopAtLevel > CompLevel_full_profile 197 && is_method_profiled(max_method)) { 198 max_task->set_comp_level(CompLevel_limited_profile); 199 if (PrintTieredEvents) { 200 print_event(UPDATE_IN_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level()); 201 } 202 } 203 204 return max_task; 205 } 206 207 double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) { 208 double queue_size = CompileBroker::queue_size(level); 209 int comp_count = compiler_count(level); 210 double k = queue_size / (feedback_k * comp_count) + 1; 211 212 // Increase C1 compile threshold when the code cache is filled more 213 // than specified by IncreaseFirstTierCompileThresholdAt percentage. 214 // The main intention is to keep enough free space for C2 compiled code 215 // to achieve peak performance if the code cache is under stress. 216 if ((TieredStopAtLevel == CompLevel_full_optimization) && (level != CompLevel_full_optimization)) { 217 double current_reverse_free_ratio = CodeCache::reverse_free_ratio(); 218 if (current_reverse_free_ratio > _increase_threshold_at_ratio) { 219 k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio); 220 } 221 } 222 return k; 223 } 224 225 // Call and loop predicates determine whether a transition to a higher 226 // compilation level should be performed (pointers to predicate functions 227 // are passed to common()). 228 // Tier?LoadFeedback is basically a coefficient that determines of 229 // how many methods per compiler thread can be in the queue before 230 // the threshold values double. 231 bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level) { 232 switch(cur_level) { 233 case CompLevel_none: 234 case CompLevel_limited_profile: { 235 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback); 236 return loop_predicate_helper<CompLevel_none>(i, b, k); 237 } 238 case CompLevel_full_profile: { 239 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback); 240 return loop_predicate_helper<CompLevel_full_profile>(i, b, k); 241 } 242 default: 243 return true; 244 } 245 } 246 247 bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level) { 248 switch(cur_level) { 249 case CompLevel_none: 250 case CompLevel_limited_profile: { 251 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback); 252 return call_predicate_helper<CompLevel_none>(i, b, k); 253 } 254 case CompLevel_full_profile: { 255 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback); 256 return call_predicate_helper<CompLevel_full_profile>(i, b, k); 257 } 258 default: 259 return true; 260 } 261 } 262 263 // If a method is old enough and is still in the interpreter we would want to 264 // start profiling without waiting for the compiled method to arrive. 265 // We also take the load on compilers into the account. 266 bool AdvancedThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) { 267 if (cur_level == CompLevel_none && 268 CompileBroker::queue_size(CompLevel_full_optimization) <= 269 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) { 270 int i = method->invocation_count(); 271 int b = method->backedge_count(); 272 double k = Tier0ProfilingStartPercentage / 100.0; 273 return call_predicate_helper<CompLevel_none>(i, b, k) || loop_predicate_helper<CompLevel_none>(i, b, k); 274 } 275 return false; 276 } 277 278 // Inlining control: if we're compiling a profiled method with C1 and the callee 279 // is known to have OSRed in a C2 version, don't inline it. 280 bool AdvancedThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) { 281 CompLevel comp_level = (CompLevel)env->comp_level(); 282 if (comp_level == CompLevel_full_profile || 283 comp_level == CompLevel_limited_profile) { 284 return callee->highest_osr_comp_level() == CompLevel_full_optimization; 285 } 286 return false; 287 } 288 289 // Create MDO if necessary. 290 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, JavaThread* THREAD) { 291 if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return; 292 if (mh->method_data() == NULL) { 293 Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR); 294 } 295 } 296 297 298 /* 299 * Method states: 300 * 0 - interpreter (CompLevel_none) 301 * 1 - pure C1 (CompLevel_simple) 302 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile) 303 * 3 - C1 with full profiling (CompLevel_full_profile) 304 * 4 - C2 (CompLevel_full_optimization) 305 * 306 * Common state transition patterns: 307 * a. 0 -> 3 -> 4. 308 * The most common path. But note that even in this straightforward case 309 * profiling can start at level 0 and finish at level 3. 310 * 311 * b. 0 -> 2 -> 3 -> 4. 312 * This case occures when the load on C2 is deemed too high. So, instead of transitioning 313 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to 314 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs. 315 * 316 * c. 0 -> (3->2) -> 4. 317 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough 318 * to enable the profiling to fully occur at level 0. In this case we change the compilation level 319 * of the method to 2 while the request is still in-queue, because it'll allow it to run much faster 320 * without full profiling while c2 is compiling. 321 * 322 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1. 323 * After a method was once compiled with C1 it can be identified as trivial and be compiled to 324 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1. 325 * 326 * e. 0 -> 4. 327 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter) 328 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because 329 * the compiled version already exists). 330 * 331 * Note that since state 0 can be reached from any other state via deoptimization different loops 332 * are possible. 333 * 334 */ 335 336 // Common transition function. Given a predicate determines if a method should transition to another level. 337 CompLevel AdvancedThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) { 338 CompLevel next_level = cur_level; 339 int i = method->invocation_count(); 340 int b = method->backedge_count(); 341 342 if (is_trivial(method)) { 343 next_level = CompLevel_simple; 344 } else { 345 switch(cur_level) { 346 case CompLevel_none: 347 // If we were at full profile level, would we switch to full opt? 348 if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) { 349 next_level = CompLevel_full_optimization; 350 } else if ((this->*p)(i, b, cur_level)) { 351 // C1-generated fully profiled code is about 30% slower than the limited profile 352 // code that has only invocation and backedge counters. The observation is that 353 // if C2 queue is large enough we can spend too much time in the fully profiled code 354 // while waiting for C2 to pick the method from the queue. To alleviate this problem 355 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long 356 // we choose to compile a limited profiled version and then recompile with full profiling 357 // when the load on C2 goes down. 358 if (!disable_feedback && CompileBroker::queue_size(CompLevel_full_optimization) > 359 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) { 360 next_level = CompLevel_limited_profile; 361 } else { 362 next_level = CompLevel_full_profile; 363 } 364 } 365 break; 366 case CompLevel_limited_profile: 367 if (is_method_profiled(method)) { 368 // Special case: we got here because this method was fully profiled in the interpreter. 369 next_level = CompLevel_full_optimization; 370 } else { 371 MethodData* mdo = method->method_data(); 372 if (mdo != NULL) { 373 if (mdo->would_profile()) { 374 if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <= 375 Tier3DelayOff * compiler_count(CompLevel_full_optimization) && 376 (this->*p)(i, b, cur_level))) { 377 next_level = CompLevel_full_profile; 378 } 379 } else { 380 next_level = CompLevel_full_optimization; 381 } 382 } 383 } 384 break; 385 case CompLevel_full_profile: 386 { 387 MethodData* mdo = method->method_data(); 388 if (mdo != NULL) { 389 if (mdo->would_profile()) { 390 int mdo_i = mdo->invocation_count_delta(); 391 int mdo_b = mdo->backedge_count_delta(); 392 if ((this->*p)(mdo_i, mdo_b, cur_level)) { 393 next_level = CompLevel_full_optimization; 394 } 395 } else { 396 next_level = CompLevel_full_optimization; 397 } 398 } 399 } 400 break; 401 } 402 } 403 return MIN2(next_level, (CompLevel)TieredStopAtLevel); 404 } 405 406 // Determine if a method should be compiled with a normal entry point at a different level. 407 CompLevel AdvancedThresholdPolicy::call_event(Method* method, CompLevel cur_level) { 408 CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(), 409 common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true)); 410 CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level); 411 412 // If OSR method level is greater than the regular method level, the levels should be 413 // equalized by raising the regular method level in order to avoid OSRs during each 414 // invocation of the method. 415 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) { 416 MethodData* mdo = method->method_data(); 417 guarantee(mdo != NULL, "MDO should not be NULL"); 418 if (mdo->invocation_count() >= 1) { 419 next_level = CompLevel_full_optimization; 420 } 421 } else { 422 next_level = MAX2(osr_level, next_level); 423 } 424 return next_level; 425 } 426 427 // Determine if we should do an OSR compilation of a given method. 428 CompLevel AdvancedThresholdPolicy::loop_event(Method* method, CompLevel cur_level) { 429 CompLevel next_level = common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true); 430 if (cur_level == CompLevel_none) { 431 // If there is a live OSR method that means that we deopted to the interpreter 432 // for the transition. 433 CompLevel osr_level = MIN2((CompLevel)method->highest_osr_comp_level(), next_level); 434 if (osr_level > CompLevel_none) { 435 return osr_level; 436 } 437 } 438 return next_level; 439 } 440 441 // Update the rate and submit compile 442 void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, JavaThread* thread) { 443 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count(); 444 update_rate(os::javaTimeMillis(), mh()); 445 CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", thread); 446 } 447 448 // Handle the invocation event. 449 void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh, 450 CompLevel level, nmethod* nm, JavaThread* thread) { 451 if (should_create_mdo(mh(), level)) { 452 create_mdo(mh, thread); 453 } 454 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh)) { 455 CompLevel next_level = call_event(mh(), level); 456 if (next_level != level) { 457 compile(mh, InvocationEntryBci, next_level, thread); 458 } 459 } 460 } 461 462 // Handle the back branch event. Notice that we can compile the method 463 // with a regular entry from here. 464 void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh, 465 int bci, CompLevel level, nmethod* nm, JavaThread* thread) { 466 if (should_create_mdo(mh(), level)) { 467 create_mdo(mh, thread); 468 } 469 // Check if MDO should be created for the inlined method 470 if (should_create_mdo(imh(), level)) { 471 create_mdo(imh, thread); 472 } 473 474 if (is_compilation_enabled()) { 475 CompLevel next_osr_level = loop_event(imh(), level); 476 CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level(); 477 // At the very least compile the OSR version 478 if (!CompileBroker::compilation_is_in_queue(imh) && (next_osr_level != level)) { 479 compile(imh, bci, next_osr_level, thread); 480 } 481 482 // Use loop event as an opportunity to also check if there's been 483 // enough calls. 484 CompLevel cur_level, next_level; 485 if (mh() != imh()) { // If there is an enclosing method 486 guarantee(nm != NULL, "Should have nmethod here"); 487 cur_level = comp_level(mh()); 488 next_level = call_event(mh(), cur_level); 489 490 if (max_osr_level == CompLevel_full_optimization) { 491 // The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts 492 bool make_not_entrant = false; 493 if (nm->is_osr_method()) { 494 // This is an osr method, just make it not entrant and recompile later if needed 495 make_not_entrant = true; 496 } else { 497 if (next_level != CompLevel_full_optimization) { 498 // next_level is not full opt, so we need to recompile the 499 // enclosing method without the inlinee 500 cur_level = CompLevel_none; 501 make_not_entrant = true; 502 } 503 } 504 if (make_not_entrant) { 505 if (PrintTieredEvents) { 506 int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci; 507 print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level); 508 } 509 nm->make_not_entrant(); 510 } 511 } 512 if (!CompileBroker::compilation_is_in_queue(mh)) { 513 // Fix up next_level if necessary to avoid deopts 514 if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) { 515 next_level = CompLevel_full_profile; 516 } 517 if (cur_level != next_level) { 518 compile(mh, InvocationEntryBci, next_level, thread); 519 } 520 } 521 } else { 522 cur_level = comp_level(imh()); 523 next_level = call_event(imh(), cur_level); 524 if (!CompileBroker::compilation_is_in_queue(imh) && (next_level != cur_level)) { 525 compile(imh, InvocationEntryBci, next_level, thread); 526 } 527 } 528 } 529 } 530 531 #endif // TIERED