1 /*
2 * Copyright (c) 2010, 2015, 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 "code/codeCache.hpp"
27 #include "compiler/compileTask.hpp"
28 #include "runtime/advancedThresholdPolicy.hpp"
29 #include "runtime/simpleThresholdPolicy.inline.hpp"
30
31 #ifdef TIERED
32 // Print an event.
33 void AdvancedThresholdPolicy::print_specific(EventType type, methodHandle mh, methodHandle imh,
34 int bci, CompLevel level) {
35 tty->print(" rate=");
36 if (mh->prev_time() == 0) tty->print("n/a");
37 else tty->print("%f", mh->rate());
38
39 tty->print(" k=%.2lf,%.2lf", threshold_scale(CompLevel_full_profile, Tier3LoadFeedback),
40 threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));
41
42 }
43
44 void AdvancedThresholdPolicy::initialize() {
45 // Turn on ergonomic compiler count selection
46 if (FLAG_IS_DEFAULT(CICompilerCountPerCPU) && FLAG_IS_DEFAULT(CICompilerCount)) {
47 FLAG_SET_DEFAULT(CICompilerCountPerCPU, true);
48 }
49 int count = CICompilerCount;
50 if (CICompilerCountPerCPU) {
51 // Simple log n seems to grow too slowly for tiered, try something faster: log n * log log n
52 int log_cpu = log2_intptr(os::active_processor_count());
53 int loglog_cpu = log2_intptr(MAX2(log_cpu, 1));
54 count = MAX2(log_cpu * loglog_cpu, 1) * 3 / 2;
55 }
56
57 set_c1_count(MAX2(count / 3, 1));
58 set_c2_count(MAX2(count - c1_count(), 1));
59 FLAG_SET_ERGO(intx, CICompilerCount, c1_count() + c2_count());
60
61 // Some inlining tuning
62 #ifdef X86
63 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
64 FLAG_SET_DEFAULT(InlineSmallCode, 2000);
65 }
66 #endif
67
68 #if defined SPARC || defined AARCH64
69 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
70 FLAG_SET_DEFAULT(InlineSmallCode, 2500);
71 }
72 #endif
73
74 set_increase_threshold_at_ratio();
75 set_start_time(os::javaTimeMillis());
76 }
77
78 // update_rate() is called from select_task() while holding a compile queue lock.
79 void AdvancedThresholdPolicy::update_rate(jlong t, Method* m) {
80 // Skip update if counters are absent.
81 // Can't allocate them since we are holding compile queue lock.
82 if (m->method_counters() == NULL) return;
83
84 if (is_old(m)) {
85 // We don't remove old methods from the queue,
86 // so we can just zero the rate.
87 m->set_rate(0);
88 return;
89 }
90
91 // We don't update the rate if we've just came out of a safepoint.
92 // delta_s is the time since last safepoint in milliseconds.
93 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
94 jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement
95 // How many events were there since the last time?
96 int event_count = m->invocation_count() + m->backedge_count();
97 int delta_e = event_count - m->prev_event_count();
98
99 // We should be running for at least 1ms.
100 if (delta_s >= TieredRateUpdateMinTime) {
101 // And we must've taken the previous point at least 1ms before.
102 if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) {
103 m->set_prev_time(t);
104 m->set_prev_event_count(event_count);
105 m->set_rate((float)delta_e / (float)delta_t); // Rate is events per millisecond
106 } else {
107 if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) {
108 // If nothing happened for 25ms, zero the rate. Don't modify prev values.
109 m->set_rate(0);
110 }
111 }
112 }
113 }
114
115 // Check if this method has been stale from a given number of milliseconds.
116 // See select_task().
117 bool AdvancedThresholdPolicy::is_stale(jlong t, jlong timeout, Method* m) {
118 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
119 jlong delta_t = t - m->prev_time();
120 if (delta_t > timeout && delta_s > timeout) {
121 int event_count = m->invocation_count() + m->backedge_count();
122 int delta_e = event_count - m->prev_event_count();
123 // Return true if there were no events.
124 return delta_e == 0;
125 }
126 return false;
127 }
128
129 // We don't remove old methods from the compile queue even if they have
130 // very low activity. See select_task().
131 bool AdvancedThresholdPolicy::is_old(Method* method) {
132 return method->invocation_count() > 50000 || method->backedge_count() > 500000;
133 }
134
135 double AdvancedThresholdPolicy::weight(Method* method) {
136 return (double)(method->rate() + 1) *
137 (method->invocation_count() + 1) * (method->backedge_count() + 1);
138 }
139
140 // Apply heuristics and return true if x should be compiled before y
141 bool AdvancedThresholdPolicy::compare_methods(Method* x, Method* y) {
142 if (x->highest_comp_level() > y->highest_comp_level()) {
143 // recompilation after deopt
144 return true;
145 } else
146 if (x->highest_comp_level() == y->highest_comp_level()) {
147 if (weight(x) > weight(y)) {
148 return true;
149 }
150 }
151 return false;
152 }
153
154 // Is method profiled enough?
155 bool AdvancedThresholdPolicy::is_method_profiled(Method* method) {
156 MethodData* mdo = method->method_data();
157 if (mdo != NULL) {
158 int i = mdo->invocation_count_delta();
159 int b = mdo->backedge_count_delta();
160 return call_predicate_helper<CompLevel_full_profile>(i, b, 1, method);
161 }
162 return false;
163 }
164
165 // Called with the queue locked and with at least one element
166 CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {
167 #if INCLUDE_JVMCI
168 CompileTask *max_non_jvmci_task = NULL;
169 #endif
170 CompileTask *max_task = NULL;
171 Method* max_method = NULL;
172 jlong t = os::javaTimeMillis();
173 // Iterate through the queue and find a method with a maximum rate.
174 for (CompileTask* task = compile_queue->first(); task != NULL;) {
175 CompileTask* next_task = task->next();
176 Method* method = task->method();
177 update_rate(t, method);
178 if (max_task == NULL) {
179 max_task = task;
180 max_method = method;
181 } else {
182 // If a method has been stale for some time, remove it from the queue.
183 if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) {
184 if (PrintTieredEvents) {
185 print_event(REMOVE_FROM_QUEUE, method, method, task->osr_bci(), (CompLevel)task->comp_level());
186 }
187 task->log_task_dequeued("stale");
188 compile_queue->remove_and_mark_stale(task);
189 method->clear_queued_for_compilation();
190 task = next_task;
191 continue;
192 }
193
194 // Select a method with a higher rate
195 if (compare_methods(method, max_method)) {
196 max_task = task;
197 max_method = method;
198 }
199 }
200 task = next_task;
201 }
202
203 #if INCLUDE_JVMCI
204 if (UseJVMCICompiler) {
205 if (max_non_jvmci_task != NULL) {
206 max_task = max_non_jvmci_task;
207 max_method = max_task->method();
208 }
209 }
210 #endif
211
212 if (max_task->comp_level() == CompLevel_full_profile && TieredStopAtLevel > CompLevel_full_profile
213 && is_method_profiled(max_method)) {
214 max_task->set_comp_level(CompLevel_limited_profile);
215 if (PrintTieredEvents) {
216 print_event(UPDATE_IN_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
217 }
218 }
219
220 return max_task;
221 }
222
223 double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
224 double queue_size = CompileBroker::queue_size(level);
225 int comp_count = compiler_count(level);
226 double k = queue_size / (feedback_k * comp_count) + 1;
227
228 // Increase C1 compile threshold when the code cache is filled more
229 // than specified by IncreaseFirstTierCompileThresholdAt percentage.
230 // The main intention is to keep enough free space for C2 compiled code
231 // to achieve peak performance if the code cache is under stress.
232 if ((TieredStopAtLevel == CompLevel_full_optimization) && (level != CompLevel_full_optimization)) {
233 double current_reverse_free_ratio = CodeCache::reverse_free_ratio(CodeCache::get_code_blob_type(level));
234 if (current_reverse_free_ratio > _increase_threshold_at_ratio) {
235 k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio);
236 }
237 }
238 return k;
239 }
240
241 // Call and loop predicates determine whether a transition to a higher
242 // compilation level should be performed (pointers to predicate functions
243 // are passed to common()).
244 // Tier?LoadFeedback is basically a coefficient that determines of
245 // how many methods per compiler thread can be in the queue before
246 // the threshold values double.
247 bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level, Method* method) {
248 switch(cur_level) {
249 case CompLevel_none:
250 case CompLevel_limited_profile: {
251 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
252 return loop_predicate_helper<CompLevel_none>(i, b, k, method);
253 }
254 case CompLevel_full_profile: {
255 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
256 return loop_predicate_helper<CompLevel_full_profile>(i, b, k, method);
257 }
258 default:
259 return true;
260 }
261 }
262
263 bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level, Method* method) {
264 switch(cur_level) {
265 case CompLevel_none:
266 case CompLevel_limited_profile: {
267 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
268 return call_predicate_helper<CompLevel_none>(i, b, k, method);
269 }
270 case CompLevel_full_profile: {
271 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
272 return call_predicate_helper<CompLevel_full_profile>(i, b, k, method);
273 }
274 default:
275 return true;
276 }
277 }
278
279 // If a method is old enough and is still in the interpreter we would want to
280 // start profiling without waiting for the compiled method to arrive.
281 // We also take the load on compilers into the account.
282 bool AdvancedThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) {
283 if (cur_level == CompLevel_none &&
284 CompileBroker::queue_size(CompLevel_full_optimization) <=
285 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
286 int i = method->invocation_count();
287 int b = method->backedge_count();
288 double k = Tier0ProfilingStartPercentage / 100.0;
289 return call_predicate_helper<CompLevel_none>(i, b, k, method) || loop_predicate_helper<CompLevel_none>(i, b, k, method);
290 }
291 return false;
292 }
293
294 // Inlining control: if we're compiling a profiled method with C1 and the callee
295 // is known to have OSRed in a C2 version, don't inline it.
296 bool AdvancedThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) {
297 CompLevel comp_level = (CompLevel)env->comp_level();
298 if (comp_level == CompLevel_full_profile ||
299 comp_level == CompLevel_limited_profile) {
300 return callee->highest_osr_comp_level() == CompLevel_full_optimization;
301 }
302 return false;
303 }
304
305 // Create MDO if necessary.
306 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, JavaThread* THREAD) {
307 if (mh->is_native() ||
308 mh->is_abstract() ||
309 mh->is_accessor() ||
310 mh->is_constant_getter()) {
311 return;
312 }
313 if (mh->method_data() == NULL) {
314 Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR);
315 }
316 }
317
318
319 /*
320 * Method states:
321 * 0 - interpreter (CompLevel_none)
322 * 1 - pure C1 (CompLevel_simple)
323 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
324 * 3 - C1 with full profiling (CompLevel_full_profile)
325 * 4 - C2 (CompLevel_full_optimization)
326 *
327 * Common state transition patterns:
328 * a. 0 -> 3 -> 4.
329 * The most common path. But note that even in this straightforward case
330 * profiling can start at level 0 and finish at level 3.
331 *
332 * b. 0 -> 2 -> 3 -> 4.
333 * This case occurs when the load on C2 is deemed too high. So, instead of transitioning
334 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to
335 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
336 *
337 * c. 0 -> (3->2) -> 4.
338 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
339 * to enable the profiling to fully occur at level 0. In this case we change the compilation level
340 * of the method to 2 while the request is still in-queue, because it'll allow it to run much faster
341 * without full profiling while c2 is compiling.
342 *
343 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
344 * After a method was once compiled with C1 it can be identified as trivial and be compiled to
345 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
346 *
347 * e. 0 -> 4.
348 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
349 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
350 * the compiled version already exists).
351 *
352 * Note that since state 0 can be reached from any other state via deoptimization different loops
353 * are possible.
354 *
355 */
356
357 // Common transition function. Given a predicate determines if a method should transition to another level.
358 CompLevel AdvancedThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) {
359 CompLevel next_level = cur_level;
360 int i = method->invocation_count();
361 int b = method->backedge_count();
362
363 if (is_trivial(method)) {
364 next_level = CompLevel_simple;
365 } else {
366 switch(cur_level) {
367 case CompLevel_none:
368 // If we were at full profile level, would we switch to full opt?
369 if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) {
370 next_level = CompLevel_full_optimization;
371 } else if ((this->*p)(i, b, cur_level, method)) {
372 #if INCLUDE_JVMCI
373 if (UseJVMCICompiler) {
374 // Since JVMCI takes a while to warm up, its queue inevitably backs up during
375 // early VM execution.
376 next_level = CompLevel_full_profile;
377 break;
378 }
379 #endif
380 // C1-generated fully profiled code is about 30% slower than the limited profile
381 // code that has only invocation and backedge counters. The observation is that
382 // if C2 queue is large enough we can spend too much time in the fully profiled code
383 // while waiting for C2 to pick the method from the queue. To alleviate this problem
384 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
385 // we choose to compile a limited profiled version and then recompile with full profiling
386 // when the load on C2 goes down.
387 if (!disable_feedback && CompileBroker::queue_size(CompLevel_full_optimization) >
388 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
389 next_level = CompLevel_limited_profile;
390 } else {
391 next_level = CompLevel_full_profile;
392 }
393 }
394 break;
395 case CompLevel_limited_profile:
396 if (is_method_profiled(method)) {
397 // Special case: we got here because this method was fully profiled in the interpreter.
398 next_level = CompLevel_full_optimization;
399 } else {
400 MethodData* mdo = method->method_data();
401 if (mdo != NULL) {
402 if (mdo->would_profile()) {
403 if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=
404 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
405 (this->*p)(i, b, cur_level, method))) {
406 next_level = CompLevel_full_profile;
407 }
408 } else {
409 next_level = CompLevel_full_optimization;
410 }
411 }
412 }
413 break;
414 case CompLevel_full_profile:
415 {
416 MethodData* mdo = method->method_data();
417 if (mdo != NULL) {
418 if (mdo->would_profile()) {
419 int mdo_i = mdo->invocation_count_delta();
420 int mdo_b = mdo->backedge_count_delta();
421 if ((this->*p)(mdo_i, mdo_b, cur_level, method)) {
422 next_level = CompLevel_full_optimization;
423 }
424 } else {
425 next_level = CompLevel_full_optimization;
426 }
427 }
428 }
429 break;
430 }
431 }
432 return MIN2(next_level, (CompLevel)TieredStopAtLevel);
433 }
434
435 // Determine if a method should be compiled with a normal entry point at a different level.
436 CompLevel AdvancedThresholdPolicy::call_event(Method* method, CompLevel cur_level) {
437 CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(),
438 common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true));
439 CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);
440
441 // If OSR method level is greater than the regular method level, the levels should be
442 // equalized by raising the regular method level in order to avoid OSRs during each
443 // invocation of the method.
444 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
445 MethodData* mdo = method->method_data();
446 guarantee(mdo != NULL, "MDO should not be NULL");
447 if (mdo->invocation_count() >= 1) {
448 next_level = CompLevel_full_optimization;
449 }
450 } else {
451 next_level = MAX2(osr_level, next_level);
452 }
453 return next_level;
454 }
455
456 // Determine if we should do an OSR compilation of a given method.
457 CompLevel AdvancedThresholdPolicy::loop_event(Method* method, CompLevel cur_level) {
458 CompLevel next_level = common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true);
459 if (cur_level == CompLevel_none) {
460 // If there is a live OSR method that means that we deopted to the interpreter
461 // for the transition.
462 CompLevel osr_level = MIN2((CompLevel)method->highest_osr_comp_level(), next_level);
463 if (osr_level > CompLevel_none) {
464 return osr_level;
465 }
466 }
467 return next_level;
468 }
469
470 // Update the rate and submit compile
471 void AdvancedThresholdPolicy::submit_compile(const methodHandle& mh, int bci, CompLevel level, JavaThread* thread) {
472 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
473 update_rate(os::javaTimeMillis(), mh());
474 CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", thread);
475 }
476
477 // Handle the invocation event.
478 void AdvancedThresholdPolicy::method_invocation_event(const methodHandle& mh, const methodHandle& imh,
479 CompLevel level, nmethod* nm, JavaThread* thread) {
480 if (should_create_mdo(mh(), level)) {
481 create_mdo(mh, thread);
482 }
483 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh)) {
484 CompLevel next_level = call_event(mh(), level);
485 if (next_level != level) {
486 compile(mh, InvocationEntryBci, next_level, thread);
487 }
488 }
489 }
490
491 // Handle the back branch event. Notice that we can compile the method
492 // with a regular entry from here.
493 void AdvancedThresholdPolicy::method_back_branch_event(const methodHandle& mh, const methodHandle& imh,
494 int bci, CompLevel level, nmethod* nm, JavaThread* thread) {
495 if (should_create_mdo(mh(), level)) {
496 create_mdo(mh, thread);
497 }
498 // Check if MDO should be created for the inlined method
499 if (should_create_mdo(imh(), level)) {
500 create_mdo(imh, thread);
501 }
502
503 if (is_compilation_enabled()) {
504 CompLevel next_osr_level = loop_event(imh(), level);
505 CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level();
506 // At the very least compile the OSR version
507 if (!CompileBroker::compilation_is_in_queue(imh) && (next_osr_level != level)) {
508 compile(imh, bci, next_osr_level, thread);
509 }
510
511 // Use loop event as an opportunity to also check if there's been
512 // enough calls.
513 CompLevel cur_level, next_level;
514 if (mh() != imh()) { // If there is an enclosing method
515 guarantee(nm != NULL, "Should have nmethod here");
516 cur_level = comp_level(mh());
517 next_level = call_event(mh(), cur_level);
518
519 if (max_osr_level == CompLevel_full_optimization) {
520 // The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts
521 bool make_not_entrant = false;
522 if (nm->is_osr_method()) {
523 // This is an osr method, just make it not entrant and recompile later if needed
524 make_not_entrant = true;
525 } else {
526 if (next_level != CompLevel_full_optimization) {
527 // next_level is not full opt, so we need to recompile the
528 // enclosing method without the inlinee
529 cur_level = CompLevel_none;
530 make_not_entrant = true;
531 }
532 }
533 if (make_not_entrant) {
534 if (PrintTieredEvents) {
535 int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci;
536 print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level);
537 }
538 nm->make_not_entrant();
539 }
540 }
541 if (!CompileBroker::compilation_is_in_queue(mh)) {
542 // Fix up next_level if necessary to avoid deopts
543 if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) {
544 next_level = CompLevel_full_profile;
545 }
546 if (cur_level != next_level) {
547 compile(mh, InvocationEntryBci, next_level, thread);
548 }
549 }
550 } else {
551 cur_level = comp_level(imh());
552 next_level = call_event(imh(), cur_level);
553 if (!CompileBroker::compilation_is_in_queue(imh) && (next_level != cur_level)) {
554 compile(imh, InvocationEntryBci, next_level, thread);
555 }
556 }
557 }
558 }
559
560 #endif // TIERED