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 (method->rate() + 1) * ((method->invocation_count() + 1) * (method->backedge_count() + 1));
137 }
138
139 // Apply heuristics and return true if x should be compiled before y
140 bool AdvancedThresholdPolicy::compare_methods(Method* x, Method* y) {
141 if (x->highest_comp_level() > y->highest_comp_level()) {
142 // recompilation after deopt
143 return true;
144 } else
145 if (x->highest_comp_level() == y->highest_comp_level()) {
146 if (weight(x) > weight(y)) {
147 return true;
148 }
149 }
150 return false;
151 }
152
153 // Is method profiled enough?
154 bool AdvancedThresholdPolicy::is_method_profiled(Method* method) {
155 MethodData* mdo = method->method_data();
156 if (mdo != NULL) {
157 int i = mdo->invocation_count_delta();
158 int b = mdo->backedge_count_delta();
159 return call_predicate_helper<CompLevel_full_profile>(i, b, 1, method);
160 }
161 return false;
162 }
163
164 // Called with the queue locked and with at least one element
165 CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {
166 #if INCLUDE_JVMCI
167 CompileTask *max_non_jvmci_task = NULL;
168 #endif
169 CompileTask *max_task = NULL;
170 Method* max_method = NULL;
171 jlong t = os::javaTimeMillis();
172 // Iterate through the queue and find a method with a maximum rate.
173 for (CompileTask* task = compile_queue->first(); task != NULL;) {
174 CompileTask* next_task = task->next();
175 Method* method = task->method();
176 update_rate(t, method);
177 if (max_task == NULL) {
178 max_task = task;
179 max_method = method;
180 } else {
181 // If a method has been stale for some time, remove it from the queue.
182 if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) {
183 if (PrintTieredEvents) {
184 print_event(REMOVE_FROM_QUEUE, method, method, task->osr_bci(), (CompLevel)task->comp_level());
185 }
186 task->log_task_dequeued("stale");
187 compile_queue->remove_and_mark_stale(task);
188 method->clear_queued_for_compilation();
189 task = next_task;
190 continue;
191 }
192
193 // Select a method with a higher rate
194 if (compare_methods(method, max_method)) {
195 max_task = task;
196 max_method = method;
197 }
198 }
199 task = next_task;
200 }
201
202 #if INCLUDE_JVMCI
203 if (UseJVMCICompiler) {
204 if (max_non_jvmci_task != NULL) {
205 max_task = max_non_jvmci_task;
206 max_method = max_task->method();
207 }
208 }
209 #endif
210
211 if (max_task->comp_level() == CompLevel_full_profile && TieredStopAtLevel > CompLevel_full_profile
212 && is_method_profiled(max_method)) {
213 max_task->set_comp_level(CompLevel_limited_profile);
214 if (PrintTieredEvents) {
215 print_event(UPDATE_IN_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
216 }
217 }
218
219 return max_task;
220 }
221
222 double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
223 double queue_size = CompileBroker::queue_size(level);
224 int comp_count = compiler_count(level);
225 double k = queue_size / (feedback_k * comp_count) + 1;
226
227 // Increase C1 compile threshold when the code cache is filled more
228 // than specified by IncreaseFirstTierCompileThresholdAt percentage.
229 // The main intention is to keep enough free space for C2 compiled code
230 // to achieve peak performance if the code cache is under stress.
231 if ((TieredStopAtLevel == CompLevel_full_optimization) && (level != CompLevel_full_optimization)) {
232 double current_reverse_free_ratio = CodeCache::reverse_free_ratio(CodeCache::get_code_blob_type(level));
233 if (current_reverse_free_ratio > _increase_threshold_at_ratio) {
234 k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio);
235 }
236 }
237 return k;
238 }
239
240 // Call and loop predicates determine whether a transition to a higher
241 // compilation level should be performed (pointers to predicate functions
242 // are passed to common()).
243 // Tier?LoadFeedback is basically a coefficient that determines of
244 // how many methods per compiler thread can be in the queue before
245 // the threshold values double.
246 bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level, Method* method) {
247 switch(cur_level) {
248 case CompLevel_none:
249 case CompLevel_limited_profile: {
250 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
251 return loop_predicate_helper<CompLevel_none>(i, b, k, method);
252 }
253 case CompLevel_full_profile: {
254 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
255 return loop_predicate_helper<CompLevel_full_profile>(i, b, k, method);
256 }
257 default:
258 return true;
259 }
260 }
261
262 bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level, Method* method) {
263 switch(cur_level) {
264 case CompLevel_none:
265 case CompLevel_limited_profile: {
266 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
267 return call_predicate_helper<CompLevel_none>(i, b, k, method);
268 }
269 case CompLevel_full_profile: {
270 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
271 return call_predicate_helper<CompLevel_full_profile>(i, b, k, method);
272 }
273 default:
274 return true;
275 }
276 }
277
278 // If a method is old enough and is still in the interpreter we would want to
279 // start profiling without waiting for the compiled method to arrive.
280 // We also take the load on compilers into the account.
281 bool AdvancedThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) {
282 if (cur_level == CompLevel_none &&
283 CompileBroker::queue_size(CompLevel_full_optimization) <=
284 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
285 int i = method->invocation_count();
286 int b = method->backedge_count();
287 double k = Tier0ProfilingStartPercentage / 100.0;
288 return call_predicate_helper<CompLevel_none>(i, b, k, method) || loop_predicate_helper<CompLevel_none>(i, b, k, method);
289 }
290 return false;
291 }
292
293 // Inlining control: if we're compiling a profiled method with C1 and the callee
294 // is known to have OSRed in a C2 version, don't inline it.
295 bool AdvancedThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) {
296 CompLevel comp_level = (CompLevel)env->comp_level();
297 if (comp_level == CompLevel_full_profile ||
298 comp_level == CompLevel_limited_profile) {
299 return callee->highest_osr_comp_level() == CompLevel_full_optimization;
300 }
301 return false;
302 }
303
304 // Create MDO if necessary.
305 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, JavaThread* THREAD) {
306 if (mh->is_native() ||
307 mh->is_abstract() ||
308 mh->is_accessor() ||
309 mh->is_constant_getter()) {
310 return;
311 }
312 if (mh->method_data() == NULL) {
313 Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR);
314 }
315 }
316
317
318 /*
319 * Method states:
320 * 0 - interpreter (CompLevel_none)
321 * 1 - pure C1 (CompLevel_simple)
322 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
323 * 3 - C1 with full profiling (CompLevel_full_profile)
324 * 4 - C2 (CompLevel_full_optimization)
325 *
326 * Common state transition patterns:
327 * a. 0 -> 3 -> 4.
328 * The most common path. But note that even in this straightforward case
329 * profiling can start at level 0 and finish at level 3.
330 *
331 * b. 0 -> 2 -> 3 -> 4.
332 * This case occurs when the load on C2 is deemed too high. So, instead of transitioning
333 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to
334 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
335 *
336 * c. 0 -> (3->2) -> 4.
337 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
338 * to enable the profiling to fully occur at level 0. In this case we change the compilation level
339 * of the method to 2 while the request is still in-queue, because it'll allow it to run much faster
340 * without full profiling while c2 is compiling.
341 *
342 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
343 * After a method was once compiled with C1 it can be identified as trivial and be compiled to
344 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
345 *
346 * e. 0 -> 4.
347 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
348 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
349 * the compiled version already exists).
350 *
351 * Note that since state 0 can be reached from any other state via deoptimization different loops
352 * are possible.
353 *
354 */
355
356 // Common transition function. Given a predicate determines if a method should transition to another level.
357 CompLevel AdvancedThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) {
358 CompLevel next_level = cur_level;
359 int i = method->invocation_count();
360 int b = method->backedge_count();
361
362 if (is_trivial(method)) {
363 next_level = CompLevel_simple;
364 } else {
365 switch(cur_level) {
366 case CompLevel_none:
367 // If we were at full profile level, would we switch to full opt?
368 if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) {
369 next_level = CompLevel_full_optimization;
370 } else if ((this->*p)(i, b, cur_level, method)) {
371 #if INCLUDE_JVMCI
372 if (UseJVMCICompiler) {
373 // Since JVMCI takes a while to warm up, its queue inevitably backs up during
374 // early VM execution.
375 next_level = CompLevel_full_profile;
376 break;
377 }
378 #endif
379 // C1-generated fully profiled code is about 30% slower than the limited profile
380 // code that has only invocation and backedge counters. The observation is that
381 // if C2 queue is large enough we can spend too much time in the fully profiled code
382 // while waiting for C2 to pick the method from the queue. To alleviate this problem
383 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
384 // we choose to compile a limited profiled version and then recompile with full profiling
385 // when the load on C2 goes down.
386 if (!disable_feedback && CompileBroker::queue_size(CompLevel_full_optimization) >
387 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
388 next_level = CompLevel_limited_profile;
389 } else {
390 next_level = CompLevel_full_profile;
391 }
392 }
393 break;
394 case CompLevel_limited_profile:
395 if (is_method_profiled(method)) {
396 // Special case: we got here because this method was fully profiled in the interpreter.
397 next_level = CompLevel_full_optimization;
398 } else {
399 MethodData* mdo = method->method_data();
400 if (mdo != NULL) {
401 if (mdo->would_profile()) {
402 if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=
403 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
404 (this->*p)(i, b, cur_level, method))) {
405 next_level = CompLevel_full_profile;
406 }
407 } else {
408 next_level = CompLevel_full_optimization;
409 }
410 }
411 }
412 break;
413 case CompLevel_full_profile:
414 {
415 MethodData* mdo = method->method_data();
416 if (mdo != NULL) {
417 if (mdo->would_profile()) {
418 int mdo_i = mdo->invocation_count_delta();
419 int mdo_b = mdo->backedge_count_delta();
420 if ((this->*p)(mdo_i, mdo_b, cur_level, method)) {
421 next_level = CompLevel_full_optimization;
422 }
423 } else {
424 next_level = CompLevel_full_optimization;
425 }
426 }
427 }
428 break;
429 }
430 }
431 return MIN2(next_level, (CompLevel)TieredStopAtLevel);
432 }
433
434 // Determine if a method should be compiled with a normal entry point at a different level.
435 CompLevel AdvancedThresholdPolicy::call_event(Method* method, CompLevel cur_level) {
436 CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(),
437 common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true));
438 CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);
439
440 // If OSR method level is greater than the regular method level, the levels should be
441 // equalized by raising the regular method level in order to avoid OSRs during each
442 // invocation of the method.
443 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
444 MethodData* mdo = method->method_data();
445 guarantee(mdo != NULL, "MDO should not be NULL");
446 if (mdo->invocation_count() >= 1) {
447 next_level = CompLevel_full_optimization;
448 }
449 } else {
450 next_level = MAX2(osr_level, next_level);
451 }
452 return next_level;
453 }
454
455 // Determine if we should do an OSR compilation of a given method.
456 CompLevel AdvancedThresholdPolicy::loop_event(Method* method, CompLevel cur_level) {
457 CompLevel next_level = common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true);
458 if (cur_level == CompLevel_none) {
459 // If there is a live OSR method that means that we deopted to the interpreter
460 // for the transition.
461 CompLevel osr_level = MIN2((CompLevel)method->highest_osr_comp_level(), next_level);
462 if (osr_level > CompLevel_none) {
463 return osr_level;
464 }
465 }
466 return next_level;
467 }
468
469 // Update the rate and submit compile
470 void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, JavaThread* thread) {
471 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
472 update_rate(os::javaTimeMillis(), mh());
473 CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", thread);
474 }
475
476 // Handle the invocation event.
477 void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh,
478 CompLevel level, nmethod* nm, JavaThread* thread) {
479 if (should_create_mdo(mh(), level)) {
480 create_mdo(mh, thread);
481 }
482 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh)) {
483 CompLevel next_level = call_event(mh(), level);
484 if (next_level != level) {
485 compile(mh, InvocationEntryBci, next_level, thread);
486 }
487 }
488 }
489
490 // Handle the back branch event. Notice that we can compile the method
491 // with a regular entry from here.
492 void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh,
493 int bci, CompLevel level, nmethod* nm, JavaThread* thread) {
494 if (should_create_mdo(mh(), level)) {
495 create_mdo(mh, thread);
496 }
497 // Check if MDO should be created for the inlined method
498 if (should_create_mdo(imh(), level)) {
499 create_mdo(imh, thread);
500 }
501
502 if (is_compilation_enabled()) {
503 CompLevel next_osr_level = loop_event(imh(), level);
504 CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level();
505 // At the very least compile the OSR version
506 if (!CompileBroker::compilation_is_in_queue(imh) && (next_osr_level != level)) {
507 compile(imh, bci, next_osr_level, thread);
508 }
509
510 // Use loop event as an opportunity to also check if there's been
511 // enough calls.
512 CompLevel cur_level, next_level;
513 if (mh() != imh()) { // If there is an enclosing method
514 guarantee(nm != NULL, "Should have nmethod here");
515 cur_level = comp_level(mh());
516 next_level = call_event(mh(), cur_level);
517
518 if (max_osr_level == CompLevel_full_optimization) {
519 // The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts
520 bool make_not_entrant = false;
521 if (nm->is_osr_method()) {
522 // This is an osr method, just make it not entrant and recompile later if needed
523 make_not_entrant = true;
524 } else {
525 if (next_level != CompLevel_full_optimization) {
526 // next_level is not full opt, so we need to recompile the
527 // enclosing method without the inlinee
528 cur_level = CompLevel_none;
529 make_not_entrant = true;
530 }
531 }
532 if (make_not_entrant) {
533 if (PrintTieredEvents) {
534 int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci;
535 print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level);
536 }
537 nm->make_not_entrant();
538 }
539 }
540 if (!CompileBroker::compilation_is_in_queue(mh)) {
541 // Fix up next_level if necessary to avoid deopts
542 if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) {
543 next_level = CompLevel_full_profile;
544 }
545 if (cur_level != next_level) {
546 compile(mh, InvocationEntryBci, next_level, thread);
547 }
548 }
549 } else {
550 cur_level = comp_level(imh());
551 next_level = call_event(imh(), cur_level);
552 if (!CompileBroker::compilation_is_in_queue(imh) && (next_level != cur_level)) {
553 compile(imh, InvocationEntryBci, next_level, thread);
554 }
555 }
556 }
557 }
558
559 #endif // TIERED