1 /*
2 * Copyright (c) 2010, 2019, 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_int(os::active_processor_count());
51 int loglog_cpu = log2_int(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 #if defined(X86) || defined(AARCH64)
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 (double)(method->rate() + 1) *
135 (method->invocation_count() + 1) * (method->backedge_count() + 1);
136 }
137
138 // Apply heuristics and return true if x should be compiled before y
139 bool AdvancedThresholdPolicy::compare_methods(Method* x, Method* y) {
140 if (x->highest_comp_level() > y->highest_comp_level()) {
141 // recompilation after deopt
142 return true;
143 } else
144 if (x->highest_comp_level() == y->highest_comp_level()) {
145 if (weight(x) > weight(y)) {
146 return true;
147 }
148 }
149 return false;
150 }
151
152 // Is method profiled enough?
153 bool AdvancedThresholdPolicy::is_method_profiled(Method* method) {
154 MethodData* mdo = method->method_data();
155 if (mdo != NULL) {
156 int i = mdo->invocation_count_delta();
157 int b = mdo->backedge_count_delta();
158 return call_predicate_helper<CompLevel_full_profile>(i, b, 1);
159 }
160 return false;
161 }
162
163 // Called with the queue locked and with at least one element
164 CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {
165 CompileTask *max_task = NULL;
166 Method* max_method = NULL;
167 jlong t = os::javaTimeMillis();
168 // Iterate through the queue and find a method with a maximum rate.
169 for (CompileTask* task = compile_queue->first(); task != NULL;) {
170 CompileTask* next_task = task->next();
171 Method* method = task->method();
172 update_rate(t, method);
173 if (max_task == NULL) {
174 max_task = task;
175 max_method = method;
176 } else {
177 // If a method has been stale for some time, remove it from the queue.
178 if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) {
179 if (PrintTieredEvents) {
180 print_event(REMOVE_FROM_QUEUE, method, method, task->osr_bci(), (CompLevel)task->comp_level());
181 }
182 compile_queue->remove_and_mark_stale(task);
183 method->clear_queued_for_compilation();
184 task = next_task;
185 continue;
186 }
187
188 // Select a method with a higher rate
189 if (compare_methods(method, max_method)) {
190 max_task = task;
191 max_method = method;
192 }
193 }
194 task = next_task;
195 }
196
197 if (max_task->comp_level() == CompLevel_full_profile && TieredStopAtLevel > CompLevel_full_profile
198 && is_method_profiled(max_method)) {
199
200 if (CompileBroker::compilation_is_complete(max_method, max_task->osr_bci(), CompLevel_limited_profile)) {
201 if (PrintTieredEvents) {
202 print_event(REMOVE_FROM_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
203 }
204 compile_queue->remove_and_mark_stale(max_task);
205 max_method->clear_queued_for_compilation();
206 return NULL;
207 }
208
209 max_task->set_comp_level(CompLevel_limited_profile);
210 if (PrintTieredEvents) {
211 print_event(UPDATE_IN_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
212 }
213 }
214
215 return max_task;
216 }
217
218 double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
219 double queue_size = CompileBroker::queue_size(level);
220 int comp_count = compiler_count(level);
221 double k = queue_size / (feedback_k * comp_count) + 1;
222
223 // Increase C1 compile threshold when the code cache is filled more
224 // than specified by IncreaseFirstTierCompileThresholdAt percentage.
225 // The main intention is to keep enough free space for C2 compiled code
226 // to achieve peak performance if the code cache is under stress.
227 if ((TieredStopAtLevel == CompLevel_full_optimization) && (level != CompLevel_full_optimization)) {
228 double current_reverse_free_ratio = CodeCache::reverse_free_ratio();
229 if (current_reverse_free_ratio > _increase_threshold_at_ratio) {
230 k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio);
231 }
232 }
233 return k;
234 }
235
236 // Call and loop predicates determine whether a transition to a higher
237 // compilation level should be performed (pointers to predicate functions
238 // are passed to common()).
239 // Tier?LoadFeedback is basically a coefficient that determines of
240 // how many methods per compiler thread can be in the queue before
241 // the threshold values double.
242 bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level) {
243 switch(cur_level) {
244 case CompLevel_none:
245 case CompLevel_limited_profile: {
246 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
247 return loop_predicate_helper<CompLevel_none>(i, b, k);
248 }
249 case CompLevel_full_profile: {
250 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
251 return loop_predicate_helper<CompLevel_full_profile>(i, b, k);
252 }
253 default:
254 return true;
255 }
256 }
257
258 bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level) {
259 switch(cur_level) {
260 case CompLevel_none:
261 case CompLevel_limited_profile: {
262 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
263 return call_predicate_helper<CompLevel_none>(i, b, k);
264 }
265 case CompLevel_full_profile: {
266 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
267 return call_predicate_helper<CompLevel_full_profile>(i, b, k);
268 }
269 default:
270 return true;
271 }
272 }
273
274 // If a method is old enough and is still in the interpreter we would want to
275 // start profiling without waiting for the compiled method to arrive.
276 // We also take the load on compilers into the account.
277 bool AdvancedThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) {
278 if (cur_level == CompLevel_none &&
279 CompileBroker::queue_size(CompLevel_full_optimization) <=
280 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
281 int i = method->invocation_count();
282 int b = method->backedge_count();
283 double k = Tier0ProfilingStartPercentage / 100.0;
284 return call_predicate_helper<CompLevel_none>(i, b, k) || loop_predicate_helper<CompLevel_none>(i, b, k);
285 }
286 return false;
287 }
288
289 // Inlining control: if we're compiling a profiled method with C1 and the callee
290 // is known to have OSRed in a C2 version, don't inline it.
291 bool AdvancedThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) {
292 CompLevel comp_level = (CompLevel)env->comp_level();
293 if (comp_level == CompLevel_full_profile ||
294 comp_level == CompLevel_limited_profile) {
295 return callee->highest_osr_comp_level() == CompLevel_full_optimization;
296 }
297 return false;
298 }
299
300 // Create MDO if necessary.
301 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, JavaThread* THREAD) {
302 if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return;
303 if (mh->method_data() == NULL) {
304 Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR);
305 }
306 }
307
308
309 /*
310 * Method states:
311 * 0 - interpreter (CompLevel_none)
312 * 1 - pure C1 (CompLevel_simple)
313 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
314 * 3 - C1 with full profiling (CompLevel_full_profile)
315 * 4 - C2 (CompLevel_full_optimization)
316 *
317 * Common state transition patterns:
318 * a. 0 -> 3 -> 4.
319 * The most common path. But note that even in this straightforward case
320 * profiling can start at level 0 and finish at level 3.
321 *
322 * b. 0 -> 2 -> 3 -> 4.
323 * This case occures when the load on C2 is deemed too high. So, instead of transitioning
324 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to
325 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
326 *
327 * c. 0 -> (3->2) -> 4.
328 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
329 * to enable the profiling to fully occur at level 0. In this case we change the compilation level
330 * of the method to 2 while the request is still in-queue, because it'll allow it to run much faster
331 * without full profiling while c2 is compiling.
332 *
333 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
334 * After a method was once compiled with C1 it can be identified as trivial and be compiled to
335 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
336 *
337 * e. 0 -> 4.
338 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
339 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
340 * the compiled version already exists).
341 *
342 * Note that since state 0 can be reached from any other state via deoptimization different loops
343 * are possible.
344 *
345 */
346
347 // Common transition function. Given a predicate determines if a method should transition to another level.
348 CompLevel AdvancedThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) {
349 CompLevel next_level = cur_level;
350 int i = method->invocation_count();
351 int b = method->backedge_count();
352
353 if (is_trivial(method)) {
354 next_level = CompLevel_simple;
355 } else {
356 switch(cur_level) {
357 case CompLevel_none:
358 // If we were at full profile level, would we switch to full opt?
359 if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) {
360 next_level = CompLevel_full_optimization;
361 } else if ((this->*p)(i, b, cur_level)) {
362 // C1-generated fully profiled code is about 30% slower than the limited profile
363 // code that has only invocation and backedge counters. The observation is that
364 // if C2 queue is large enough we can spend too much time in the fully profiled code
365 // while waiting for C2 to pick the method from the queue. To alleviate this problem
366 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
367 // we choose to compile a limited profiled version and then recompile with full profiling
368 // when the load on C2 goes down.
369 if (!disable_feedback && CompileBroker::queue_size(CompLevel_full_optimization) >
370 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
371 next_level = CompLevel_limited_profile;
372 } else {
373 next_level = CompLevel_full_profile;
374 }
375 }
376 break;
377 case CompLevel_limited_profile:
378 if (is_method_profiled(method)) {
379 // Special case: we got here because this method was fully profiled in the interpreter.
380 next_level = CompLevel_full_optimization;
381 } else {
382 MethodData* mdo = method->method_data();
383 if (mdo != NULL) {
384 if (mdo->would_profile()) {
385 if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=
386 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
387 (this->*p)(i, b, cur_level))) {
388 next_level = CompLevel_full_profile;
389 }
390 } else {
391 next_level = CompLevel_full_optimization;
392 }
393 }
394 }
395 break;
396 case CompLevel_full_profile:
397 {
398 MethodData* mdo = method->method_data();
399 if (mdo != NULL) {
400 if (mdo->would_profile()) {
401 int mdo_i = mdo->invocation_count_delta();
402 int mdo_b = mdo->backedge_count_delta();
403 if ((this->*p)(mdo_i, mdo_b, cur_level)) {
404 next_level = CompLevel_full_optimization;
405 }
406 } else {
407 next_level = CompLevel_full_optimization;
408 }
409 }
410 }
411 break;
412 }
413 }
414 return MIN2(next_level, (CompLevel)TieredStopAtLevel);
415 }
416
417 // Determine if a method should be compiled with a normal entry point at a different level.
418 CompLevel AdvancedThresholdPolicy::call_event(Method* method, CompLevel cur_level) {
419 CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(),
420 common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true));
421 CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);
422
423 // If OSR method level is greater than the regular method level, the levels should be
424 // equalized by raising the regular method level in order to avoid OSRs during each
425 // invocation of the method.
426 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
427 MethodData* mdo = method->method_data();
428 guarantee(mdo != NULL, "MDO should not be NULL");
429 if (mdo->invocation_count() >= 1) {
430 next_level = CompLevel_full_optimization;
431 }
432 } else {
433 next_level = MAX2(osr_level, next_level);
434 }
435 return next_level;
436 }
437
438 // Determine if we should do an OSR compilation of a given method.
439 CompLevel AdvancedThresholdPolicy::loop_event(Method* method, CompLevel cur_level) {
440 CompLevel next_level = common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true);
441 if (cur_level == CompLevel_none) {
442 // If there is a live OSR method that means that we deopted to the interpreter
443 // for the transition.
444 CompLevel osr_level = MIN2((CompLevel)method->highest_osr_comp_level(), next_level);
445 if (osr_level > CompLevel_none) {
446 return osr_level;
447 }
448 }
449 return next_level;
450 }
451
452 // Update the rate and submit compile
453 void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, JavaThread* thread) {
454 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
455 update_rate(os::javaTimeMillis(), mh());
456 CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", thread);
457 }
458
459 // Handle the invocation event.
460 void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh,
461 CompLevel level, nmethod* nm, JavaThread* thread) {
462 if (should_create_mdo(mh(), level)) {
463 create_mdo(mh, thread);
464 }
465 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh)) {
466 CompLevel next_level = call_event(mh(), level);
467 if (next_level != level) {
468 compile(mh, InvocationEntryBci, next_level, thread);
469 }
470 }
471 }
472
473 // Handle the back branch event. Notice that we can compile the method
474 // with a regular entry from here.
475 void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh,
476 int bci, CompLevel level, nmethod* nm, JavaThread* thread) {
477 if (should_create_mdo(mh(), level)) {
478 create_mdo(mh, thread);
479 }
480 // Check if MDO should be created for the inlined method
481 if (should_create_mdo(imh(), level)) {
482 create_mdo(imh, thread);
483 }
484
485 if (is_compilation_enabled()) {
486 CompLevel next_osr_level = loop_event(imh(), level);
487 CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level();
488 // At the very least compile the OSR version
489 if (!CompileBroker::compilation_is_in_queue(imh) && (next_osr_level != level)) {
490 compile(imh, bci, next_osr_level, thread);
491 }
492
493 // Use loop event as an opportunity to also check if there's been
494 // enough calls.
495 CompLevel cur_level, next_level;
496 if (mh() != imh()) { // If there is an enclosing method
497 guarantee(nm != NULL, "Should have nmethod here");
498 cur_level = comp_level(mh());
499 next_level = call_event(mh(), cur_level);
500
501 if (max_osr_level == CompLevel_full_optimization) {
502 // The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts
503 bool make_not_entrant = false;
504 if (nm->is_osr_method()) {
505 // This is an osr method, just make it not entrant and recompile later if needed
506 make_not_entrant = true;
507 } else {
508 if (next_level != CompLevel_full_optimization) {
509 // next_level is not full opt, so we need to recompile the
510 // enclosing method without the inlinee
511 cur_level = CompLevel_none;
512 make_not_entrant = true;
513 }
514 }
515 if (make_not_entrant) {
516 if (PrintTieredEvents) {
517 int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci;
518 print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level);
519 }
520 nm->make_not_entrant();
521 }
522 }
523 if (!CompileBroker::compilation_is_in_queue(mh)) {
524 // Fix up next_level if necessary to avoid deopts
525 if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) {
526 next_level = CompLevel_full_profile;
527 }
528 if (cur_level != next_level) {
529 compile(mh, InvocationEntryBci, next_level, thread);
530 }
531 }
532 } else {
533 cur_level = comp_level(imh());
534 next_level = call_event(imh(), cur_level);
535 if (!CompileBroker::compilation_is_in_queue(imh) && (next_level != cur_level)) {
536 compile(imh, InvocationEntryBci, next_level, thread);
537 }
538 }
539 }
540 }
541
542 #endif // TIERED