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