Wed, 03 Jul 2019 20:42:37 +0800
Merge
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 */
25 #include "precompiled.hpp"
26 #include "runtime/advancedThresholdPolicy.hpp"
27 #include "runtime/simpleThresholdPolicy.inline.hpp"
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());
37 tty->print(" k=%.2lf,%.2lf", threshold_scale(CompLevel_full_profile, Tier3LoadFeedback),
38 threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));
40 }
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 }
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());
59 // Some inlining tuning
60 #ifdef X86
61 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
62 FLAG_SET_DEFAULT(InlineSmallCode, 2000);
63 }
64 #endif
66 #ifdef SPARC
67 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
68 FLAG_SET_DEFAULT(InlineSmallCode, 2500);
69 }
70 #endif
72 set_increase_threshold_at_ratio();
73 set_start_time(os::javaTimeMillis());
74 }
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;
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 }
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();
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 }
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 }
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 }
133 double AdvancedThresholdPolicy::weight(Method* method) {
134 return (double)(method->rate() + 1) *
135 (method->invocation_count() + 1) * (method->backedge_count() + 1);
136 }
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 }
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 }
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 }
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 }
197 if (max_task->comp_level() == CompLevel_full_profile && TieredStopAtLevel > CompLevel_full_profile
198 && is_method_profiled(max_method)) {
199 max_task->set_comp_level(CompLevel_limited_profile);
200 if (PrintTieredEvents) {
201 print_event(UPDATE_IN_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
202 }
203 }
205 return max_task;
206 }
208 double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
209 double queue_size = CompileBroker::queue_size(level);
210 int comp_count = compiler_count(level);
211 double k = queue_size / (feedback_k * comp_count) + 1;
213 // Increase C1 compile threshold when the code cache is filled more
214 // than specified by IncreaseFirstTierCompileThresholdAt percentage.
215 // The main intention is to keep enough free space for C2 compiled code
216 // to achieve peak performance if the code cache is under stress.
217 if ((TieredStopAtLevel == CompLevel_full_optimization) && (level != CompLevel_full_optimization)) {
218 double current_reverse_free_ratio = CodeCache::reverse_free_ratio();
219 if (current_reverse_free_ratio > _increase_threshold_at_ratio) {
220 k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio);
221 }
222 }
223 return k;
224 }
226 // Call and loop predicates determine whether a transition to a higher
227 // compilation level should be performed (pointers to predicate functions
228 // are passed to common()).
229 // Tier?LoadFeedback is basically a coefficient that determines of
230 // how many methods per compiler thread can be in the queue before
231 // the threshold values double.
232 bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level) {
233 switch(cur_level) {
234 case CompLevel_none:
235 case CompLevel_limited_profile: {
236 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
237 return loop_predicate_helper<CompLevel_none>(i, b, k);
238 }
239 case CompLevel_full_profile: {
240 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
241 return loop_predicate_helper<CompLevel_full_profile>(i, b, k);
242 }
243 default:
244 return true;
245 }
246 }
248 bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level) {
249 switch(cur_level) {
250 case CompLevel_none:
251 case CompLevel_limited_profile: {
252 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
253 return call_predicate_helper<CompLevel_none>(i, b, k);
254 }
255 case CompLevel_full_profile: {
256 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
257 return call_predicate_helper<CompLevel_full_profile>(i, b, k);
258 }
259 default:
260 return true;
261 }
262 }
264 // If a method is old enough and is still in the interpreter we would want to
265 // start profiling without waiting for the compiled method to arrive.
266 // We also take the load on compilers into the account.
267 bool AdvancedThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) {
268 if (cur_level == CompLevel_none &&
269 CompileBroker::queue_size(CompLevel_full_optimization) <=
270 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
271 int i = method->invocation_count();
272 int b = method->backedge_count();
273 double k = Tier0ProfilingStartPercentage / 100.0;
274 return call_predicate_helper<CompLevel_none>(i, b, k) || loop_predicate_helper<CompLevel_none>(i, b, k);
275 }
276 return false;
277 }
279 // Inlining control: if we're compiling a profiled method with C1 and the callee
280 // is known to have OSRed in a C2 version, don't inline it.
281 bool AdvancedThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) {
282 CompLevel comp_level = (CompLevel)env->comp_level();
283 if (comp_level == CompLevel_full_profile ||
284 comp_level == CompLevel_limited_profile) {
285 return callee->highest_osr_comp_level() == CompLevel_full_optimization;
286 }
287 return false;
288 }
290 // Create MDO if necessary.
291 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, JavaThread* THREAD) {
292 if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return;
293 if (mh->method_data() == NULL) {
294 Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR);
295 }
296 }
299 /*
300 * Method states:
301 * 0 - interpreter (CompLevel_none)
302 * 1 - pure C1 (CompLevel_simple)
303 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
304 * 3 - C1 with full profiling (CompLevel_full_profile)
305 * 4 - C2 (CompLevel_full_optimization)
306 *
307 * Common state transition patterns:
308 * a. 0 -> 3 -> 4.
309 * The most common path. But note that even in this straightforward case
310 * profiling can start at level 0 and finish at level 3.
311 *
312 * b. 0 -> 2 -> 3 -> 4.
313 * This case occures when the load on C2 is deemed too high. So, instead of transitioning
314 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to
315 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
316 *
317 * c. 0 -> (3->2) -> 4.
318 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
319 * to enable the profiling to fully occur at level 0. In this case we change the compilation level
320 * of the method to 2 while the request is still in-queue, because it'll allow it to run much faster
321 * without full profiling while c2 is compiling.
322 *
323 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
324 * After a method was once compiled with C1 it can be identified as trivial and be compiled to
325 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
326 *
327 * e. 0 -> 4.
328 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
329 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
330 * the compiled version already exists).
331 *
332 * Note that since state 0 can be reached from any other state via deoptimization different loops
333 * are possible.
334 *
335 */
337 // Common transition function. Given a predicate determines if a method should transition to another level.
338 CompLevel AdvancedThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) {
339 CompLevel next_level = cur_level;
340 int i = method->invocation_count();
341 int b = method->backedge_count();
343 if (is_trivial(method)) {
344 next_level = CompLevel_simple;
345 } else {
346 switch(cur_level) {
347 case CompLevel_none:
348 // If we were at full profile level, would we switch to full opt?
349 if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) {
350 next_level = CompLevel_full_optimization;
351 } else if ((this->*p)(i, b, cur_level)) {
352 // C1-generated fully profiled code is about 30% slower than the limited profile
353 // code that has only invocation and backedge counters. The observation is that
354 // if C2 queue is large enough we can spend too much time in the fully profiled code
355 // while waiting for C2 to pick the method from the queue. To alleviate this problem
356 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
357 // we choose to compile a limited profiled version and then recompile with full profiling
358 // when the load on C2 goes down.
359 if (!disable_feedback && CompileBroker::queue_size(CompLevel_full_optimization) >
360 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
361 next_level = CompLevel_limited_profile;
362 } else {
363 next_level = CompLevel_full_profile;
364 }
365 }
366 break;
367 case CompLevel_limited_profile:
368 if (is_method_profiled(method)) {
369 // Special case: we got here because this method was fully profiled in the interpreter.
370 next_level = CompLevel_full_optimization;
371 } else {
372 MethodData* mdo = method->method_data();
373 if (mdo != NULL) {
374 if (mdo->would_profile()) {
375 if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=
376 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
377 (this->*p)(i, b, cur_level))) {
378 next_level = CompLevel_full_profile;
379 }
380 } else {
381 next_level = CompLevel_full_optimization;
382 }
383 }
384 }
385 break;
386 case CompLevel_full_profile:
387 {
388 MethodData* mdo = method->method_data();
389 if (mdo != NULL) {
390 if (mdo->would_profile()) {
391 int mdo_i = mdo->invocation_count_delta();
392 int mdo_b = mdo->backedge_count_delta();
393 if ((this->*p)(mdo_i, mdo_b, cur_level)) {
394 next_level = CompLevel_full_optimization;
395 }
396 } else {
397 next_level = CompLevel_full_optimization;
398 }
399 }
400 }
401 break;
402 }
403 }
404 return MIN2(next_level, (CompLevel)TieredStopAtLevel);
405 }
407 // Determine if a method should be compiled with a normal entry point at a different level.
408 CompLevel AdvancedThresholdPolicy::call_event(Method* method, CompLevel cur_level) {
409 CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(),
410 common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true));
411 CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);
413 // If OSR method level is greater than the regular method level, the levels should be
414 // equalized by raising the regular method level in order to avoid OSRs during each
415 // invocation of the method.
416 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
417 MethodData* mdo = method->method_data();
418 guarantee(mdo != NULL, "MDO should not be NULL");
419 if (mdo->invocation_count() >= 1) {
420 next_level = CompLevel_full_optimization;
421 }
422 } else {
423 next_level = MAX2(osr_level, next_level);
424 }
425 return next_level;
426 }
428 // Determine if we should do an OSR compilation of a given method.
429 CompLevel AdvancedThresholdPolicy::loop_event(Method* method, CompLevel cur_level) {
430 CompLevel next_level = common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true);
431 if (cur_level == CompLevel_none) {
432 // If there is a live OSR method that means that we deopted to the interpreter
433 // for the transition.
434 CompLevel osr_level = MIN2((CompLevel)method->highest_osr_comp_level(), next_level);
435 if (osr_level > CompLevel_none) {
436 return osr_level;
437 }
438 }
439 return next_level;
440 }
442 // Update the rate and submit compile
443 void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, JavaThread* thread) {
444 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
445 update_rate(os::javaTimeMillis(), mh());
446 CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", thread);
447 }
449 // Handle the invocation event.
450 void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh,
451 CompLevel level, nmethod* nm, JavaThread* thread) {
452 if (should_create_mdo(mh(), level)) {
453 create_mdo(mh, thread);
454 }
455 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh)) {
456 CompLevel next_level = call_event(mh(), level);
457 if (next_level != level) {
458 compile(mh, InvocationEntryBci, next_level, thread);
459 }
460 }
461 }
463 // Handle the back branch event. Notice that we can compile the method
464 // with a regular entry from here.
465 void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh,
466 int bci, CompLevel level, nmethod* nm, JavaThread* thread) {
467 if (should_create_mdo(mh(), level)) {
468 create_mdo(mh, thread);
469 }
470 // Check if MDO should be created for the inlined method
471 if (should_create_mdo(imh(), level)) {
472 create_mdo(imh, thread);
473 }
475 if (is_compilation_enabled()) {
476 CompLevel next_osr_level = loop_event(imh(), level);
477 CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level();
478 // At the very least compile the OSR version
479 if (!CompileBroker::compilation_is_in_queue(imh) && (next_osr_level != level)) {
480 compile(imh, bci, next_osr_level, thread);
481 }
483 // Use loop event as an opportunity to also check if there's been
484 // enough calls.
485 CompLevel cur_level, next_level;
486 if (mh() != imh()) { // If there is an enclosing method
487 guarantee(nm != NULL, "Should have nmethod here");
488 cur_level = comp_level(mh());
489 next_level = call_event(mh(), cur_level);
491 if (max_osr_level == CompLevel_full_optimization) {
492 // The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts
493 bool make_not_entrant = false;
494 if (nm->is_osr_method()) {
495 // This is an osr method, just make it not entrant and recompile later if needed
496 make_not_entrant = true;
497 } else {
498 if (next_level != CompLevel_full_optimization) {
499 // next_level is not full opt, so we need to recompile the
500 // enclosing method without the inlinee
501 cur_level = CompLevel_none;
502 make_not_entrant = true;
503 }
504 }
505 if (make_not_entrant) {
506 if (PrintTieredEvents) {
507 int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci;
508 print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level);
509 }
510 nm->make_not_entrant();
511 }
512 }
513 if (!CompileBroker::compilation_is_in_queue(mh)) {
514 // Fix up next_level if necessary to avoid deopts
515 if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) {
516 next_level = CompLevel_full_profile;
517 }
518 if (cur_level != next_level) {
519 compile(mh, InvocationEntryBci, next_level, thread);
520 }
521 }
522 } else {
523 cur_level = comp_level(imh());
524 next_level = call_event(imh(), cur_level);
525 if (!CompileBroker::compilation_is_in_queue(imh) && (next_level != cur_level)) {
526 compile(imh, InvocationEntryBci, next_level, thread);
527 }
528 }
529 }
530 }
532 #endif // TIERED