1 /*
2 * Copyright (c) 2010, 2011, 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 - count / 3, 1));
57
58 // Some inlining tuning
59 #ifdef X86
60 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
61 FLAG_SET_DEFAULT(InlineSmallCode, 2000);
62 }
63 #endif
64
65 #ifdef SPARC
66 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
67 FLAG_SET_DEFAULT(InlineSmallCode, 2500);
68 }
69 #endif
70
71
72 set_start_time(os::javaTimeMillis());
73 }
74
75 // update_rate() is called from select_task() while holding a compile queue lock.
76 void AdvancedThresholdPolicy::update_rate(jlong t, methodOop m) {
77 if (is_old(m)) {
78 // We don't remove old methods from the queue,
79 // so we can just zero the rate.
80 m->set_rate(0);
81 return;
82 }
83
84 // We don't update the rate if we've just came out of a safepoint.
85 // delta_s is the time since last safepoint in milliseconds.
86 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
87 jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement
88 // How many events were there since the last time?
89 int event_count = m->invocation_count() + m->backedge_count();
90 int delta_e = event_count - m->prev_event_count();
91
92 // We should be running for at least 1ms.
93 if (delta_s >= TieredRateUpdateMinTime) {
94 // And we must've taken the previous point at least 1ms before.
95 if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) {
96 m->set_prev_time(t);
97 m->set_prev_event_count(event_count);
98 m->set_rate((float)delta_e / (float)delta_t); // Rate is events per millisecond
99 } else
100 if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) {
101 // If nothing happened for 25ms, zero the rate. Don't modify prev values.
102 m->set_rate(0);
103 }
104 }
105 }
106
107 // Check if this method has been stale from a given number of milliseconds.
108 // See select_task().
109 bool AdvancedThresholdPolicy::is_stale(jlong t, jlong timeout, methodOop m) {
110 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
111 jlong delta_t = t - m->prev_time();
112 if (delta_t > timeout && delta_s > timeout) {
113 int event_count = m->invocation_count() + m->backedge_count();
114 int delta_e = event_count - m->prev_event_count();
115 // Return true if there were no events.
116 return delta_e == 0;
117 }
118 return false;
119 }
120
121 // We don't remove old methods from the compile queue even if they have
122 // very low activity. See select_task().
123 bool AdvancedThresholdPolicy::is_old(methodOop method) {
124 return method->invocation_count() > 50000 || method->backedge_count() > 500000;
125 }
126
127 double AdvancedThresholdPolicy::weight(methodOop method) {
128 return (method->rate() + 1) * ((method->invocation_count() + 1) * (method->backedge_count() + 1));
129 }
130
131 // Apply heuristics and return true if x should be compiled before y
132 bool AdvancedThresholdPolicy::compare_methods(methodOop x, methodOop y) {
133 if (x->highest_comp_level() > y->highest_comp_level()) {
134 // recompilation after deopt
135 return true;
136 } else
137 if (x->highest_comp_level() == y->highest_comp_level()) {
138 if (weight(x) > weight(y)) {
139 return true;
140 }
141 }
142 return false;
143 }
144
145 // Is method profiled enough?
146 bool AdvancedThresholdPolicy::is_method_profiled(methodOop method) {
147 methodDataOop mdo = method->method_data();
148 if (mdo != NULL) {
149 int i = mdo->invocation_count_delta();
150 int b = mdo->backedge_count_delta();
151 return call_predicate_helper<CompLevel_full_profile>(i, b, 1);
152 }
153 return false;
154 }
155
156 // Called with the queue locked and with at least one element
157 CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {
158 CompileTask *max_task = NULL;
159 methodOop max_method;
160 jlong t = os::javaTimeMillis();
161 // Iterate through the queue and find a method with a maximum rate.
162 for (CompileTask* task = compile_queue->first(); task != NULL;) {
163 CompileTask* next_task = task->next();
164 methodOop method = (methodOop)JNIHandles::resolve(task->method_handle());
165 methodDataOop mdo = method->method_data();
166 update_rate(t, method);
167 if (max_task == NULL) {
168 max_task = task;
169 max_method = method;
170 } else {
171 // If a method has been stale for some time, remove it from the queue.
172 if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) {
173 if (PrintTieredEvents) {
174 print_event(REMOVE_FROM_QUEUE, method, method, task->osr_bci(), (CompLevel)task->comp_level());
175 }
176 CompileTaskWrapper ctw(task); // Frees the task
177 compile_queue->remove(task);
178 method->clear_queued_for_compilation();
179 task = next_task;
180 continue;
181 }
182
183 // Select a method with a higher rate
184 if (compare_methods(method, max_method)) {
185 max_task = task;
186 max_method = method;
187 }
188 }
189 task = next_task;
190 }
191
192 if (max_task->comp_level() == CompLevel_full_profile && is_method_profiled(max_method)) {
193 max_task->set_comp_level(CompLevel_limited_profile);
194 if (PrintTieredEvents) {
195 print_event(UPDATE_IN_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
196 }
197 }
198
199 return max_task;
200 }
201
202 double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
203 double queue_size = CompileBroker::queue_size(level);
204 int comp_count = compiler_count(level);
205 double k = queue_size / (feedback_k * comp_count) + 1;
206 return k;
207 }
208
209 // Call and loop predicates determine whether a transition to a higher
210 // compilation level should be performed (pointers to predicate functions
211 // are passed to common()).
212 // Tier?LoadFeedback is basically a coefficient that determines of
213 // how many methods per compiler thread can be in the queue before
214 // the threshold values double.
215 bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level) {
216 switch(cur_level) {
217 case CompLevel_none:
218 case CompLevel_limited_profile: {
219 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
220 return loop_predicate_helper<CompLevel_none>(i, b, k);
221 }
222 case CompLevel_full_profile: {
223 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
224 return loop_predicate_helper<CompLevel_full_profile>(i, b, k);
225 }
226 default:
227 return true;
228 }
229 }
230
231 bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level) {
232 switch(cur_level) {
233 case CompLevel_none:
234 case CompLevel_limited_profile: {
235 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
236 return call_predicate_helper<CompLevel_none>(i, b, k);
237 }
238 case CompLevel_full_profile: {
239 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
240 return call_predicate_helper<CompLevel_full_profile>(i, b, k);
241 }
242 default:
243 return true;
244 }
245 }
246
247 // If a method is old enough and is still in the interpreter we would want to
248 // start profiling without waiting for the compiled method to arrive.
249 // We also take the load on compilers into the account.
250 bool AdvancedThresholdPolicy::should_create_mdo(methodOop method, CompLevel cur_level) {
251 if (cur_level == CompLevel_none &&
252 CompileBroker::queue_size(CompLevel_full_optimization) <=
253 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
254 int i = method->invocation_count();
255 int b = method->backedge_count();
256 double k = Tier0ProfilingStartPercentage / 100.0;
257 return call_predicate_helper<CompLevel_none>(i, b, k) || loop_predicate_helper<CompLevel_none>(i, b, k);
258 }
259 return false;
260 }
261
262 // Inlining control: if we're compiling a profiled method with C1 and the callee
263 // is known to have OSRed in a C2 version, don't inline it.
264 bool AdvancedThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) {
265 CompLevel comp_level = (CompLevel)env->comp_level();
266 if (comp_level == CompLevel_full_profile ||
267 comp_level == CompLevel_limited_profile) {
268 return callee->highest_osr_comp_level() == CompLevel_full_optimization;
269 }
270 return false;
271 }
272
273 // Create MDO if necessary.
274 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, TRAPS) {
275 if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return;
276 if (mh->method_data() == NULL) {
277 methodOopDesc::build_interpreter_method_data(mh, THREAD);
278 if (HAS_PENDING_EXCEPTION) {
279 CLEAR_PENDING_EXCEPTION;
280 }
281 }
282 }
283
284
285 /*
286 * Method states:
287 * 0 - interpreter (CompLevel_none)
288 * 1 - pure C1 (CompLevel_simple)
289 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
290 * 3 - C1 with full profiling (CompLevel_full_profile)
291 * 4 - C2 (CompLevel_full_optimization)
292 *
293 * Common state transition patterns:
294 * a. 0 -> 3 -> 4.
295 * The most common path. But note that even in this straightforward case
296 * profiling can start at level 0 and finish at level 3.
297 *
298 * b. 0 -> 2 -> 3 -> 4.
299 * This case occures when the load on C2 is deemed too high. So, instead of transitioning
300 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to
301 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
302 *
303 * c. 0 -> (3->2) -> 4.
304 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
305 * to enable the profiling to fully occur at level 0. In this case we change the compilation level
306 * of the method to 2, because it'll allow it to run much faster without full profiling while c2
307 * is compiling.
308 *
309 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
310 * After a method was once compiled with C1 it can be identified as trivial and be compiled to
311 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
312 *
313 * e. 0 -> 4.
314 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
315 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
316 * the compiled version already exists).
317 *
318 * Note that since state 0 can be reached from any other state via deoptimization different loops
319 * are possible.
320 *
321 */
322
323 // Common transition function. Given a predicate determines if a method should transition to another level.
324 CompLevel AdvancedThresholdPolicy::common(Predicate p, methodOop method, CompLevel cur_level) {
325 if (is_trivial(method)) return CompLevel_simple;
326
327 CompLevel next_level = cur_level;
328 int i = method->invocation_count();
329 int b = method->backedge_count();
330
331 switch(cur_level) {
332 case CompLevel_none:
333 // If we were at full profile level, would we switch to full opt?
334 if (common(p, method, CompLevel_full_profile) == CompLevel_full_optimization) {
335 next_level = CompLevel_full_optimization;
336 } else if ((this->*p)(i, b, cur_level)) {
337 // C1-generated fully profiled code is about 30% slower than the limited profile
338 // code that has only invocation and backedge counters. The observation is that
339 // if C2 queue is large enough we can spend too much time in the fully profiled code
340 // while waiting for C2 to pick the method from the queue. To alleviate this problem
341 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
342 // we choose to compile a limited profiled version and then recompile with full profiling
343 // when the load on C2 goes down.
344 if (CompileBroker::queue_size(CompLevel_full_optimization) >
345 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
346 next_level = CompLevel_limited_profile;
347 } else {
348 next_level = CompLevel_full_profile;
349 }
350 }
351 break;
352 case CompLevel_limited_profile:
353 if (is_method_profiled(method)) {
354 // Special case: we got here because this method was fully profiled in the interpreter.
355 next_level = CompLevel_full_optimization;
356 } else {
357 methodDataOop mdo = method->method_data();
358 if (mdo != NULL) {
359 if (mdo->would_profile()) {
360 if (CompileBroker::queue_size(CompLevel_full_optimization) <=
361 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
362 (this->*p)(i, b, cur_level)) {
363 next_level = CompLevel_full_profile;
364 }
365 } else {
366 next_level = CompLevel_full_optimization;
367 }
368 }
369 }
370 break;
371 case CompLevel_full_profile:
372 {
373 methodDataOop mdo = method->method_data();
374 if (mdo != NULL) {
375 if (mdo->would_profile()) {
376 int mdo_i = mdo->invocation_count_delta();
377 int mdo_b = mdo->backedge_count_delta();
378 if ((this->*p)(mdo_i, mdo_b, cur_level)) {
379 next_level = CompLevel_full_optimization;
380 }
381 } else {
382 next_level = CompLevel_full_optimization;
383 }
384 }
385 }
386 break;
387 }
388 return next_level;
389 }
390
391 // Determine if a method should be compiled with a normal entry point at a different level.
392 CompLevel AdvancedThresholdPolicy::call_event(methodOop method, CompLevel cur_level) {
393 CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(),
394 common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level));
395 CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);
396
397 // If OSR method level is greater than the regular method level, the levels should be
398 // equalized by raising the regular method level in order to avoid OSRs during each
399 // invocation of the method.
400 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
401 methodDataOop mdo = method->method_data();
402 guarantee(mdo != NULL, "MDO should not be NULL");
403 if (mdo->invocation_count() >= 1) {
404 next_level = CompLevel_full_optimization;
405 }
406 } else {
407 next_level = MAX2(osr_level, next_level);
408 }
409
410 return next_level;
411 }
412
413 // Determine if we should do an OSR compilation of a given method.
414 CompLevel AdvancedThresholdPolicy::loop_event(methodOop method, CompLevel cur_level) {
415 CompLevel next_level = common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level);
416 if (cur_level == CompLevel_none) {
417 // If there is a live OSR method that means that we deopted to the interpreter
418 // for the transition.
419 CompLevel osr_level = MIN2((CompLevel)method->highest_osr_comp_level(), next_level);
420 if (osr_level > CompLevel_none) {
421 return osr_level;
422 }
423 }
424 return next_level;
425 }
426
427 // Update the rate and submit compile
428 void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, TRAPS) {
429 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
430 update_rate(os::javaTimeMillis(), mh());
431 CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", THREAD);
432 }
433
434 // Handle the invocation event.
435 void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh,
436 CompLevel level, nmethod* nm, TRAPS) {
437 if (should_create_mdo(mh(), level)) {
438 create_mdo(mh, THREAD);
439 }
440 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, InvocationEntryBci)) {
441 CompLevel next_level = call_event(mh(), level);
442 if (next_level != level) {
443 compile(mh, InvocationEntryBci, next_level, THREAD);
444 }
445 }
446 }
447
448 // Handle the back branch event. Notice that we can compile the method
449 // with a regular entry from here.
450 void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh,
451 int bci, CompLevel level, nmethod* nm, TRAPS) {
452 if (should_create_mdo(mh(), level)) {
453 create_mdo(mh, THREAD);
454 }
455 // Check if MDO should be created for the inlined method
456 if (should_create_mdo(imh(), level)) {
457 create_mdo(imh, THREAD);
458 }
459
460 if (is_compilation_enabled()) {
461 CompLevel next_osr_level = loop_event(imh(), level);
462 CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level();
463 if (next_osr_level == CompLevel_limited_profile) {
464 next_osr_level = CompLevel_full_profile; // OSRs are supposed to be for very hot methods.
465 }
466
467 // At the very least compile the OSR version
468 if (!CompileBroker::compilation_is_in_queue(imh, bci)) {
469 // Check if there's a method like that already
470 nmethod* osr_nm = NULL;
471 if (max_osr_level >= next_osr_level) {
472 // There is an osr method already with the same
473 // or greater level, check if it has the bci we need
474 osr_nm = imh->lookup_osr_nmethod_for(bci, next_osr_level, false);
475 }
476 if (osr_nm == NULL) {
477 compile(imh, bci, next_osr_level, THREAD);
478 }
479 }
480
481 // Use loop event as an opportunity to also check if there's been
482 // enough calls.
483 CompLevel cur_level, next_level;
484 if (mh() != imh()) { // If there is an enclosing method
485 guarantee(nm != NULL, "Should have nmethod here");
486 cur_level = comp_level(mh());
487 next_level = call_event(mh(), cur_level);
488
489 if (max_osr_level == CompLevel_full_optimization) {
490 // The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts
491 bool make_not_entrant = false;
492 if (nm->is_osr_method()) {
493 // This is an osr method, just make it not entrant and recompile later if needed
494 make_not_entrant = true;
495 } else {
496 if (next_level != CompLevel_full_optimization) {
497 // next_level is not full opt, so we need to recompile the
498 // enclosing method without the inlinee
499 cur_level = CompLevel_none;
500 make_not_entrant = true;
501 }
502 }
503 if (make_not_entrant) {
504 if (PrintTieredEvents) {
505 int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci;
506 print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level);
507 }
508 nm->make_not_entrant();
509 }
510 }
511 if (!CompileBroker::compilation_is_in_queue(mh, InvocationEntryBci)) {
512 // Fix up next_level if necessary to avoid deopts
513 if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) {
514 next_level = CompLevel_full_profile;
515 }
516 if (cur_level != next_level) {
517 compile(mh, InvocationEntryBci, next_level, THREAD);
518 }
519 }
520 } else {
521 cur_level = comp_level(imh());
522 next_level = call_event(imh(), cur_level);
523 if (!CompileBroker::compilation_is_in_queue(imh, bci) && next_level != cur_level) {
524 compile(imh, InvocationEntryBci, next_level, THREAD);
525 }
526 }
527 }
528 }
529
530 #endif // TIERED