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(KILL, 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, 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 // Create MDO if necessary.
263 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, TRAPS) {
264 if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return;
265 if (mh->method_data() == NULL) {
266 methodOopDesc::build_interpreter_method_data(mh, THREAD);
267 if (HAS_PENDING_EXCEPTION) {
268 CLEAR_PENDING_EXCEPTION;
269 }
270 }
271 }
272
273
274 /*
275 * Method states:
276 * 0 - interpreter (CompLevel_none)
277 * 1 - pure C1 (CompLevel_simple)
278 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
279 * 3 - C1 with full profiling (CompLevel_full_profile)
280 * 4 - C2 (CompLevel_full_optimization)
281 *
282 * Common state transition patterns:
283 * a. 0 -> 3 -> 4.
284 * The most common path. But note that even in this straightforward case
285 * profiling can start at level 0 and finish at level 3.
286 *
287 * b. 0 -> 2 -> 3 -> 4.
288 * This case occures when the load on C2 is deemed too high. So, instead of transitioning
289 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to
290 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
291 *
292 * c. 0 -> (3->2) -> 4.
293 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
294 * to enable the profiling to fully occur at level 0. In this case we change the compilation level
295 * of the method to 2, because it'll allow it to run much faster without full profiling while c2
296 * is compiling.
297 *
298 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
299 * After a method was once compiled with C1 it can be identified as trivial and be compiled to
300 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
301 *
302 * e. 0 -> 4.
303 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
304 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
305 * the compiled version already exists).
306 *
307 * Note that since state 0 can be reached from any other state via deoptimization different loops
308 * are possible.
309 *
310 */
311
312 // Common transition function. Given a predicate determines if a method should transition to another level.
313 CompLevel AdvancedThresholdPolicy::common(Predicate p, methodOop method, CompLevel cur_level) {
314 if (is_trivial(method)) return CompLevel_simple;
315
316 CompLevel next_level = cur_level;
317 int i = method->invocation_count();
318 int b = method->backedge_count();
319
320 switch(cur_level) {
321 case CompLevel_none:
322 // If we were at full profile level, would we switch to full opt?
323 if (common(p, method, CompLevel_full_profile) == CompLevel_full_optimization) {
324 next_level = CompLevel_full_optimization;
325 } else if ((this->*p)(i, b, cur_level)) {
326 // C1-generated fully profiled code is about 30% slower than the limited profile
327 // code that has only invocation and backedge counters. The observation is that
328 // if C2 queue is large enough we can spend too much time in the fully profiled code
329 // while waiting for C2 to pick the method from the queue. To alleviate this problem
330 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
331 // we choose to compile a limited profiled version and then recompile with full profiling
332 // when the load on C2 goes down.
333 if (CompileBroker::queue_size(CompLevel_full_optimization) >
334 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
335 next_level = CompLevel_limited_profile;
336 } else {
337 next_level = CompLevel_full_profile;
338 }
339 }
340 break;
341 case CompLevel_limited_profile:
342 if (is_method_profiled(method)) {
343 // Special case: we got here because this method was fully profiled in the interpreter.
344 next_level = CompLevel_full_optimization;
345 } else {
346 methodDataOop mdo = method->method_data();
347 if (mdo != NULL) {
348 if (mdo->would_profile()) {
349 if (CompileBroker::queue_size(CompLevel_full_optimization) <=
350 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
351 (this->*p)(i, b, cur_level)) {
352 next_level = CompLevel_full_profile;
353 }
354 } else {
355 next_level = CompLevel_full_optimization;
356 }
357 }
358 }
359 break;
360 case CompLevel_full_profile:
361 {
362 methodDataOop mdo = method->method_data();
363 if (mdo != NULL) {
364 if (mdo->would_profile()) {
365 int mdo_i = mdo->invocation_count_delta();
366 int mdo_b = mdo->backedge_count_delta();
367 if ((this->*p)(mdo_i, mdo_b, cur_level)) {
368 next_level = CompLevel_full_optimization;
369 }
370 } else {
371 next_level = CompLevel_full_optimization;
372 }
373 }
374 }
375 break;
376 }
377 return next_level;
378 }
379
380 // Determine if a method should be compiled with a normal entry point at a different level.
381 CompLevel AdvancedThresholdPolicy::call_event(methodOop method, CompLevel cur_level) {
382 CompLevel osr_level = (CompLevel) method->highest_osr_comp_level();
383 CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);
384
385 // If OSR method level is greater than the regular method level, the levels should be
386 // equalized by raising the regular method level in order to avoid OSRs during each
387 // invocation of the method.
388 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
389 methodDataOop mdo = method->method_data();
390 guarantee(mdo != NULL, "MDO should not be NULL");
391 if (mdo->invocation_count() >= 1) {
392 next_level = CompLevel_full_optimization;
393 }
394 } else {
395 next_level = MAX2(osr_level, next_level);
396 }
397
398 return next_level;
399 }
400
401 // Determine if we should do an OSR compilation of a given method.
402 CompLevel AdvancedThresholdPolicy::loop_event(methodOop method, CompLevel cur_level) {
403 if (cur_level == CompLevel_none) {
404 // If there is a live OSR method that means that we deopted to the interpreter
405 // for the transition.
406 CompLevel osr_level = (CompLevel)method->highest_osr_comp_level();
407 if (osr_level > CompLevel_none) {
408 return osr_level;
409 }
410 }
411 return common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level);
412 }
413
414 // Update the rate and submit compile
415 void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, TRAPS) {
416 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
417 update_rate(os::javaTimeMillis(), mh());
418 CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", THREAD);
419 }
420
421
422 // Handle the invocation event.
423 void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh,
424 CompLevel level, TRAPS) {
425 if (should_create_mdo(mh(), level)) {
426 create_mdo(mh, THREAD);
427 }
428 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, InvocationEntryBci)) {
429 CompLevel next_level = call_event(mh(), level);
430 if (next_level != level) {
431 compile(mh, InvocationEntryBci, next_level, THREAD);
432 }
433 }
434 }
435
436 // Handle the back branch event. Notice that we can compile the method
437 // with a regular entry from here.
438 void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh,
439 int bci, CompLevel level, TRAPS) {
440 if (should_create_mdo(mh(), level)) {
441 create_mdo(mh, THREAD);
442 }
443
444 // If the method is already compiling, quickly bail out.
445 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, bci)) {
446 // Use loop event as an opportinity to also check there's been
447 // enough calls.
448 CompLevel cur_level = comp_level(mh());
449 CompLevel next_level = call_event(mh(), cur_level);
450 CompLevel next_osr_level = loop_event(mh(), level);
451 if (next_osr_level == CompLevel_limited_profile) {
452 next_osr_level = CompLevel_full_profile; // OSRs are supposed to be for very hot methods.
453 }
454 next_level = MAX2(next_level,
455 next_osr_level < CompLevel_full_optimization ? next_osr_level : cur_level);
456 bool is_compiling = false;
457 if (next_level != cur_level) {
458 compile(mh, InvocationEntryBci, next_level, THREAD);
459 is_compiling = true;
460 }
461
462 // Do the OSR version
463 if (!is_compiling && next_osr_level != level) {
464 compile(mh, bci, next_osr_level, THREAD);
465 }
466 }
467 }
468
469 #endif // TIERED