1 /*
2 * Copyright (c) 2010, 2011 Oracle and/or its affiliates. All rights reserved.
3 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
4 */
5
6 #include "precompiled.hpp"
7 #include "runtime/advancedThresholdPolicy.hpp"
8 #include "runtime/simpleThresholdPolicy.inline.hpp"
9
10 #ifdef TIERED
11 // Print an event.
12 void AdvancedThresholdPolicy::print_specific(EventType type, methodHandle mh, methodHandle imh,
13 int bci, CompLevel level) {
14 tty->print(" rate: ");
15 if (mh->prev_time() == 0) tty->print("n/a");
16 else tty->print("%f", mh->rate());
17
18 tty->print(" k: %.2lf,%.2lf", threshold_scale(CompLevel_full_profile, Tier3LoadFeedback),
19 threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));
20
21 }
22
23 void AdvancedThresholdPolicy::initialize() {
24 // Turn on ergonomic compiler count selection
25 if (FLAG_IS_DEFAULT(CICompilerCountPerCPU) && FLAG_IS_DEFAULT(CICompilerCount)) {
26 FLAG_SET_DEFAULT(CICompilerCountPerCPU, true);
27 }
28 int count = CICompilerCount;
29 if (CICompilerCountPerCPU) {
30 // Simple log n seems to grow too slowly for tiered, try something faster: log n * log log n
31 int log_cpu = log2_intptr(os::active_processor_count());
32 int loglog_cpu = log2_intptr(MAX2(log_cpu, 1));
33 count = MAX2(log_cpu * loglog_cpu, 1) * 3 / 2;
34 }
35
36 set_c1_count(MAX2(count / 3, 1));
37 set_c2_count(MAX2(count - count / 3, 1));
38
39 // Some inlining tuning
40 #ifdef X86
41 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
42 FLAG_SET_DEFAULT(InlineSmallCode, 2000);
43 }
44 #endif
45
46 #ifdef SPARC
47 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
48 FLAG_SET_DEFAULT(InlineSmallCode, 2500);
49 }
50 #endif
51
52
53 set_start_time(os::javaTimeMillis());
54 }
55
56 // update_rate() is called from select_task() while holding a compile queue lock.
57 void AdvancedThresholdPolicy::update_rate(jlong t, methodOop m) {
58 if (is_old(m)) {
59 // We don't remove old methods from the queue,
60 // so we can just zero the rate.
61 m->set_rate(0);
62 return;
63 }
64
65 // We don't update the rate if we've just came out of a safepoint.
66 // delta_s is the time since last safepoint in milliseconds.
67 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
68 jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement
69 // How many events were there since the last time?
70 int event_count = m->invocation_count() + m->backedge_count();
71 int delta_e = event_count - m->prev_event_count();
72
73 // We should be running for at least 1ms.
74 if (delta_s >= TieredRateUpdateMinTime) {
75 // And we must've taken the previous point at least 1ms before.
76 if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) {
77 m->set_prev_time(t);
78 m->set_prev_event_count(event_count);
79 m->set_rate((float)delta_e / (float)delta_t); // Rate is events per millisecond
80 } else
81 if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) {
82 // If nothing happened for 25ms, zero the rate. Don't modify prev values.
83 m->set_rate(0);
84 }
85 }
86 }
87
88 // Check if this method has been stale from a given number of milliseconds.
89 // See select_task().
90 bool AdvancedThresholdPolicy::is_stale(jlong t, jlong timeout, methodOop m) {
91 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
92 jlong delta_t = t - m->prev_time();
93 if (delta_t > timeout && delta_s > timeout) {
94 int event_count = m->invocation_count() + m->backedge_count();
95 int delta_e = event_count - m->prev_event_count();
96 // Return true if there were no events.
97 return delta_e == 0;
98 }
99 return false;
100 }
101
102 // We don't remove old methods from the compile queue even if they have
103 // very low activity. See select_task().
104 bool AdvancedThresholdPolicy::is_old(methodOop method) {
105 return method->invocation_count() > 50000 || method->backedge_count() > 500000;
106 }
107
108 double AdvancedThresholdPolicy::weight(methodOop method) {
109 return (method->rate() + 1) * ((method->invocation_count() + 1) * (method->backedge_count() + 1));
110 }
111
112 // Apply heuristics and return true if x should be compiled before y
113 bool AdvancedThresholdPolicy::compare_methods(methodOop x, methodOop y) {
114 if (x->highest_comp_level() > y->highest_comp_level()) {
115 // recompilation after deopt
116 return true;
117 } else
118 if (x->highest_comp_level() == y->highest_comp_level()) {
119 if (weight(x) > weight(y)) {
120 return true;
121 }
122 }
123 return false;
124 }
125
126 // Is method profiled enough?
127 bool AdvancedThresholdPolicy::is_method_profiled(methodOop method) {
128 methodDataOop mdo = method->method_data();
129 if (mdo != NULL) {
130 int i = mdo->invocation_count_delta();
131 int b = mdo->backedge_count_delta();
132 return call_predicate_helper<CompLevel_full_profile>(i, b, 1);
133 }
134 return false;
135 }
136
137 // Called with the queue locked and with at least one element
138 CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {
139 CompileTask *max_task = NULL;
140 methodOop max_method;
141 jlong t = os::javaTimeMillis();
142 // Iterate through the queue and find a method with a maximum rate.
143 for (CompileTask* task = compile_queue->first(); task != NULL;) {
144 CompileTask* next_task = task->next();
145 methodOop method = (methodOop)JNIHandles::resolve(task->method_handle());
146 methodDataOop mdo = method->method_data();
147 update_rate(t, method);
148 if (max_task == NULL) {
149 max_task = task;
150 max_method = method;
151 } else {
152 // If a method has been stale for some time, remove it from the queue.
153 if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) {
154 if (PrintTieredEvents) {
155 print_event(KILL, method, method, task->osr_bci(), (CompLevel)task->comp_level());
156 }
157 CompileTaskWrapper ctw(task); // Frees the task
158 compile_queue->remove(task);
159 method->clear_queued_for_compilation();
160 task = next_task;
161 continue;
162 }
163
164 // Select a method with a higher rate
165 if (compare_methods(method, max_method)) {
166 max_task = task;
167 max_method = method;
168 }
169 }
170 task = next_task;
171 }
172
173 if (max_task->comp_level() == CompLevel_full_profile && is_method_profiled(max_method)) {
174 max_task->set_comp_level(CompLevel_limited_profile);
175 if (PrintTieredEvents) {
176 print_event(UPDATE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
177 }
178 }
179
180 return max_task;
181 }
182
183 double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
184 double queue_size = CompileBroker::queue_size(level);
185 int comp_count = compiler_count(level);
186 double k = queue_size / (feedback_k * comp_count) + 1;
187 return k;
188 }
189
190 // Call and loop predicates determine whether a transition to a higher
191 // compilation level should be performed (pointers to predicate functions
192 // are passed to common()).
193 // Tier?LoadFeedback is basically a coefficient that determines of
194 // how many methods per compiler thread can be in the queue before
195 // the threshold values double.
196 bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level) {
197 switch(cur_level) {
198 case CompLevel_none:
199 case CompLevel_limited_profile: {
200 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
201 return loop_predicate_helper<CompLevel_none>(i, b, k);
202 }
203 case CompLevel_full_profile: {
204 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
205 return loop_predicate_helper<CompLevel_full_profile>(i, b, k);
206 }
207 default:
208 return true;
209 }
210 }
211
212 bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level) {
213 switch(cur_level) {
214 case CompLevel_none:
215 case CompLevel_limited_profile: {
216 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
217 return call_predicate_helper<CompLevel_none>(i, b, k);
218 }
219 case CompLevel_full_profile: {
220 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
221 return call_predicate_helper<CompLevel_full_profile>(i, b, k);
222 }
223 default:
224 return true;
225 }
226 }
227
228 // If a method is old enough and is still in the interpreter we would want to
229 // start profiling without waiting for the compiled method to arrive.
230 // We also take the load on compilers into the account.
231 bool AdvancedThresholdPolicy::should_create_mdo(methodOop method, CompLevel cur_level) {
232 if (cur_level == CompLevel_none &&
233 CompileBroker::queue_size(CompLevel_full_optimization) <=
234 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
235 int i = method->invocation_count();
236 int b = method->backedge_count();
237 double k = Tier0ProfilingStartPercentage / 100.0;
238 return call_predicate_helper<CompLevel_none>(i, b, k) || loop_predicate_helper<CompLevel_none>(i, b, k);
239 }
240 return false;
241 }
242
243 // Create MDO if necessary.
244 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, TRAPS) {
245 if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return;
246 if (mh->method_data() == NULL) {
247 methodOopDesc::build_interpreter_method_data(mh, THREAD);
248 if (HAS_PENDING_EXCEPTION) {
249 CLEAR_PENDING_EXCEPTION;
250 }
251 }
252 }
253
254
255 /*
256 * Method states:
257 * 0 - interpreter (CompLevel_none)
258 * 1 - pure C1 (CompLevel_simple)
259 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
260 * 3 - C1 with full profiling (CompLevel_full_profile)
261 * 4 - C2 (CompLevel_full_optimization)
262 *
263 * Common state transition patterns:
264 * a. 0 -> 3 -> 4.
265 * The most common path. But note that even in this straightforward case
266 * profiling can start at level 0 and finish at level 3.
267 *
268 * b. 0 -> 2 -> 3 -> 4.
269 * This case occures when the load on C2 is deemed too high. So, instead of transitioning
270 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to
271 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
272 *
273 * c. 0 -> (3->2) -> 4.
274 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
275 * to enable the profiling to fully occur at level 0. In this case we change the compilation level
276 * of the method to 2, because it'll allow it to run much faster without full profiling while c2
277 * is compiling.
278 *
279 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
280 * After a method was once compiled with C1 it can be identified as trivial and be compiled to
281 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
282 *
283 * e. 0 -> 4.
284 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
285 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
286 * the compiled version already exists).
287 *
288 * Note that since state 0 can be reached from any other state via deoptimization different loops
289 * are possible.
290 *
291 */
292
293 // Common transition function. Given a predicate determines if a method should transition to another level.
294 CompLevel AdvancedThresholdPolicy::common(Predicate p, methodOop method, CompLevel cur_level) {
295 if (is_trivial(method)) return CompLevel_simple;
296
297 CompLevel next_level = cur_level;
298 int i = method->invocation_count();
299 int b = method->backedge_count();
300
301 switch(cur_level) {
302 case CompLevel_none:
303 // If we were at full profile level, would we switch to full opt?
304 if (common(p, method, CompLevel_full_profile) == CompLevel_full_optimization) {
305 next_level = CompLevel_full_optimization;
306 } else if ((this->*p)(i, b, cur_level)) {
307 // C1-generated fully profiled code is about 30% slower than the limited profile
308 // code that has only invocation and backedge counters. The observation is that
309 // if C2 queue is large enough we can spend too much time in the fully profiled code
310 // while waiting for C2 to pick the method from the queue. To alleviate this problem
311 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
312 // we choose to compile a limited profiled version and then recompile with full profiling
313 // when the load on C2 goes down.
314 if (CompileBroker::queue_size(CompLevel_full_optimization) >
315 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
316 next_level = CompLevel_limited_profile;
317 } else {
318 next_level = CompLevel_full_profile;
319 }
320 }
321 break;
322 case CompLevel_limited_profile:
323 if (is_method_profiled(method)) {
324 // Special case: we got here because this method was fully profiled in the interpreter.
325 next_level = CompLevel_full_optimization;
326 } else {
327 methodDataOop mdo = method->method_data();
328 if (mdo != NULL) {
329 if (mdo->would_profile()) {
330 if (CompileBroker::queue_size(CompLevel_full_optimization) <=
331 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
332 (this->*p)(i, b, cur_level)) {
333 next_level = CompLevel_full_profile;
334 }
335 } else {
336 next_level = CompLevel_full_optimization;
337 }
338 }
339 }
340 break;
341 case CompLevel_full_profile:
342 {
343 methodDataOop mdo = method->method_data();
344 if (mdo != NULL) {
345 if (mdo->would_profile()) {
346 int mdo_i = mdo->invocation_count_delta();
347 int mdo_b = mdo->backedge_count_delta();
348 if ((this->*p)(mdo_i, mdo_b, cur_level)) {
349 next_level = CompLevel_full_optimization;
350 }
351 } else {
352 next_level = CompLevel_full_optimization;
353 }
354 }
355 }
356 break;
357 }
358 return next_level;
359 }
360
361 // Determine if a method should be compiled with a normal entry point at a different level.
362 CompLevel AdvancedThresholdPolicy::call_event(methodOop method, CompLevel cur_level) {
363 CompLevel osr_level = (CompLevel) method->highest_osr_comp_level();
364 CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);
365
366 // If OSR method level is greater than the regular method level, the levels should be
367 // equalized by raising the regular method level in order to avoid OSRs during each
368 // invocation of the method.
369 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
370 methodDataOop mdo = method->method_data();
371 guarantee(mdo != NULL, "MDO should not be NULL");
372 if (mdo->invocation_count() >= 1) {
373 next_level = CompLevel_full_optimization;
374 }
375 } else {
376 next_level = MAX2(osr_level, next_level);
377 }
378
379 return next_level;
380 }
381
382 // Determine if we should do an OSR compilation of a given method.
383 CompLevel AdvancedThresholdPolicy::loop_event(methodOop method, CompLevel cur_level) {
384 if (cur_level == CompLevel_none) {
385 // If there is a live OSR method that means that we deopted to the interpreter
386 // for the transition.
387 CompLevel osr_level = (CompLevel)method->highest_osr_comp_level();
388 if (osr_level > CompLevel_none) {
389 return osr_level;
390 }
391 }
392 return common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level);
393 }
394
395 // Update the rate and submit compile
396 void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, TRAPS) {
397 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
398 update_rate(os::javaTimeMillis(), mh());
399 CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", THREAD);
400 }
401
402
403 // Handle the invocation event.
404 void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh,
405 CompLevel level, TRAPS) {
406 if (should_create_mdo(mh(), level)) {
407 create_mdo(mh, THREAD);
408 }
409 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, InvocationEntryBci)) {
410 CompLevel next_level = call_event(mh(), level);
411 if (next_level != level) {
412 compile(mh, InvocationEntryBci, next_level, THREAD);
413 }
414 }
415 }
416
417 // Handle the back branch event. Notice that we can compile the method
418 // with a regular entry from here.
419 void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh,
420 int bci, CompLevel level, TRAPS) {
421 if (should_create_mdo(mh(), level)) {
422 create_mdo(mh, THREAD);
423 }
424
425 // If the method is already compiling, quickly bail out.
426 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, bci)) {
427 // Use loop event as an opportinity to also check there's been
428 // enough calls.
429 CompLevel cur_level = comp_level(mh());
430 CompLevel next_level = call_event(mh(), cur_level);
431 CompLevel next_osr_level = loop_event(mh(), level);
432 if (next_osr_level == CompLevel_limited_profile) {
433 next_osr_level = CompLevel_full_profile; // OSRs are supposed to be for very hot methods.
434 }
435 next_level = MAX2(next_level,
436 next_osr_level < CompLevel_full_optimization ? next_osr_level : cur_level);
437 bool is_compiling = false;
438 if (next_level != cur_level) {
439 compile(mh, InvocationEntryBci, next_level, THREAD);
440 is_compiling = true;
441 }
442
443 // Do the OSR version
444 if (!is_compiling && next_osr_level != level) {
445 compile(mh, bci, next_osr_level, THREAD);
446 }
447 }
448 }
449
450 #endif // TIERED