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