src/share/vm/runtime/advancedThresholdPolicy.cpp - platform/external/jetbrains/jdk8u_hotspot - Git at Google

 /*
  * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */

 #include "precompiled.hpp"
 #include "runtime/advancedThresholdPolicy.hpp"
 #include "runtime/simpleThresholdPolicy.inline.hpp"

 #ifdef TIERED
 // Print an event.
 void AdvancedThresholdPolicy::print_specific(EventType type, methodHandle mh, methodHandle imh,
                                              int bci, CompLevel level) {
   tty->print(" rate=");
   if (mh->prev_time() == 0) tty->print("n/a");
   else tty->print("%f", mh->rate());

   tty->print(" k=%.2lf,%.2lf", threshold_scale(CompLevel_full_profile, Tier3LoadFeedback),
                                threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));

 }

 void AdvancedThresholdPolicy::initialize() {
   // Turn on ergonomic compiler count selection
   if (FLAG_IS_DEFAULT(CICompilerCountPerCPU) && FLAG_IS_DEFAULT(CICompilerCount)) {
     FLAG_SET_DEFAULT(CICompilerCountPerCPU, true);
   }
   int count = CICompilerCount;
   if (CICompilerCountPerCPU) {
     // Simple log n seems to grow too slowly for tiered, try something faster: log n * log log n
     int log_cpu = log2_intptr(os::active_processor_count());
     int loglog_cpu = log2_intptr(MAX2(log_cpu, 1));
     count = MAX2(log_cpu * loglog_cpu, 1) * 3 / 2;
   }

   set_c1_count(MAX2(count / 3, 1));
   set_c2_count(MAX2(count - c1_count(), 1));
   FLAG_SET_ERGO(intx, CICompilerCount, c1_count() + c2_count());

   // Some inlining tuning
 #ifdef X86
   if (FLAG_IS_DEFAULT(InlineSmallCode)) {
     FLAG_SET_DEFAULT(InlineSmallCode, 2000);
   }
 #endif

 #ifdef SPARC
   if (FLAG_IS_DEFAULT(InlineSmallCode)) {
     FLAG_SET_DEFAULT(InlineSmallCode, 2500);
   }
 #endif

   set_increase_threshold_at_ratio();
   set_start_time(os::javaTimeMillis());
 }

 // update_rate() is called from select_task() while holding a compile queue lock.
 void AdvancedThresholdPolicy::update_rate(jlong t, Method* m) {
   // Skip update if counters are absent.
   // Can't allocate them since we are holding compile queue lock.
   if (m->method_counters() == NULL)  return;

   if (is_old(m)) {
     // We don't remove old methods from the queue,
     // so we can just zero the rate.
     m->set_rate(0);
     return;
   }

   // We don't update the rate if we've just came out of a safepoint.
   // delta_s is the time since last safepoint in milliseconds.
   jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
   jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement
   // How many events were there since the last time?
   int event_count = m->invocation_count() + m->backedge_count();
   int delta_e = event_count - m->prev_event_count();

   // We should be running for at least 1ms.
   if (delta_s >= TieredRateUpdateMinTime) {
     // And we must've taken the previous point at least 1ms before.
     if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) {
       m->set_prev_time(t);
       m->set_prev_event_count(event_count);
       m->set_rate((float)delta_e / (float)delta_t); // Rate is events per millisecond
     } else {
       if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) {
         // If nothing happened for 25ms, zero the rate. Don't modify prev values.
         m->set_rate(0);
       }
     }
   }
 }

 // Check if this method has been stale from a given number of milliseconds.
 // See select_task().
 bool AdvancedThresholdPolicy::is_stale(jlong t, jlong timeout, Method* m) {
   jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
   jlong delta_t = t - m->prev_time();
   if (delta_t > timeout && delta_s > timeout) {
     int event_count = m->invocation_count() + m->backedge_count();
     int delta_e = event_count - m->prev_event_count();
     // Return true if there were no events.
     return delta_e == 0;
   }
   return false;
 }

 // We don't remove old methods from the compile queue even if they have
 // very low activity. See select_task().
 bool AdvancedThresholdPolicy::is_old(Method* method) {
   return method->invocation_count() > 50000 || method->backedge_count() > 500000;
 }

 double AdvancedThresholdPolicy::weight(Method* method) {
   return (method->rate() + 1) * ((method->invocation_count() + 1) *  (method->backedge_count() + 1));
 }

 // Apply heuristics and return true if x should be compiled before y
 bool AdvancedThresholdPolicy::compare_methods(Method* x, Method* y) {
   if (x->highest_comp_level() > y->highest_comp_level()) {
     // recompilation after deopt
     return true;
   } else
     if (x->highest_comp_level() == y->highest_comp_level()) {
       if (weight(x) > weight(y)) {
         return true;
       }
     }
   return false;
 }

 // Is method profiled enough?
 bool AdvancedThresholdPolicy::is_method_profiled(Method* method) {
   MethodData* mdo = method->method_data();
   if (mdo != NULL) {
     int i = mdo->invocation_count_delta();
     int b = mdo->backedge_count_delta();
     return call_predicate_helper<CompLevel_full_profile>(i, b, 1);
   }
   return false;
 }

 // Called with the queue locked and with at least one element
 CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {
   CompileTask *max_task = NULL;
   Method* max_method = NULL;
   jlong t = os::javaTimeMillis();
   // Iterate through the queue and find a method with a maximum rate.
   for (CompileTask* task = compile_queue->first(); task != NULL;) {
     CompileTask* next_task = task->next();
     Method* method = task->method();
     update_rate(t, method);
     if (max_task == NULL) {
       max_task = task;
       max_method = method;
     } else {
       // If a method has been stale for some time, remove it from the queue.
       if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) {
         if (PrintTieredEvents) {
           print_event(REMOVE_FROM_QUEUE, method, method, task->osr_bci(), (CompLevel)task->comp_level());
         }
         compile_queue->remove_and_mark_stale(task);
         method->clear_queued_for_compilation();
         task = next_task;
         continue;
       }

       // Select a method with a higher rate
       if (compare_methods(method, max_method)) {
         max_task = task;
         max_method = method;
       }
     }
     task = next_task;
   }

   if (max_task->comp_level() == CompLevel_full_profile && TieredStopAtLevel > CompLevel_full_profile
       && is_method_profiled(max_method)) {
     max_task->set_comp_level(CompLevel_limited_profile);
     if (PrintTieredEvents) {
       print_event(UPDATE_IN_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
     }
   }

   return max_task;
 }

 double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
   double queue_size = CompileBroker::queue_size(level);
   int comp_count = compiler_count(level);
   double k = queue_size / (feedback_k * comp_count) + 1;

   // Increase C1 compile threshold when the code cache is filled more
   // than specified by IncreaseFirstTierCompileThresholdAt percentage.
   // The main intention is to keep enough free space for C2 compiled code
   // to achieve peak performance if the code cache is under stress.
   if ((TieredStopAtLevel == CompLevel_full_optimization) && (level != CompLevel_full_optimization))  {
     double current_reverse_free_ratio = CodeCache::reverse_free_ratio();
     if (current_reverse_free_ratio > _increase_threshold_at_ratio) {
       k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio);
     }
   }
   return k;
 }

 // Call and loop predicates determine whether a transition to a higher
 // compilation level should be performed (pointers to predicate functions
 // are passed to common()).
 // Tier?LoadFeedback is basically a coefficient that determines of
 // how many methods per compiler thread can be in the queue before
 // the threshold values double.
 bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level) {
   switch(cur_level) {
   case CompLevel_none:
   case CompLevel_limited_profile: {
     double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
     return loop_predicate_helper<CompLevel_none>(i, b, k);
   }
   case CompLevel_full_profile: {
     double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
     return loop_predicate_helper<CompLevel_full_profile>(i, b, k);
   }
   default:
     return true;
   }
 }

 bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level) {
   switch(cur_level) {
   case CompLevel_none:
   case CompLevel_limited_profile: {
     double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
     return call_predicate_helper<CompLevel_none>(i, b, k);
   }
   case CompLevel_full_profile: {
     double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
     return call_predicate_helper<CompLevel_full_profile>(i, b, k);
   }
   default:
     return true;
   }
 }

 // If a method is old enough and is still in the interpreter we would want to
 // start profiling without waiting for the compiled method to arrive.
 // We also take the load on compilers into the account.
 bool AdvancedThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) {
   if (cur_level == CompLevel_none &&
       CompileBroker::queue_size(CompLevel_full_optimization) <=
       Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
     int i = method->invocation_count();
     int b = method->backedge_count();
     double k = Tier0ProfilingStartPercentage / 100.0;
     return call_predicate_helper<CompLevel_none>(i, b, k) || loop_predicate_helper<CompLevel_none>(i, b, k);
   }
   return false;
 }

 // Inlining control: if we're compiling a profiled method with C1 and the callee
 // is known to have OSRed in a C2 version, don't inline it.
 bool AdvancedThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) {
   CompLevel comp_level = (CompLevel)env->comp_level();
   if (comp_level == CompLevel_full_profile ||
       comp_level == CompLevel_limited_profile) {
     return callee->highest_osr_comp_level() == CompLevel_full_optimization;
   }
   return false;
 }

 // Create MDO if necessary.
 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, JavaThread* THREAD) {
   if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return;
   if (mh->method_data() == NULL) {
     Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR);
   }
 }


 /*
  * Method states:
  *   0 - interpreter (CompLevel_none)
  *   1 - pure C1 (CompLevel_simple)
  *   2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
  *   3 - C1 with full profiling (CompLevel_full_profile)
  *   4 - C2 (CompLevel_full_optimization)
  *
  * Common state transition patterns:
  * a. 0 -> 3 -> 4.
  *    The most common path. But note that even in this straightforward case
  *    profiling can start at level 0 and finish at level 3.
  *
  * b. 0 -> 2 -> 3 -> 4.
  *    This case occures when the load on C2 is deemed too high. So, instead of transitioning
  *    into state 3 directly and over-profiling while a method is in the C2 queue we transition to
  *    level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
  *
  * c. 0 -> (3->2) -> 4.
  *    In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
  *    to enable the profiling to fully occur at level 0. In this case we change the compilation level
  *    of the method to 2 while the request is still in-queue, because it'll allow it to run much faster
  *    without full profiling while c2 is compiling.
  *
  * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
  *    After a method was once compiled with C1 it can be identified as trivial and be compiled to
  *    level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
  *
  * e. 0 -> 4.
  *    This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
  *    or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
  *    the compiled version already exists).
  *
  * Note that since state 0 can be reached from any other state via deoptimization different loops
  * are possible.
  *
  */

 // Common transition function. Given a predicate determines if a method should transition to another level.
 CompLevel AdvancedThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) {
   CompLevel next_level = cur_level;
   int i = method->invocation_count();
   int b = method->backedge_count();

   if (is_trivial(method)) {
     next_level = CompLevel_simple;
   } else {
     switch(cur_level) {
     case CompLevel_none:
       // If we were at full profile level, would we switch to full opt?
       if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) {
         next_level = CompLevel_full_optimization;
       } else if ((this->*p)(i, b, cur_level)) {
         // C1-generated fully profiled code is about 30% slower than the limited profile
         // code that has only invocation and backedge counters. The observation is that
         // if C2 queue is large enough we can spend too much time in the fully profiled code
         // while waiting for C2 to pick the method from the queue. To alleviate this problem
         // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
         // we choose to compile a limited profiled version and then recompile with full profiling
         // when the load on C2 goes down.
         if (!disable_feedback && CompileBroker::queue_size(CompLevel_full_optimization) >
                                  Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
           next_level = CompLevel_limited_profile;
         } else {
           next_level = CompLevel_full_profile;
         }
       }
       break;
     case CompLevel_limited_profile:
       if (is_method_profiled(method)) {
         // Special case: we got here because this method was fully profiled in the interpreter.
         next_level = CompLevel_full_optimization;
       } else {
         MethodData* mdo = method->method_data();
         if (mdo != NULL) {
           if (mdo->would_profile()) {
             if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=
                                      Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
                                      (this->*p)(i, b, cur_level))) {
               next_level = CompLevel_full_profile;
             }
           } else {
             next_level = CompLevel_full_optimization;
           }
         }
       }
       break;
     case CompLevel_full_profile:
       {
         MethodData* mdo = method->method_data();
         if (mdo != NULL) {
           if (mdo->would_profile()) {
             int mdo_i = mdo->invocation_count_delta();
             int mdo_b = mdo->backedge_count_delta();
             if ((this->*p)(mdo_i, mdo_b, cur_level)) {
               next_level = CompLevel_full_optimization;
             }
           } else {
             next_level = CompLevel_full_optimization;
           }
         }
       }
       break;
     }
   }
   return MIN2(next_level, (CompLevel)TieredStopAtLevel);
 }

 // Determine if a method should be compiled with a normal entry point at a different level.
 CompLevel AdvancedThresholdPolicy::call_event(Method* method, CompLevel cur_level) {
   CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(),
                              common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true));
   CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);

   // If OSR method level is greater than the regular method level, the levels should be
   // equalized by raising the regular method level in order to avoid OSRs during each
   // invocation of the method.
   if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
     MethodData* mdo = method->method_data();
     guarantee(mdo != NULL, "MDO should not be NULL");
     if (mdo->invocation_count() >= 1) {
       next_level = CompLevel_full_optimization;
     }
   } else {
     next_level = MAX2(osr_level, next_level);
   }
   return next_level;
 }

 // Determine if we should do an OSR compilation of a given method.
 CompLevel AdvancedThresholdPolicy::loop_event(Method* method, CompLevel cur_level) {
   CompLevel next_level = common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true);
   if (cur_level == CompLevel_none) {
     // If there is a live OSR method that means that we deopted to the interpreter
     // for the transition.
     CompLevel osr_level = MIN2((CompLevel)method->highest_osr_comp_level(), next_level);
     if (osr_level > CompLevel_none) {
       return osr_level;
     }
   }
   return next_level;
 }

 // Update the rate and submit compile
 void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, JavaThread* thread) {
   int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
   update_rate(os::javaTimeMillis(), mh());
   CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", thread);
 }

 // Handle the invocation event.
 void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh,
                                                       CompLevel level, nmethod* nm, JavaThread* thread) {
   if (should_create_mdo(mh(), level)) {
     create_mdo(mh, thread);
   }
   if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh)) {
     CompLevel next_level = call_event(mh(), level);
     if (next_level != level) {
       compile(mh, InvocationEntryBci, next_level, thread);
     }
   }
 }

 // Handle the back branch event. Notice that we can compile the method
 // with a regular entry from here.
 void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh,
                                                        int bci, CompLevel level, nmethod* nm, JavaThread* thread) {
   if (should_create_mdo(mh(), level)) {
     create_mdo(mh, thread);
   }
   // Check if MDO should be created for the inlined method
   if (should_create_mdo(imh(), level)) {
     create_mdo(imh, thread);
   }

   if (is_compilation_enabled()) {
     CompLevel next_osr_level = loop_event(imh(), level);
     CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level();
     // At the very least compile the OSR version
     if (!CompileBroker::compilation_is_in_queue(imh) && (next_osr_level != level)) {
       compile(imh, bci, next_osr_level, thread);
     }

     // Use loop event as an opportunity to also check if there's been
     // enough calls.
     CompLevel cur_level, next_level;
     if (mh() != imh()) { // If there is an enclosing method
       guarantee(nm != NULL, "Should have nmethod here");
       cur_level = comp_level(mh());
       next_level = call_event(mh(), cur_level);

       if (max_osr_level == CompLevel_full_optimization) {
         // The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts
         bool make_not_entrant = false;
         if (nm->is_osr_method()) {
           // This is an osr method, just make it not entrant and recompile later if needed
           make_not_entrant = true;
         } else {
           if (next_level != CompLevel_full_optimization) {
             // next_level is not full opt, so we need to recompile the
             // enclosing method without the inlinee
             cur_level = CompLevel_none;
             make_not_entrant = true;
           }
         }
         if (make_not_entrant) {
           if (PrintTieredEvents) {
             int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci;
             print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level);
           }
           nm->make_not_entrant();
         }
       }
       if (!CompileBroker::compilation_is_in_queue(mh)) {
         // Fix up next_level if necessary to avoid deopts
         if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) {
           next_level = CompLevel_full_profile;
         }
         if (cur_level != next_level) {
           compile(mh, InvocationEntryBci, next_level, thread);
         }
       }
     } else {
       cur_level = comp_level(imh());
       next_level = call_event(imh(), cur_level);
       if (!CompileBroker::compilation_is_in_queue(imh) && (next_level != cur_level)) {
         compile(imh, InvocationEntryBci, next_level, thread);
       }
     }
   }
 }

 #endif // TIERED
	/*
	* Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*
	*/

	#include "precompiled.hpp"
	#include "runtime/advancedThresholdPolicy.hpp"
	#include "runtime/simpleThresholdPolicy.inline.hpp"

	#ifdef TIERED
	// Print an event.
	void AdvancedThresholdPolicy::print_specific(EventType type, methodHandle mh, methodHandle imh,
	int bci, CompLevel level) {
	tty->print(" rate=");
	if (mh->prev_time() == 0) tty->print("n/a");
	else tty->print("%f", mh->rate());

	tty->print(" k=%.2lf,%.2lf", threshold_scale(CompLevel_full_profile, Tier3LoadFeedback),
	threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));

	}

	void AdvancedThresholdPolicy::initialize() {
	// Turn on ergonomic compiler count selection
	if (FLAG_IS_DEFAULT(CICompilerCountPerCPU) && FLAG_IS_DEFAULT(CICompilerCount)) {
	FLAG_SET_DEFAULT(CICompilerCountPerCPU, true);
	}
	int count = CICompilerCount;
	if (CICompilerCountPerCPU) {
	// Simple log n seems to grow too slowly for tiered, try something faster: log n * log log n
	int log_cpu = log2_intptr(os::active_processor_count());
	int loglog_cpu = log2_intptr(MAX2(log_cpu, 1));
	count = MAX2(log_cpu * loglog_cpu, 1) * 3 / 2;
	}

	set_c1_count(MAX2(count / 3, 1));
	set_c2_count(MAX2(count - c1_count(), 1));
	FLAG_SET_ERGO(intx, CICompilerCount, c1_count() + c2_count());

	// Some inlining tuning
	#ifdef X86
	if (FLAG_IS_DEFAULT(InlineSmallCode)) {
	FLAG_SET_DEFAULT(InlineSmallCode, 2000);
	}
	#endif

	#ifdef SPARC
	if (FLAG_IS_DEFAULT(InlineSmallCode)) {
	FLAG_SET_DEFAULT(InlineSmallCode, 2500);
	}
	#endif

	set_increase_threshold_at_ratio();
	set_start_time(os::javaTimeMillis());
	}

	// update_rate() is called from select_task() while holding a compile queue lock.
	void AdvancedThresholdPolicy::update_rate(jlong t, Method* m) {
	// Skip update if counters are absent.
	// Can't allocate them since we are holding compile queue lock.
	if (m->method_counters() == NULL) return;

	if (is_old(m)) {
	// We don't remove old methods from the queue,
	// so we can just zero the rate.
	m->set_rate(0);
	return;
	}

	// We don't update the rate if we've just came out of a safepoint.
	// delta_s is the time since last safepoint in milliseconds.
	jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
	jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement
	// How many events were there since the last time?
	int event_count = m->invocation_count() + m->backedge_count();
	int delta_e = event_count - m->prev_event_count();

	// We should be running for at least 1ms.
	if (delta_s >= TieredRateUpdateMinTime) {
	// And we must've taken the previous point at least 1ms before.
	if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) {
	m->set_prev_time(t);
	m->set_prev_event_count(event_count);
	m->set_rate((float)delta_e / (float)delta_t); // Rate is events per millisecond
	} else {
	if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) {
	// If nothing happened for 25ms, zero the rate. Don't modify prev values.
	m->set_rate(0);
	}
	}
	}
	}

	// Check if this method has been stale from a given number of milliseconds.
	// See select_task().
	bool AdvancedThresholdPolicy::is_stale(jlong t, jlong timeout, Method* m) {
	jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
	jlong delta_t = t - m->prev_time();
	if (delta_t > timeout && delta_s > timeout) {
	int event_count = m->invocation_count() + m->backedge_count();
	int delta_e = event_count - m->prev_event_count();
	// Return true if there were no events.
	return delta_e == 0;
	}
	return false;
	}

	// We don't remove old methods from the compile queue even if they have
	// very low activity. See select_task().
	bool AdvancedThresholdPolicy::is_old(Method* method) {
	return method->invocation_count() > 50000 \|\| method->backedge_count() > 500000;
	}

	double AdvancedThresholdPolicy::weight(Method* method) {
	return (method->rate() + 1) * ((method->invocation_count() + 1) * (method->backedge_count() + 1));
	}

	// Apply heuristics and return true if x should be compiled before y
	bool AdvancedThresholdPolicy::compare_methods(Method* x, Method* y) {
	if (x->highest_comp_level() > y->highest_comp_level()) {
	// recompilation after deopt
	return true;
	} else
	if (x->highest_comp_level() == y->highest_comp_level()) {
	if (weight(x) > weight(y)) {
	return true;
	}
	}
	return false;
	}

	// Is method profiled enough?
	bool AdvancedThresholdPolicy::is_method_profiled(Method* method) {
	MethodData* mdo = method->method_data();
	if (mdo != NULL) {
	int i = mdo->invocation_count_delta();
	int b = mdo->backedge_count_delta();
	return call_predicate_helper<CompLevel_full_profile>(i, b, 1);
	}
	return false;
	}

	// Called with the queue locked and with at least one element
	CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {
	CompileTask *max_task = NULL;
	Method* max_method = NULL;
	jlong t = os::javaTimeMillis();
	// Iterate through the queue and find a method with a maximum rate.
	for (CompileTask* task = compile_queue->first(); task != NULL;) {
	CompileTask* next_task = task->next();
	Method* method = task->method();
	update_rate(t, method);
	if (max_task == NULL) {
	max_task = task;
	max_method = method;
	} else {
	// If a method has been stale for some time, remove it from the queue.
	if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) {
	if (PrintTieredEvents) {
	print_event(REMOVE_FROM_QUEUE, method, method, task->osr_bci(), (CompLevel)task->comp_level());
	}
	compile_queue->remove_and_mark_stale(task);
	method->clear_queued_for_compilation();
	task = next_task;
	continue;
	}

	// Select a method with a higher rate
	if (compare_methods(method, max_method)) {
	max_task = task;
	max_method = method;
	}
	}
	task = next_task;
	}

	if (max_task->comp_level() == CompLevel_full_profile && TieredStopAtLevel > CompLevel_full_profile
	&& is_method_profiled(max_method)) {
	max_task->set_comp_level(CompLevel_limited_profile);
	if (PrintTieredEvents) {
	print_event(UPDATE_IN_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
	}
	}

	return max_task;
	}

	double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
	double queue_size = CompileBroker::queue_size(level);
	int comp_count = compiler_count(level);
	double k = queue_size / (feedback_k * comp_count) + 1;

	// Increase C1 compile threshold when the code cache is filled more
	// than specified by IncreaseFirstTierCompileThresholdAt percentage.
	// The main intention is to keep enough free space for C2 compiled code
	// to achieve peak performance if the code cache is under stress.
	if ((TieredStopAtLevel == CompLevel_full_optimization) && (level != CompLevel_full_optimization)) {
	double current_reverse_free_ratio = CodeCache::reverse_free_ratio();
	if (current_reverse_free_ratio > _increase_threshold_at_ratio) {
	k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio);
	}
	}
	return k;
	}

	// Call and loop predicates determine whether a transition to a higher
	// compilation level should be performed (pointers to predicate functions
	// are passed to common()).
	// Tier?LoadFeedback is basically a coefficient that determines of
	// how many methods per compiler thread can be in the queue before
	// the threshold values double.
	bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level) {
	switch(cur_level) {
	case CompLevel_none:
	case CompLevel_limited_profile: {
	double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
	return loop_predicate_helper<CompLevel_none>(i, b, k);
	}
	case CompLevel_full_profile: {
	double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
	return loop_predicate_helper<CompLevel_full_profile>(i, b, k);
	}
	default:
	return true;
	}
	}

	bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level) {
	switch(cur_level) {
	case CompLevel_none:
	case CompLevel_limited_profile: {
	double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
	return call_predicate_helper<CompLevel_none>(i, b, k);
	}
	case CompLevel_full_profile: {
	double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
	return call_predicate_helper<CompLevel_full_profile>(i, b, k);
	}
	default:
	return true;
	}
	}

	// If a method is old enough and is still in the interpreter we would want to
	// start profiling without waiting for the compiled method to arrive.
	// We also take the load on compilers into the account.
	bool AdvancedThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) {
	if (cur_level == CompLevel_none &&
	CompileBroker::queue_size(CompLevel_full_optimization) <=
	Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
	int i = method->invocation_count();
	int b = method->backedge_count();
	double k = Tier0ProfilingStartPercentage / 100.0;
	return call_predicate_helper<CompLevel_none>(i, b, k) \|\| loop_predicate_helper<CompLevel_none>(i, b, k);
	}
	return false;
	}

	// Inlining control: if we're compiling a profiled method with C1 and the callee
	// is known to have OSRed in a C2 version, don't inline it.
	bool AdvancedThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) {
	CompLevel comp_level = (CompLevel)env->comp_level();
	if (comp_level == CompLevel_full_profile \|\|
	comp_level == CompLevel_limited_profile) {
	return callee->highest_osr_comp_level() == CompLevel_full_optimization;
	}
	return false;
	}

	// Create MDO if necessary.
	void AdvancedThresholdPolicy::create_mdo(methodHandle mh, JavaThread* THREAD) {
	if (mh->is_native() \|\| mh->is_abstract() \|\| mh->is_accessor()) return;
	if (mh->method_data() == NULL) {
	Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR);
	}
	}


	/*
	* Method states:
	* 0 - interpreter (CompLevel_none)
	* 1 - pure C1 (CompLevel_simple)
	* 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
	* 3 - C1 with full profiling (CompLevel_full_profile)
	* 4 - C2 (CompLevel_full_optimization)
	*
	* Common state transition patterns:
	* a. 0 -> 3 -> 4.
	* The most common path. But note that even in this straightforward case
	* profiling can start at level 0 and finish at level 3.
	*
	* b. 0 -> 2 -> 3 -> 4.
	* This case occures when the load on C2 is deemed too high. So, instead of transitioning
	* into state 3 directly and over-profiling while a method is in the C2 queue we transition to
	* level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
	*
	* c. 0 -> (3->2) -> 4.
	* In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
	* to enable the profiling to fully occur at level 0. In this case we change the compilation level
	* of the method to 2 while the request is still in-queue, because it'll allow it to run much faster
	* without full profiling while c2 is compiling.
	*
	* d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
	* After a method was once compiled with C1 it can be identified as trivial and be compiled to
	* level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
	*
	* e. 0 -> 4.
	* This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
	* or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
	* the compiled version already exists).
	*
	* Note that since state 0 can be reached from any other state via deoptimization different loops
	* are possible.
	*
	*/

	// Common transition function. Given a predicate determines if a method should transition to another level.
	CompLevel AdvancedThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) {
	CompLevel next_level = cur_level;
	int i = method->invocation_count();
	int b = method->backedge_count();

	if (is_trivial(method)) {
	next_level = CompLevel_simple;
	} else {
	switch(cur_level) {
	case CompLevel_none:
	// If we were at full profile level, would we switch to full opt?
	if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) {
	next_level = CompLevel_full_optimization;
	} else if ((this->*p)(i, b, cur_level)) {
	// C1-generated fully profiled code is about 30% slower than the limited profile
	// code that has only invocation and backedge counters. The observation is that
	// if C2 queue is large enough we can spend too much time in the fully profiled code
	// while waiting for C2 to pick the method from the queue. To alleviate this problem
	// we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
	// we choose to compile a limited profiled version and then recompile with full profiling
	// when the load on C2 goes down.
	if (!disable_feedback && CompileBroker::queue_size(CompLevel_full_optimization) >
	Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
	next_level = CompLevel_limited_profile;
	} else {
	next_level = CompLevel_full_profile;
	}
	}
	break;
	case CompLevel_limited_profile:
	if (is_method_profiled(method)) {
	// Special case: we got here because this method was fully profiled in the interpreter.
	next_level = CompLevel_full_optimization;
	} else {
	MethodData* mdo = method->method_data();
	if (mdo != NULL) {
	if (mdo->would_profile()) {
	if (disable_feedback \|\| (CompileBroker::queue_size(CompLevel_full_optimization) <=
	Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
	(this->*p)(i, b, cur_level))) {
	next_level = CompLevel_full_profile;
	}
	} else {
	next_level = CompLevel_full_optimization;
	}
	}
	}
	break;
	case CompLevel_full_profile:
	{
	MethodData* mdo = method->method_data();
	if (mdo != NULL) {
	if (mdo->would_profile()) {
	int mdo_i = mdo->invocation_count_delta();
	int mdo_b = mdo->backedge_count_delta();
	if ((this->*p)(mdo_i, mdo_b, cur_level)) {
	next_level = CompLevel_full_optimization;
	}
	} else {
	next_level = CompLevel_full_optimization;
	}
	}
	}
	break;
	}
	}
	return MIN2(next_level, (CompLevel)TieredStopAtLevel);
	}

	// Determine if a method should be compiled with a normal entry point at a different level.
	CompLevel AdvancedThresholdPolicy::call_event(Method* method, CompLevel cur_level) {
	CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(),
	common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true));
	CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);

	// If OSR method level is greater than the regular method level, the levels should be
	// equalized by raising the regular method level in order to avoid OSRs during each
	// invocation of the method.
	if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
	MethodData* mdo = method->method_data();
	guarantee(mdo != NULL, "MDO should not be NULL");
	if (mdo->invocation_count() >= 1) {
	next_level = CompLevel_full_optimization;
	}
	} else {
	next_level = MAX2(osr_level, next_level);
	}
	return next_level;
	}

	// Determine if we should do an OSR compilation of a given method.
	CompLevel AdvancedThresholdPolicy::loop_event(Method* method, CompLevel cur_level) {
	CompLevel next_level = common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true);
	if (cur_level == CompLevel_none) {
	// If there is a live OSR method that means that we deopted to the interpreter
	// for the transition.
	CompLevel osr_level = MIN2((CompLevel)method->highest_osr_comp_level(), next_level);
	if (osr_level > CompLevel_none) {
	return osr_level;
	}
	}
	return next_level;
	}

	// Update the rate and submit compile
	void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, JavaThread* thread) {
	int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
	update_rate(os::javaTimeMillis(), mh());
	CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", thread);
	}

	// Handle the invocation event.
	void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh,
	CompLevel level, nmethod* nm, JavaThread* thread) {
	if (should_create_mdo(mh(), level)) {
	create_mdo(mh, thread);
	}
	if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh)) {
	CompLevel next_level = call_event(mh(), level);
	if (next_level != level) {
	compile(mh, InvocationEntryBci, next_level, thread);
	}
	}
	}

	// Handle the back branch event. Notice that we can compile the method
	// with a regular entry from here.
	void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh,
	int bci, CompLevel level, nmethod* nm, JavaThread* thread) {
	if (should_create_mdo(mh(), level)) {
	create_mdo(mh, thread);
	}
	// Check if MDO should be created for the inlined method
	if (should_create_mdo(imh(), level)) {
	create_mdo(imh, thread);
	}

	if (is_compilation_enabled()) {
	CompLevel next_osr_level = loop_event(imh(), level);
	CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level();
	// At the very least compile the OSR version
	if (!CompileBroker::compilation_is_in_queue(imh) && (next_osr_level != level)) {
	compile(imh, bci, next_osr_level, thread);
	}

	// Use loop event as an opportunity to also check if there's been
	// enough calls.
	CompLevel cur_level, next_level;
	if (mh() != imh()) { // If there is an enclosing method
	guarantee(nm != NULL, "Should have nmethod here");
	cur_level = comp_level(mh());
	next_level = call_event(mh(), cur_level);

	if (max_osr_level == CompLevel_full_optimization) {
	// The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts
	bool make_not_entrant = false;
	if (nm->is_osr_method()) {
	// This is an osr method, just make it not entrant and recompile later if needed
	make_not_entrant = true;
	} else {
	if (next_level != CompLevel_full_optimization) {
	// next_level is not full opt, so we need to recompile the
	// enclosing method without the inlinee
	cur_level = CompLevel_none;
	make_not_entrant = true;
	}
	}
	if (make_not_entrant) {
	if (PrintTieredEvents) {
	int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci;
	print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level);
	}
	nm->make_not_entrant();
	}
	}
	if (!CompileBroker::compilation_is_in_queue(mh)) {
	// Fix up next_level if necessary to avoid deopts
	if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) {
	next_level = CompLevel_full_profile;
	}
	if (cur_level != next_level) {
	compile(mh, InvocationEntryBci, next_level, thread);
	}
	}
	} else {
	cur_level = comp_level(imh());
	next_level = call_event(imh(), cur_level);
	if (!CompileBroker::compilation_is_in_queue(imh) && (next_level != cur_level)) {
	compile(imh, InvocationEntryBci, next_level, thread);
	}
	}
	}
	}

	#endif // TIERED