/* * 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(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(i, b, k); } case CompLevel_full_profile: { double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback); return loop_predicate_helper(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(i, b, k); } case CompLevel_full_profile: { double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback); return call_predicate_helper(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(i, b, k) || loop_predicate_helper(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, 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