diff -r 496bbf554c5c -r 38176d1c5ec2 src/hotspot/share/runtime/tieredThresholdPolicy.hpp --- a/src/hotspot/share/runtime/tieredThresholdPolicy.hpp Wed Oct 16 01:16:12 2019 +0200 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,278 +0,0 @@ -/* - * Copyright (c) 2010, 2019, 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. - * - */ - -#ifndef SHARE_RUNTIME_TIEREDTHRESHOLDPOLICY_HPP -#define SHARE_RUNTIME_TIEREDTHRESHOLDPOLICY_HPP - -#include "code/nmethod.hpp" -#include "oops/methodData.hpp" -#include "runtime/compilationPolicy.hpp" -#include "utilities/globalDefinitions.hpp" - -#ifdef TIERED - -class CompileTask; -class CompileQueue; -/* - * The system supports 5 execution levels: - * * level 0 - interpreter - * * level 1 - C1 with full optimization (no profiling) - * * level 2 - C1 with invocation and backedge counters - * * level 3 - C1 with full profiling (level 2 + MDO) - * * level 4 - C2 - * - * Levels 0, 2 and 3 periodically notify the runtime about the current value of the counters - * (invocation counters and backedge counters). The frequency of these notifications is - * different at each level. These notifications are used by the policy to decide what transition - * to make. - * - * Execution starts at level 0 (interpreter), then the policy can decide either to compile the - * method at level 3 or level 2. The decision is based on the following factors: - * 1. The length of the C2 queue determines the next level. The observation is that level 2 - * is generally faster than level 3 by about 30%, therefore we would want to minimize the time - * a method spends at level 3. We should only spend the time at level 3 that is necessary to get - * adequate profiling. So, if the C2 queue is long enough it is more beneficial to go first to - * level 2, because if we transitioned to level 3 we would be stuck there until our C2 compile - * request makes its way through the long queue. When the load on C2 recedes we are going to - * recompile at level 3 and start gathering profiling information. - * 2. The length of C1 queue is used to dynamically adjust the thresholds, so as to introduce - * additional filtering if the compiler is overloaded. The rationale is that by the time a - * method gets compiled it can become unused, so it doesn't make sense to put too much onto the - * queue. - * - * After profiling is completed at level 3 the transition is made to level 4. Again, the length - * of the C2 queue is used as a feedback to adjust the thresholds. - * - * After the first C1 compile some basic information is determined about the code like the number - * of the blocks and the number of the loops. Based on that it can be decided that a method - * is trivial and compiling it with C1 will yield the same code. In this case the method is - * compiled at level 1 instead of 4. - * - * We also support profiling at level 0. If C1 is slow enough to produce the level 3 version of - * the code and the C2 queue is sufficiently small we can decide to start profiling in the - * interpreter (and continue profiling in the compiled code once the level 3 version arrives). - * If the profiling at level 0 is fully completed before level 3 version is produced, a level 2 - * version is compiled instead in order to run faster waiting for a level 4 version. - * - * Compile queues are implemented as priority queues - for each method in the queue we compute - * the event rate (the number of invocation and backedge counter increments per unit of time). - * When getting an element off the queue we pick the one with the largest rate. Maintaining the - * rate also allows us to remove stale methods (the ones that got on the queue but stopped - * being used shortly after that). -*/ - -/* Command line options: - * - Tier?InvokeNotifyFreqLog and Tier?BackedgeNotifyFreqLog control the frequency of method - * invocation and backedge notifications. Basically every n-th invocation or backedge a mutator thread - * makes a call into the runtime. - * - * - Tier?InvocationThreshold, Tier?CompileThreshold, Tier?BackEdgeThreshold, Tier?MinInvocationThreshold control - * compilation thresholds. - * Level 2 thresholds are not used and are provided for option-compatibility and potential future use. - * Other thresholds work as follows: - * - * Transition from interpreter (level 0) to C1 with full profiling (level 3) happens when - * the following predicate is true (X is the level): - * - * i > TierXInvocationThreshold * s || (i > TierXMinInvocationThreshold * s && i + b > TierXCompileThreshold * s), - * - * where $i$ is the number of method invocations, $b$ number of backedges and $s$ is the scaling - * coefficient that will be discussed further. - * The intuition is to equalize the time that is spend profiling each method. - * The same predicate is used to control the transition from level 3 to level 4 (C2). It should be - * noted though that the thresholds are relative. Moreover i and b for the 0->3 transition come - * from Method* and for 3->4 transition they come from MDO (since profiled invocations are - * counted separately). Finally, if a method does not contain anything worth profiling, a transition - * from level 3 to level 4 occurs without considering thresholds (e.g., with fewer invocations than - * what is specified by Tier4InvocationThreshold). - * - * OSR transitions are controlled simply with b > TierXBackEdgeThreshold * s predicates. - * - * - Tier?LoadFeedback options are used to automatically scale the predicates described above depending - * on the compiler load. The scaling coefficients are computed as follows: - * - * s = queue_size_X / (TierXLoadFeedback * compiler_count_X) + 1, - * - * where queue_size_X is the current size of the compiler queue of level X, and compiler_count_X - * is the number of level X compiler threads. - * - * Basically these parameters describe how many methods should be in the compile queue - * per compiler thread before the scaling coefficient increases by one. - * - * This feedback provides the mechanism to automatically control the flow of compilation requests - * depending on the machine speed, mutator load and other external factors. - * - * - Tier3DelayOn and Tier3DelayOff parameters control another important feedback loop. - * Consider the following observation: a method compiled with full profiling (level 3) - * is about 30% slower than a method at level 2 (just invocation and backedge counters, no MDO). - * Normally, the following transitions will occur: 0->3->4. The problem arises when the C2 queue - * gets congested and the 3->4 transition is delayed. While the method is the C2 queue it continues - * executing at level 3 for much longer time than is required by the predicate and at suboptimal speed. - * The idea is to dynamically change the behavior of the system in such a way that if a substantial - * load on C2 is detected we would first do the 0->2 transition allowing a method to run faster. - * And then when the load decreases to allow 2->3 transitions. - * - * Tier3Delay* parameters control this switching mechanism. - * Tier3DelayOn is the number of methods in the C2 queue per compiler thread after which the policy - * no longer does 0->3 transitions but does 0->2 transitions instead. - * Tier3DelayOff switches the original behavior back when the number of methods in the C2 queue - * per compiler thread falls below the specified amount. - * The hysteresis is necessary to avoid jitter. - * - * - TieredCompileTaskTimeout is the amount of time an idle method can spend in the compile queue. - * Basically, since we use the event rate d(i + b)/dt as a value of priority when selecting a method to - * compile from the compile queue, we also can detect stale methods for which the rate has been - * 0 for some time in the same iteration. Stale methods can appear in the queue when an application - * abruptly changes its behavior. - * - * - TieredStopAtLevel, is used mostly for testing. It allows to bypass the policy logic and stick - * to a given level. For example it's useful to set TieredStopAtLevel = 1 in order to compile everything - * with pure c1. - * - * - Tier0ProfilingStartPercentage allows the interpreter to start profiling when the inequalities in the - * 0->3 predicate are already exceeded by the given percentage but the level 3 version of the - * method is still not ready. We can even go directly from level 0 to 4 if c1 doesn't produce a compiled - * version in time. This reduces the overall transition to level 4 and decreases the startup time. - * Note that this behavior is also guarded by the Tier3Delay mechanism: when the c2 queue is too long - * these is not reason to start profiling prematurely. - * - * - TieredRateUpdateMinTime and TieredRateUpdateMaxTime are parameters of the rate computation. - * Basically, the rate is not computed more frequently than TieredRateUpdateMinTime and is considered - * to be zero if no events occurred in TieredRateUpdateMaxTime. - */ - -class TieredThresholdPolicy : public CompilationPolicy { - jlong _start_time; - int _c1_count, _c2_count; - - // Check if the counter is big enough and set carry (effectively infinity). - inline void set_carry_if_necessary(InvocationCounter *counter); - // Set carry flags in the counters (in Method* and MDO). - inline void handle_counter_overflow(Method* method); - // Call and loop predicates determine whether a transition to a higher compilation - // level should be performed (pointers to predicate functions are passed to common_TF(). - // Predicates also take compiler load into account. - typedef bool (TieredThresholdPolicy::*Predicate)(int i, int b, CompLevel cur_level, Method* method); - bool call_predicate(int i, int b, CompLevel cur_level, Method* method); - bool loop_predicate(int i, int b, CompLevel cur_level, Method* method); - // Common transition function. Given a predicate determines if a method should transition to another level. - CompLevel common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback = false); - // Transition functions. - // call_event determines if a method should be compiled at a different - // level with a regular invocation entry. - CompLevel call_event(Method* method, CompLevel cur_level, JavaThread* thread); - // loop_event checks if a method should be OSR compiled at a different - // level. - CompLevel loop_event(Method* method, CompLevel cur_level, JavaThread* thread); - void print_counters(const char* prefix, const methodHandle& mh); - // Has a method been long around? - // We don't remove old methods from the compile queue even if they have - // very low activity (see select_task()). - inline bool is_old(Method* method); - // Was a given method inactive for a given number of milliseconds. - // If it is, we would remove it from the queue (see select_task()). - inline bool is_stale(jlong t, jlong timeout, Method* m); - // Compute the weight of the method for the compilation scheduling - inline double weight(Method* method); - // Apply heuristics and return true if x should be compiled before y - inline bool compare_methods(Method* x, Method* y); - // Compute event rate for a given method. The rate is the number of event (invocations + backedges) - // per millisecond. - inline void update_rate(jlong t, Method* m); - // Compute threshold scaling coefficient - inline double threshold_scale(CompLevel level, int feedback_k); - // 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. This function - // determines whether we should do that. - inline bool should_create_mdo(Method* method, CompLevel cur_level); - // Create MDO if necessary. - void create_mdo(const methodHandle& mh, JavaThread* thread); - // Is method profiled enough? - bool is_method_profiled(Method* method); - - double _increase_threshold_at_ratio; - - bool maybe_switch_to_aot(const methodHandle& mh, CompLevel cur_level, CompLevel next_level, JavaThread* thread); - - int c1_count() const { return _c1_count; } - int c2_count() const { return _c2_count; } - void set_c1_count(int x) { _c1_count = x; } - void set_c2_count(int x) { _c2_count = x; } - - enum EventType { CALL, LOOP, COMPILE, REMOVE_FROM_QUEUE, UPDATE_IN_QUEUE, REPROFILE, MAKE_NOT_ENTRANT }; - void print_event(EventType type, const methodHandle& mh, const methodHandle& imh, int bci, CompLevel level); - // Print policy-specific information if necessary - void print_specific(EventType type, const methodHandle& mh, const methodHandle& imh, int bci, CompLevel level); - // Check if the method can be compiled, change level if necessary - void compile(const methodHandle& mh, int bci, CompLevel level, JavaThread* thread); - // Submit a given method for compilation - void submit_compile(const methodHandle& mh, int bci, CompLevel level, JavaThread* thread); - // Simple methods are as good being compiled with C1 as C2. - // This function tells if it's such a function. - inline static bool is_trivial(Method* method); - // Force method to be compiled at CompLevel_simple? - inline static bool should_compile_at_level_simple(Method* method); - - // Predicate helpers are used by .*_predicate() methods as well as others. - // They check the given counter values, multiplied by the scale against the thresholds. - template static inline bool call_predicate_helper(int i, int b, double scale, Method* method); - template static inline bool loop_predicate_helper(int i, int b, double scale, Method* method); - - // Get a compilation level for a given method. - static CompLevel comp_level(Method* method); - void method_invocation_event(const methodHandle& method, const methodHandle& inlinee, - CompLevel level, CompiledMethod* nm, JavaThread* thread); - void method_back_branch_event(const methodHandle& method, const methodHandle& inlinee, - int bci, CompLevel level, CompiledMethod* nm, JavaThread* thread); - - void set_increase_threshold_at_ratio() { _increase_threshold_at_ratio = 100 / (100 - (double)IncreaseFirstTierCompileThresholdAt); } - void set_start_time(jlong t) { _start_time = t; } - jlong start_time() const { return _start_time; } - -public: - TieredThresholdPolicy() : _start_time(0), _c1_count(0), _c2_count(0) { } - virtual int compiler_count(CompLevel comp_level) { - if (is_c1_compile(comp_level)) return c1_count(); - if (is_c2_compile(comp_level)) return c2_count(); - return 0; - } - virtual CompLevel initial_compile_level() { return MIN2((CompLevel)TieredStopAtLevel, CompLevel_initial_compile); } - virtual void do_safepoint_work() { } - virtual void delay_compilation(Method* method) { } - virtual void disable_compilation(Method* method) { } - virtual void reprofile(ScopeDesc* trap_scope, bool is_osr); - virtual nmethod* event(const methodHandle& method, const methodHandle& inlinee, - int branch_bci, int bci, CompLevel comp_level, CompiledMethod* nm, JavaThread* thread); - // Select task is called by CompileBroker. We should return a task or NULL. - virtual CompileTask* select_task(CompileQueue* compile_queue); - // Tell the runtime if we think a given method is adequately profiled. - virtual bool is_mature(Method* method); - // Initialize: set compiler thread count - virtual void initialize(); - virtual bool should_not_inline(ciEnv* env, ciMethod* callee); -}; - -#endif // TIERED - -#endif // SHARE_RUNTIME_TIEREDTHRESHOLDPOLICY_HPP