提交 e2d29af9 编写于 作者: I iveresov

7020403: Add AdvancedCompilationPolicy for tiered

Summary: This implements adaptive tiered compilation policy.
Reviewed-by: kvn, never
上级 fed0a1ba
......@@ -103,6 +103,12 @@ methodOop methodKlass::allocate(constMethodHandle xconst,
m->backedge_counter()->init();
m->clear_number_of_breakpoints();
#ifdef TIERED
m->set_rate(0);
m->set_prev_event_count(0);
m->set_prev_time(0);
#endif
assert(m->is_parsable(), "must be parsable here.");
assert(m->size() == size, "wrong size for object");
// We should not publish an uprasable object's reference
......
......@@ -84,6 +84,11 @@
// | invocation_counter |
// | backedge_counter |
// |------------------------------------------------------|
// | prev_time (tiered only, 64 bit wide) |
// | |
// |------------------------------------------------------|
// | rate (tiered) |
// |------------------------------------------------------|
// | code (pointer) |
// | i2i (pointer) |
// | adapter (pointer) |
......@@ -124,6 +129,11 @@ class methodOopDesc : public oopDesc {
InvocationCounter _invocation_counter; // Incremented before each activation of the method - used to trigger frequency-based optimizations
InvocationCounter _backedge_counter; // Incremented before each backedge taken - used to trigger frequencey-based optimizations
#ifdef TIERED
jlong _prev_time; // Previous time the rate was acquired
float _rate; // Events (invocation and backedge counter increments) per millisecond
#endif
#ifndef PRODUCT
int _compiled_invocation_count; // Number of nmethod invocations so far (for perf. debugging)
#endif
......@@ -304,6 +314,17 @@ class methodOopDesc : public oopDesc {
InvocationCounter* invocation_counter() { return &_invocation_counter; }
InvocationCounter* backedge_counter() { return &_backedge_counter; }
#ifdef TIERED
// We are reusing interpreter_invocation_count as a holder for the previous event count!
// We can do that since interpreter_invocation_count is not used in tiered.
int prev_event_count() const { return _interpreter_invocation_count; }
void set_prev_event_count(int count) { _interpreter_invocation_count = count; }
jlong prev_time() const { return _prev_time; }
void set_prev_time(jlong time) { _prev_time = time; }
float rate() const { return _rate; }
void set_rate(float rate) { _rate = rate; }
#endif
int invocation_count();
int backedge_count();
......
/*
* Copyright (c) 2010, 2011 Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
#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 - count / 3, 1));
// 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_start_time(os::javaTimeMillis());
}
// update_rate() is called from select_task() while holding a compile queue lock.
void AdvancedThresholdPolicy::update_rate(jlong t, methodOop m) {
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, methodOop 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(methodOop method) {
return method->invocation_count() > 50000 || method->backedge_count() > 500000;
}
double AdvancedThresholdPolicy::weight(methodOop 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(methodOop x, methodOop 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(methodOop method) {
methodDataOop 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;
methodOop max_method;
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();
methodOop method = (methodOop)JNIHandles::resolve(task->method_handle());
methodDataOop mdo = method->method_data();
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(KILL, method, method, task->osr_bci(), (CompLevel)task->comp_level());
}
CompileTaskWrapper ctw(task); // Frees the task
compile_queue->remove(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 && is_method_profiled(max_method)) {
max_task->set_comp_level(CompLevel_limited_profile);
if (PrintTieredEvents) {
print_event(UPDATE, 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;
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(methodOop 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;
}
// Create MDO if necessary.
void AdvancedThresholdPolicy::create_mdo(methodHandle mh, TRAPS) {
if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return;
if (mh->method_data() == NULL) {
methodOopDesc::build_interpreter_method_data(mh, THREAD);
if (HAS_PENDING_EXCEPTION) {
CLEAR_PENDING_EXCEPTION;
}
}
}
/*
* 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, methodOop method, CompLevel cur_level) {
if (is_trivial(method)) return CompLevel_simple;
CompLevel next_level = cur_level;
int i = method->invocation_count();
int b = method->backedge_count();
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) == 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 (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 {
methodDataOop mdo = method->method_data();
if (mdo != NULL) {
if (mdo->would_profile()) {
if (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:
{
methodDataOop 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 next_level;
}
// Determine if a method should be compiled with a normal entry point at a different level.
CompLevel AdvancedThresholdPolicy::call_event(methodOop method, CompLevel cur_level) {
CompLevel osr_level = (CompLevel) method->highest_osr_comp_level();
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) {
methodDataOop 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(methodOop method, CompLevel cur_level) {
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 = (CompLevel)method->highest_osr_comp_level();
if (osr_level > CompLevel_none) {
return osr_level;
}
}
return common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level);
}
// Update the rate and submit compile
void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, TRAPS) {
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, TRAPS) {
if (should_create_mdo(mh(), level)) {
create_mdo(mh, THREAD);
}
if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, InvocationEntryBci)) {
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, TRAPS) {
if (should_create_mdo(mh(), level)) {
create_mdo(mh, THREAD);
}
// If the method is already compiling, quickly bail out.
if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, bci)) {
// Use loop event as an opportinity to also check there's been
// enough calls.
CompLevel cur_level = comp_level(mh());
CompLevel next_level = call_event(mh(), cur_level);
CompLevel next_osr_level = loop_event(mh(), level);
if (next_osr_level == CompLevel_limited_profile) {
next_osr_level = CompLevel_full_profile; // OSRs are supposed to be for very hot methods.
}
next_level = MAX2(next_level,
next_osr_level < CompLevel_full_optimization ? next_osr_level : cur_level);
bool is_compiling = false;
if (next_level != cur_level) {
compile(mh, InvocationEntryBci, next_level, THREAD);
is_compiling = true;
}
// Do the OSR version
if (!is_compiling && next_osr_level != level) {
compile(mh, bci, next_osr_level, THREAD);
}
}
}
#endif // TIERED
/*
* Copyright (c) 2010, 2011 Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
#ifndef SHARE_VM_RUNTIME_ADVANCEDTHRESHOLDPOLICY_HPP
#define SHARE_VM_RUNTIME_ADVANCEDTHRESHOLDPOLICY_HPP
#include "runtime/simpleThresholdPolicy.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?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 methodOop and for 3->4 transition they come from MDO (since profiled invocations are
* counted separately).
*
* 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 AdvancedThresholdPolicy : public SimpleThresholdPolicy {
jlong _start_time;
// Call and loop predicates determine whether a transition to a higher compilation
// level should be performed (pointers to predicate functions are passed to common().
// Predicates also take compiler load into account.
typedef bool (AdvancedThresholdPolicy::*Predicate)(int i, int b, CompLevel cur_level);
bool call_predicate(int i, int b, CompLevel cur_level);
bool loop_predicate(int i, int b, CompLevel cur_level);
// Common transition function. Given a predicate determines if a method should transition to another level.
CompLevel common(Predicate p, methodOop method, CompLevel cur_level);
// Transition functions.
// call_event determines if a method should be compiled at a different
// level with a regular invocation entry.
CompLevel call_event(methodOop method, CompLevel cur_level);
// loop_event checks if a method should be OSR compiled at a different
// level.
CompLevel loop_event(methodOop method, CompLevel cur_level);
// 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(methodOop 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, methodOop m);
// Compute the weight of the method for the compilation scheduling
inline double weight(methodOop method);
// Apply heuristics and return true if x should be compiled before y
inline bool compare_methods(methodOop x, methodOop 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, methodOop 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(methodOop method, CompLevel cur_level);
// Create MDO if necessary.
void create_mdo(methodHandle mh, TRAPS);
// Is method profiled enough?
bool is_method_profiled(methodOop method);
protected:
void print_specific(EventType type, methodHandle mh, methodHandle imh, int bci, CompLevel level);
void set_start_time(jlong t) { _start_time = t; }
jlong start_time() const { return _start_time; }
// Submit a given method for compilation (and update the rate).
virtual void submit_compile(methodHandle mh, int bci, CompLevel level, TRAPS);
// event() from SimpleThresholdPolicy would call these.
virtual void method_invocation_event(methodHandle method, methodHandle inlinee,
CompLevel level, TRAPS);
virtual void method_back_branch_event(methodHandle method, methodHandle inlinee,
int bci, CompLevel level, TRAPS);
public:
AdvancedThresholdPolicy() : _start_time(0) { }
// Select task is called by CompileBroker. We should return a task or NULL.
virtual CompileTask* select_task(CompileQueue* compile_queue);
virtual void initialize();
};
#endif // TIERED
#endif // SHARE_VM_RUNTIME_ADVANCEDTHRESHOLDPOLICY_HPP
......@@ -1026,8 +1026,9 @@ void Arguments::check_compressed_oops_compat() {
}
void Arguments::set_tiered_flags() {
// With tiered, set default policy to AdvancedThresholdPolicy, which is 3.
if (FLAG_IS_DEFAULT(CompilationPolicyChoice)) {
FLAG_SET_DEFAULT(CompilationPolicyChoice, 2);
FLAG_SET_DEFAULT(CompilationPolicyChoice, 3);
}
if (CompilationPolicyChoice < 2) {
vm_exit_during_initialization(
......
/*
* Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2000, 2011, 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
......@@ -32,6 +32,7 @@
#include "oops/methodOop.hpp"
#include "oops/oop.inline.hpp"
#include "prims/nativeLookup.hpp"
#include "runtime/advancedThresholdPolicy.hpp"
#include "runtime/compilationPolicy.hpp"
#include "runtime/frame.hpp"
#include "runtime/handles.inline.hpp"
......@@ -70,10 +71,17 @@ void compilationPolicy_init() {
CompilationPolicy::set_policy(new SimpleThresholdPolicy());
#else
Unimplemented();
#endif
break;
case 3:
#ifdef TIERED
CompilationPolicy::set_policy(new AdvancedThresholdPolicy());
#else
Unimplemented();
#endif
break;
default:
fatal("CompilationPolicyChoice must be in the range: [0-2]");
fatal("CompilationPolicyChoice must be in the range: [0-3]");
}
CompilationPolicy::policy()->initialize();
}
......
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