root/src/runtime-profiler.cc
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DEFINITIONS
This source file includes following definitions.
- code_generated_
- GlobalSetUp
- GetICCounts
- Optimize
- AttemptOnStackReplacement
- ClearSampleBuffer
- LookupSample
- AddSample
- OptimizeNow
- NotifyTick
- SetUp
- Reset
- TearDown
- SamplerWindowSize
- UpdateSamplesAfterScavenge
- HandleWakeUp
- IsSomeIsolateInJS
- WaitForSomeIsolateToEnterJS
- StopRuntimeProfilerThreadBeforeShutdown
- RemoveDeadSamples
- UpdateSamplesAfterCompact
- SuspendIfNecessary
// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "v8.h"
#include "runtime-profiler.h"
#include "assembler.h"
#include "code-stubs.h"
#include "compilation-cache.h"
#include "deoptimizer.h"
#include "execution.h"
#include "global-handles.h"
#include "isolate-inl.h"
#include "mark-compact.h"
#include "platform.h"
#include "scopeinfo.h"
namespace v8 {
namespace internal {
// Optimization sampler constants.
static const int kSamplerFrameCount = 2;
// Constants for statistical profiler.
static const int kSamplerFrameWeight[kSamplerFrameCount] = { 2, 1 };
static const int kSamplerTicksBetweenThresholdAdjustment = 32;
static const int kSamplerThresholdInit = 3;
static const int kSamplerThresholdMin = 1;
static const int kSamplerThresholdDelta = 1;
static const int kSamplerThresholdSizeFactorInit = 3;
static const int kSizeLimit = 1500;
// Constants for counter based profiler.
// Number of times a function has to be seen on the stack before it is
// optimized.
static const int kProfilerTicksBeforeOptimization = 2;
// If the function optimization was disabled due to high deoptimization count,
// but the function is hot and has been seen on the stack this number of times,
// then we try to reenable optimization for this function.
static const int kProfilerTicksBeforeReenablingOptimization = 250;
// If a function does not have enough type info (according to
// FLAG_type_info_threshold), but has seen a huge number of ticks,
// optimize it as it is.
static const int kTicksWhenNotEnoughTypeInfo = 100;
// We only have one byte to store the number of ticks.
STATIC_ASSERT(kProfilerTicksBeforeOptimization < 256);
STATIC_ASSERT(kProfilerTicksBeforeReenablingOptimization < 256);
STATIC_ASSERT(kTicksWhenNotEnoughTypeInfo < 256);
// Maximum size in bytes of generated code for a function to be optimized
// the very first time it is seen on the stack.
static const int kMaxSizeEarlyOpt = 500;
Atomic32 RuntimeProfiler::state_ = 0;
// TODO(isolates): Clean up the semaphore when it is no longer required.
static LazySemaphore<0>::type semaphore = LAZY_SEMAPHORE_INITIALIZER;
#ifdef DEBUG
bool RuntimeProfiler::has_been_globally_set_up_ = false;
#endif
bool RuntimeProfiler::enabled_ = false;
RuntimeProfiler::RuntimeProfiler(Isolate* isolate)
: isolate_(isolate),
sampler_threshold_(kSamplerThresholdInit),
sampler_threshold_size_factor_(kSamplerThresholdSizeFactorInit),
sampler_ticks_until_threshold_adjustment_(
kSamplerTicksBetweenThresholdAdjustment),
sampler_window_position_(0),
any_ic_changed_(false),
code_generated_(false) {
ClearSampleBuffer();
}
void RuntimeProfiler::GlobalSetUp() {
ASSERT(!has_been_globally_set_up_);
enabled_ = V8::UseCrankshaft() && FLAG_opt;
#ifdef DEBUG
has_been_globally_set_up_ = true;
#endif
}
static void GetICCounts(JSFunction* function,
int* ic_with_type_info_count,
int* ic_total_count,
int* percentage) {
*ic_total_count = 0;
*ic_with_type_info_count = 0;
Object* raw_info =
function->shared()->code()->type_feedback_info();
if (raw_info->IsTypeFeedbackInfo()) {
TypeFeedbackInfo* info = TypeFeedbackInfo::cast(raw_info);
*ic_with_type_info_count = info->ic_with_type_info_count();
*ic_total_count = info->ic_total_count();
}
*percentage = *ic_total_count > 0
? 100 * *ic_with_type_info_count / *ic_total_count
: 100;
}
void RuntimeProfiler::Optimize(JSFunction* function, const char* reason) {
ASSERT(function->IsOptimizable());
if (FLAG_trace_opt) {
PrintF("[marking ");
function->PrintName();
PrintF(" 0x%" V8PRIxPTR, reinterpret_cast<intptr_t>(function->address()));
PrintF(" for recompilation, reason: %s", reason);
if (FLAG_type_info_threshold > 0) {
int typeinfo, total, percentage;
GetICCounts(function, &typeinfo, &total, &percentage);
PrintF(", ICs with typeinfo: %d/%d (%d%%)", typeinfo, total, percentage);
}
PrintF("]\n");
}
// The next call to the function will trigger optimization.
function->MarkForLazyRecompilation();
}
void RuntimeProfiler::AttemptOnStackReplacement(JSFunction* function) {
// See AlwaysFullCompiler (in compiler.cc) comment on why we need
// Debug::has_break_points().
ASSERT(function->IsMarkedForLazyRecompilation());
if (!FLAG_use_osr ||
isolate_->DebuggerHasBreakPoints() ||
function->IsBuiltin()) {
return;
}
SharedFunctionInfo* shared = function->shared();
// If the code is not optimizable, don't try OSR.
if (!shared->code()->optimizable()) return;
// We are not prepared to do OSR for a function that already has an
// allocated arguments object. The optimized code would bypass it for
// arguments accesses, which is unsound. Don't try OSR.
if (shared->uses_arguments()) return;
// We're using on-stack replacement: patch the unoptimized code so that
// any back edge in any unoptimized frame will trigger on-stack
// replacement for that frame.
if (FLAG_trace_osr) {
PrintF("[patching stack checks in ");
function->PrintName();
PrintF(" for on-stack replacement]\n");
}
// Get the stack check stub code object to match against. We aren't
// prepared to generate it, but we don't expect to have to.
bool found_code = false;
Code* stack_check_code = NULL;
if (FLAG_count_based_interrupts) {
InterruptStub interrupt_stub;
found_code = interrupt_stub.FindCodeInCache(&stack_check_code);
} else // NOLINT
{ // NOLINT
StackCheckStub check_stub;
found_code = check_stub.FindCodeInCache(&stack_check_code);
}
if (found_code) {
Code* replacement_code =
isolate_->builtins()->builtin(Builtins::kOnStackReplacement);
Code* unoptimized_code = shared->code();
Deoptimizer::PatchStackCheckCode(unoptimized_code,
stack_check_code,
replacement_code);
}
}
void RuntimeProfiler::ClearSampleBuffer() {
memset(sampler_window_, 0, sizeof(sampler_window_));
memset(sampler_window_weight_, 0, sizeof(sampler_window_weight_));
}
int RuntimeProfiler::LookupSample(JSFunction* function) {
int weight = 0;
for (int i = 0; i < kSamplerWindowSize; i++) {
Object* sample = sampler_window_[i];
if (sample != NULL) {
bool fits = FLAG_lookup_sample_by_shared
? (function->shared() == JSFunction::cast(sample)->shared())
: (function == JSFunction::cast(sample));
if (fits) {
weight += sampler_window_weight_[i];
}
}
}
return weight;
}
void RuntimeProfiler::AddSample(JSFunction* function, int weight) {
ASSERT(IsPowerOf2(kSamplerWindowSize));
sampler_window_[sampler_window_position_] = function;
sampler_window_weight_[sampler_window_position_] = weight;
sampler_window_position_ = (sampler_window_position_ + 1) &
(kSamplerWindowSize - 1);
}
void RuntimeProfiler::OptimizeNow() {
HandleScope scope(isolate_);
// Run through the JavaScript frames and collect them. If we already
// have a sample of the function, we mark it for optimizations
// (eagerly or lazily).
JSFunction* samples[kSamplerFrameCount];
int sample_count = 0;
int frame_count = 0;
int frame_count_limit = FLAG_watch_ic_patching ? FLAG_frame_count
: kSamplerFrameCount;
for (JavaScriptFrameIterator it(isolate_);
frame_count++ < frame_count_limit && !it.done();
it.Advance()) {
JavaScriptFrame* frame = it.frame();
JSFunction* function = JSFunction::cast(frame->function());
if (!FLAG_watch_ic_patching) {
// Adjust threshold each time we have processed
// a certain number of ticks.
if (sampler_ticks_until_threshold_adjustment_ > 0) {
sampler_ticks_until_threshold_adjustment_--;
if (sampler_ticks_until_threshold_adjustment_ <= 0) {
// If the threshold is not already at the minimum
// modify and reset the ticks until next adjustment.
if (sampler_threshold_ > kSamplerThresholdMin) {
sampler_threshold_ -= kSamplerThresholdDelta;
sampler_ticks_until_threshold_adjustment_ =
kSamplerTicksBetweenThresholdAdjustment;
}
}
}
}
SharedFunctionInfo* shared = function->shared();
Code* shared_code = shared->code();
if (shared_code->kind() != Code::FUNCTION) continue;
if (function->IsMarkedForLazyRecompilation()) {
int nesting = shared_code->allow_osr_at_loop_nesting_level();
if (nesting == 0) AttemptOnStackReplacement(function);
int new_nesting = Min(nesting + 1, Code::kMaxLoopNestingMarker);
shared_code->set_allow_osr_at_loop_nesting_level(new_nesting);
}
// Only record top-level code on top of the execution stack and
// avoid optimizing excessively large scripts since top-level code
// will be executed only once.
const int kMaxToplevelSourceSize = 10 * 1024;
if (shared->is_toplevel() &&
(frame_count > 1 || shared->SourceSize() > kMaxToplevelSourceSize)) {
continue;
}
// Do not record non-optimizable functions.
if (shared->optimization_disabled()) {
if (shared->deopt_count() >= Compiler::kDefaultMaxOptCount) {
// If optimization was disabled due to many deoptimizations,
// then check if the function is hot and try to reenable optimization.
int ticks = shared_code->profiler_ticks();
if (ticks >= kProfilerTicksBeforeReenablingOptimization) {
shared_code->set_profiler_ticks(0);
shared->TryReenableOptimization();
} else {
shared_code->set_profiler_ticks(ticks + 1);
}
}
continue;
}
if (!function->IsOptimizable()) continue;
if (FLAG_watch_ic_patching) {
int ticks = shared_code->profiler_ticks();
if (ticks >= kProfilerTicksBeforeOptimization) {
int typeinfo, total, percentage;
GetICCounts(function, &typeinfo, &total, &percentage);
if (percentage >= FLAG_type_info_threshold) {
// If this particular function hasn't had any ICs patched for enough
// ticks, optimize it now.
Optimize(function, "hot and stable");
} else if (ticks >= kTicksWhenNotEnoughTypeInfo) {
Optimize(function, "not much type info but very hot");
} else {
shared_code->set_profiler_ticks(ticks + 1);
if (FLAG_trace_opt_verbose) {
PrintF("[not yet optimizing ");
function->PrintName();
PrintF(", not enough type info: %d/%d (%d%%)]\n",
typeinfo, total, percentage);
}
}
} else if (!any_ic_changed_ &&
shared_code->instruction_size() < kMaxSizeEarlyOpt) {
// If no IC was patched since the last tick and this function is very
// small, optimistically optimize it now.
Optimize(function, "small function");
} else {
shared_code->set_profiler_ticks(ticks + 1);
}
} else { // !FLAG_watch_ic_patching
samples[sample_count++] = function;
int function_size = function->shared()->SourceSize();
int threshold_size_factor = (function_size > kSizeLimit)
? sampler_threshold_size_factor_
: 1;
int threshold = sampler_threshold_ * threshold_size_factor;
if (LookupSample(function) >= threshold) {
Optimize(function, "sampler window lookup");
}
}
}
if (FLAG_watch_ic_patching) {
any_ic_changed_ = false;
} else { // !FLAG_watch_ic_patching
// Add the collected functions as samples. It's important not to do
// this as part of collecting them because this will interfere with
// the sample lookup in case of recursive functions.
for (int i = 0; i < sample_count; i++) {
AddSample(samples[i], kSamplerFrameWeight[i]);
}
}
}
void RuntimeProfiler::NotifyTick() {
if (FLAG_count_based_interrupts) return;
isolate_->stack_guard()->RequestRuntimeProfilerTick();
}
void RuntimeProfiler::SetUp() {
ASSERT(has_been_globally_set_up_);
if (!FLAG_watch_ic_patching) {
ClearSampleBuffer();
}
// If the ticker hasn't already started, make sure to do so to get
// the ticks for the runtime profiler.
if (IsEnabled()) isolate_->logger()->EnsureTickerStarted();
}
void RuntimeProfiler::Reset() {
if (!FLAG_watch_ic_patching) {
sampler_threshold_ = kSamplerThresholdInit;
sampler_threshold_size_factor_ = kSamplerThresholdSizeFactorInit;
sampler_ticks_until_threshold_adjustment_ =
kSamplerTicksBetweenThresholdAdjustment;
}
}
void RuntimeProfiler::TearDown() {
// Nothing to do.
}
int RuntimeProfiler::SamplerWindowSize() {
return kSamplerWindowSize;
}
// Update the pointers in the sampler window after a GC.
void RuntimeProfiler::UpdateSamplesAfterScavenge() {
for (int i = 0; i < kSamplerWindowSize; i++) {
Object* function = sampler_window_[i];
if (function != NULL && isolate_->heap()->InNewSpace(function)) {
MapWord map_word = HeapObject::cast(function)->map_word();
if (map_word.IsForwardingAddress()) {
sampler_window_[i] = map_word.ToForwardingAddress();
} else {
sampler_window_[i] = NULL;
}
}
}
}
void RuntimeProfiler::HandleWakeUp(Isolate* isolate) {
// The profiler thread must still be waiting.
ASSERT(NoBarrier_Load(&state_) >= 0);
// In IsolateEnteredJS we have already incremented the counter and
// undid the decrement done by the profiler thread. Increment again
// to get the right count of active isolates.
NoBarrier_AtomicIncrement(&state_, 1);
semaphore.Pointer()->Signal();
}
bool RuntimeProfiler::IsSomeIsolateInJS() {
return NoBarrier_Load(&state_) > 0;
}
bool RuntimeProfiler::WaitForSomeIsolateToEnterJS() {
Atomic32 old_state = NoBarrier_CompareAndSwap(&state_, 0, -1);
ASSERT(old_state >= -1);
if (old_state != 0) return false;
semaphore.Pointer()->Wait();
return true;
}
void RuntimeProfiler::StopRuntimeProfilerThreadBeforeShutdown(Thread* thread) {
// Do a fake increment. If the profiler is waiting on the semaphore,
// the returned state is 0, which can be left as an initial state in
// case profiling is restarted later. If the profiler is not
// waiting, the increment will prevent it from waiting, but has to
// be undone after the profiler is stopped.
Atomic32 new_state = NoBarrier_AtomicIncrement(&state_, 1);
ASSERT(new_state >= 0);
if (new_state == 0) {
// The profiler thread is waiting. Wake it up. It must check for
// stop conditions before attempting to wait again.
semaphore.Pointer()->Signal();
}
thread->Join();
// The profiler thread is now stopped. Undo the increment in case it
// was not waiting.
if (new_state != 0) {
NoBarrier_AtomicIncrement(&state_, -1);
}
}
void RuntimeProfiler::RemoveDeadSamples() {
for (int i = 0; i < kSamplerWindowSize; i++) {
Object* function = sampler_window_[i];
if (function != NULL &&
!Marking::MarkBitFrom(HeapObject::cast(function)).Get()) {
sampler_window_[i] = NULL;
}
}
}
void RuntimeProfiler::UpdateSamplesAfterCompact(ObjectVisitor* visitor) {
for (int i = 0; i < kSamplerWindowSize; i++) {
visitor->VisitPointer(&sampler_window_[i]);
}
}
bool RuntimeProfilerRateLimiter::SuspendIfNecessary() {
if (!RuntimeProfiler::IsSomeIsolateInJS()) {
return RuntimeProfiler::WaitForSomeIsolateToEnterJS();
}
return false;
}
} } // namespace v8::internal