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// Copyright 2010 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 "mark-compact.h"
#include "platform.h"
#include "scopeinfo.h"
namespace v8 {
namespace internal {
class PendingListNode : public Malloced {
public:
explicit PendingListNode(JSFunction* function);
~PendingListNode() { Destroy(); }
PendingListNode* next() const { return next_; }
void set_next(PendingListNode* node) { next_ = node; }
Handle<JSFunction> function() { return Handle<JSFunction>::cast(function_); }
// If the function is garbage collected before we've had the chance
// to optimize it the weak handle will be null.
bool IsValid() { return !function_.is_null(); }
// Returns the number of microseconds this node has been pending.
int Delay() const { return static_cast<int>(OS::Ticks() - start_); }
private:
void Destroy();
static void WeakCallback(v8::Persistent<v8::Value> object, void* data);
PendingListNode* next_;
Handle<Object> function_; // Weak handle.
int64_t start_;
};
// Optimization sampler constants.
static const int kSamplerFrameCount = 2;
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 kSamplerThresholdSizeFactorMin = 1;
static const int kSamplerThresholdSizeFactorDelta = 1;
static const int kSizeLimit = 1500;
PendingListNode::PendingListNode(JSFunction* function) : next_(NULL) {
GlobalHandles* global_handles = Isolate::Current()->global_handles();
function_ = global_handles->Create(function);
start_ = OS::Ticks();
global_handles->MakeWeak(function_.location(), this, &WeakCallback);
}
void PendingListNode::Destroy() {
if (!IsValid()) return;
GlobalHandles* global_handles = Isolate::Current()->global_handles();
global_handles->Destroy(function_.location());
function_= Handle<Object>::null();
}
void PendingListNode::WeakCallback(v8::Persistent<v8::Value>, void* data) {
reinterpret_cast<PendingListNode*>(data)->Destroy();
}
Atomic32 RuntimeProfiler::state_ = 0;
// TODO(isolates): Create the semaphore lazily and clean it up when no
// longer required.
#ifdef ENABLE_LOGGING_AND_PROFILING
Semaphore* RuntimeProfiler::semaphore_ = OS::CreateSemaphore(0);
#endif
#ifdef DEBUG
bool RuntimeProfiler::has_been_globally_setup_ = 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),
js_ratio_(0),
sampler_window_position_(0),
optimize_soon_list_(NULL),
state_window_position_(0),
state_window_ticks_(0) {
state_counts_[IN_NON_JS_STATE] = kStateWindowSize;
state_counts_[IN_JS_STATE] = 0;
STATIC_ASSERT(IN_NON_JS_STATE == 0);
memset(state_window_, 0, sizeof(state_window_));
ClearSampleBuffer();
}
void RuntimeProfiler::GlobalSetup() {
ASSERT(!has_been_globally_setup_);
enabled_ = V8::UseCrankshaft() && FLAG_opt;
#ifdef DEBUG
has_been_globally_setup_ = true;
#endif
}
void RuntimeProfiler::Optimize(JSFunction* function, bool eager, int delay) {
ASSERT(function->IsOptimizable());
if (FLAG_trace_opt) {
PrintF("[marking (%s) ", eager ? "eagerly" : "lazily");
function->PrintName();
PrintF(" for recompilation");
if (delay > 0) {
PrintF(" (delayed %0.3f ms)", static_cast<double>(delay) / 1000);
}
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_->debug()->has_break_points() ||
function->IsBuiltin()) {
return;
}
SharedFunctionInfo* shared = function->shared();
// If the code is not optimizable or references context slots, don't try OSR.
if (!shared->code()->optimizable() || !shared->allows_lazy_compilation()) {
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->scope_info()->HasArgumentsShadow()) 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.
StackCheckStub check_stub;
Object* check_code;
MaybeObject* maybe_check_code = check_stub.TryGetCode();
if (maybe_check_code->ToObject(&check_code)) {
Code* replacement_code =
isolate_->builtins()->builtin(Builtins::kOnStackReplacement);
Code* unoptimized_code = shared->code();
Deoptimizer::PatchStackCheckCode(unoptimized_code,
Code::cast(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) {
if (function == sample) {
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_);
PendingListNode* current = optimize_soon_list_;
while (current != NULL) {
PendingListNode* next = current->next();
if (current->IsValid()) {
Handle<JSFunction> function = current->function();
int delay = current->Delay();
if (function->IsOptimizable()) {
Optimize(*function, true, delay);
}
}
delete current;
current = next;
}
optimize_soon_list_ = NULL;
// 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;
for (JavaScriptFrameIterator it(isolate_);
frame_count++ < kSamplerFrameCount && !it.done();
it.Advance()) {
JavaScriptFrame* frame = it.frame();
JSFunction* function = JSFunction::cast(frame->function());
// 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;
}
}
}
if (function->IsMarkedForLazyRecompilation()) {
Code* unoptimized = function->shared()->code();
int nesting = unoptimized->allow_osr_at_loop_nesting_level();
if (nesting == 0) AttemptOnStackReplacement(function);
int new_nesting = Min(nesting + 1, Code::kMaxLoopNestingMarker);
unoptimized->set_allow_osr_at_loop_nesting_level(new_nesting);
}
// Do not record non-optimizable functions.
if (!function->IsOptimizable()) continue;
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;
int current_js_ratio = NoBarrier_Load(&js_ratio_);
// Adjust threshold depending on the ratio of time spent
// in JS code.
if (current_js_ratio < 20) {
// If we spend less than 20% of the time in JS code,
// do not optimize.
continue;
} else if (current_js_ratio < 75) {
// Below 75% of time spent in JS code, only optimize very
// frequently used functions.
threshold *= 3;
}
if (LookupSample(function) >= threshold) {
Optimize(function, false, 0);
isolate_->compilation_cache()->MarkForEagerOptimizing(
Handle<JSFunction>(function));
}
}
// 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::OptimizeSoon(JSFunction* function) {
if (!function->IsOptimizable()) return;
PendingListNode* node = new PendingListNode(function);
node->set_next(optimize_soon_list_);
optimize_soon_list_ = node;
}
#ifdef ENABLE_LOGGING_AND_PROFILING
void RuntimeProfiler::UpdateStateRatio(SamplerState current_state) {
SamplerState old_state = state_window_[state_window_position_];
state_counts_[old_state]--;
state_window_[state_window_position_] = current_state;
state_counts_[current_state]++;
ASSERT(IsPowerOf2(kStateWindowSize));
state_window_position_ = (state_window_position_ + 1) &
(kStateWindowSize - 1);
// Note: to calculate correct ratio we have to track how many valid
// ticks are actually in the state window, because on profiler
// startup this number can be less than the window size.
state_window_ticks_ = Min(kStateWindowSize, state_window_ticks_ + 1);
NoBarrier_Store(&js_ratio_, state_counts_[IN_JS_STATE] * 100 /
state_window_ticks_);
}
#endif
void RuntimeProfiler::NotifyTick() {
#ifdef ENABLE_LOGGING_AND_PROFILING
// Record state sample.
SamplerState state = IsSomeIsolateInJS()
? IN_JS_STATE
: IN_NON_JS_STATE;
UpdateStateRatio(state);
isolate_->stack_guard()->RequestRuntimeProfilerTick();
#endif
}
void RuntimeProfiler::Setup() {
ASSERT(has_been_globally_setup_);
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() {
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) {
#ifdef ENABLE_LOGGING_AND_PROFILING
// 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_->Signal();
isolate->ResetEagerOptimizingData();
#endif
}
bool RuntimeProfiler::IsSomeIsolateInJS() {
return NoBarrier_Load(&state_) > 0;
}
bool RuntimeProfiler::WaitForSomeIsolateToEnterJS() {
#ifdef ENABLE_LOGGING_AND_PROFILING
Atomic32 old_state = NoBarrier_CompareAndSwap(&state_, 0, -1);
ASSERT(old_state >= -1);
if (old_state != 0) return false;
semaphore_->Wait();
#endif
return true;
}
void RuntimeProfiler::WakeUpRuntimeProfilerThreadBeforeShutdown() {
#ifdef ENABLE_LOGGING_AND_PROFILING
semaphore_->Signal();
#endif
}
void RuntimeProfiler::RemoveDeadSamples() {
for (int i = 0; i < kSamplerWindowSize; i++) {
Object* function = sampler_window_[i];
if (function != NULL && !HeapObject::cast(function)->IsMarked()) {
sampler_window_[i] = NULL;
}
}
}
void RuntimeProfiler::UpdateSamplesAfterCompact(ObjectVisitor* visitor) {
for (int i = 0; i < kSamplerWindowSize; i++) {
visitor->VisitPointer(&sampler_window_[i]);
}
}
bool RuntimeProfilerRateLimiter::SuspendIfNecessary() {
#ifdef ENABLE_LOGGING_AND_PROFILING
static const int kNonJSTicksThreshold = 100;
if (RuntimeProfiler::IsSomeIsolateInJS()) {
non_js_ticks_ = 0;
} else {
if (non_js_ticks_ < kNonJSTicksThreshold) {
++non_js_ticks_;
} else {
return RuntimeProfiler::WaitForSomeIsolateToEnterJS();
}
}
#endif
return false;
}
} } // namespace v8::internal