Revision: 15944
Author: [email protected]
Date: Tue Jul 30 00:01:16 2013
Log: Simplify sampling rate calculation
Sampling rate is now calculated as total number of samples divided by
profiling time in ms. Before the patch the sampling rate was updated once
per 100ms which doesn't have any obvious advantage over the simpler method.
Also we are going to get rid of the profile node self and total time
calculation in the v8 CPU profiler and only expose profiling start/end time
for CpuProfile and number of ticks on each ProfileNode and let clients do
all the math should they need it.
BUG=None
[email protected], [email protected]
Review URL: https://codereview.chromium.org/21105003
http://code.google.com/p/v8/source/detail?r=15944
Modified:
/branches/bleeding_edge/src/cpu-profiler-inl.h
/branches/bleeding_edge/src/cpu-profiler.cc
/branches/bleeding_edge/src/profile-generator.cc
/branches/bleeding_edge/src/profile-generator.h
/branches/bleeding_edge/test/cctest/test-cpu-profiler.cc
/branches/bleeding_edge/test/cctest/test-profile-generator.cc
=======================================
--- /branches/bleeding_edge/src/cpu-profiler-inl.h Sun Jul 7 04:42:30 2013
+++ /branches/bleeding_edge/src/cpu-profiler-inl.h Tue Jul 30 00:01:16 2013
@@ -68,7 +68,6 @@
TickSample* ProfilerEventsProcessor::TickSampleEvent() {
- generator_->Tick();
TickSampleEventRecord* evt =
new(ticks_buffer_.Enqueue())
TickSampleEventRecord(last_code_event_id_);
return &evt->sample;
=======================================
--- /branches/bleeding_edge/src/cpu-profiler.cc Tue Jul 23 01:12:15 2013
+++ /branches/bleeding_edge/src/cpu-profiler.cc Tue Jul 30 00:01:16 2013
@@ -452,9 +452,8 @@
CpuProfile* CpuProfiler::StopProfiling(const char* title) {
if (!is_profiling_) return NULL;
- const double actual_sampling_rate = generator_->actual_sampling_rate();
StopProcessorIfLastProfile(title);
- CpuProfile* result = profiles_->StopProfiling(title,
actual_sampling_rate);
+ CpuProfile* result = profiles_->StopProfiling(title);
if (result != NULL) {
result->Print();
}
@@ -464,10 +463,9 @@
CpuProfile* CpuProfiler::StopProfiling(String* title) {
if (!is_profiling_) return NULL;
- const double actual_sampling_rate = generator_->actual_sampling_rate();
const char* profile_title = profiles_->GetName(title);
StopProcessorIfLastProfile(profile_title);
- return profiles_->StopProfiling(profile_title, actual_sampling_rate);
+ return profiles_->StopProfiling(profile_title);
}
=======================================
--- /branches/bleeding_edge/src/profile-generator.cc Tue Jul 23 08:01:38
2013
+++ /branches/bleeding_edge/src/profile-generator.cc Tue Jul 30 00:01:16
2013
@@ -370,6 +370,15 @@
root_->total_ticks(), root_->self_ticks(),
root_->GetTotalMillis(), root_->GetSelfMillis());
}
+
+
+CpuProfile::CpuProfile(const char* title, unsigned uid, bool
record_samples)
+ : title_(title),
+ uid_(uid),
+ record_samples_(record_samples),
+ start_time_ms_(OS::TimeCurrentMillis()),
+ end_time_ms_(0) {
+}
void CpuProfile::AddPath(const Vector<CodeEntry*>& path) {
@@ -378,13 +387,15 @@
}
-void CpuProfile::CalculateTotalTicks() {
+void CpuProfile::CalculateTotalTicksAndSamplingRate() {
+ end_time_ms_ = OS::TimeCurrentMillis();
top_down_.CalculateTotalTicks();
-}
-
-void CpuProfile::SetActualSamplingRate(double actual_sampling_rate) {
- top_down_.SetTickRatePerMs(actual_sampling_rate);
+ double duration = end_time_ms_ - start_time_ms_;
+ if (duration < 1) duration = 1;
+ unsigned ticks = top_down_.root()->total_ticks();
+ double rate = ticks / duration;
+ top_down_.SetTickRatePerMs(rate);
}
@@ -529,8 +540,7 @@
}
-CpuProfile* CpuProfilesCollection::StopProfiling(const char* title,
- double
actual_sampling_rate) {
+CpuProfile* CpuProfilesCollection::StopProfiling(const char* title) {
const int title_len = StrLength(title);
CpuProfile* profile = NULL;
current_profiles_semaphore_->Wait();
@@ -543,8 +553,7 @@
current_profiles_semaphore_->Signal();
if (profile == NULL) return NULL;
- profile->CalculateTotalTicks();
- profile->SetActualSamplingRate(actual_sampling_rate);
+ profile->CalculateTotalTicksAndSamplingRate();
finished_profiles_.Add(profile);
return profile;
}
@@ -599,29 +608,6 @@
code_entries_.Add(code_entry);
return code_entry;
}
-
-
-void SampleRateCalculator::Tick() {
- if (--wall_time_query_countdown_ == 0)
- UpdateMeasurements(OS::TimeCurrentMillis());
-}
-
-
-void SampleRateCalculator::UpdateMeasurements(double current_time) {
- if (measurements_count_++ != 0) {
- const double measured_ticks_per_ms =
- (kWallTimeQueryIntervalMs * ticks_per_ms_) /
- (current_time - last_wall_time_);
- // Update the average value.
- ticks_per_ms_ +=
- (measured_ticks_per_ms - ticks_per_ms_) / measurements_count_;
- // Update the externally accessible result.
- result_ = static_cast<AtomicWord>(ticks_per_ms_ * kResultScale);
- }
- last_wall_time_ = current_time;
- wall_time_query_countdown_ =
- static_cast<unsigned>(kWallTimeQueryIntervalMs * ticks_per_ms_);
-}
const char* const ProfileGenerator::kAnonymousFunctionName =
=======================================
--- /branches/bleeding_edge/src/profile-generator.h Sat Jul 6 02:12:09 2013
+++ /branches/bleeding_edge/src/profile-generator.h Tue Jul 30 00:01:16 2013
@@ -203,13 +203,11 @@
class CpuProfile {
public:
- CpuProfile(const char* title, unsigned uid, bool record_samples)
- : title_(title), uid_(uid), record_samples_(record_samples) { }
+ CpuProfile(const char* title, unsigned uid, bool record_samples);
// Add pc -> ... -> main() call path to the profile.
void AddPath(const Vector<CodeEntry*>& path);
- void CalculateTotalTicks();
- void SetActualSamplingRate(double actual_sampling_rate);
+ void CalculateTotalTicksAndSamplingRate();
INLINE(const char* title() const) { return title_; }
INLINE(unsigned uid() const) { return uid_; }
@@ -227,6 +225,8 @@
const char* title_;
unsigned uid_;
bool record_samples_;
+ double start_time_ms_;
+ double end_time_ms_;
List<ProfileNode*> samples_;
ProfileTree top_down_;
@@ -286,7 +286,7 @@
~CpuProfilesCollection();
bool StartProfiling(const char* title, unsigned uid, bool
record_samples);
- CpuProfile* StopProfiling(const char* title, double
actual_sampling_rate);
+ CpuProfile* StopProfiling(const char* title);
List<CpuProfile*>* profiles() { return &finished_profiles_; }
const char* GetName(Name* name) {
return function_and_resource_names_.GetName(name);
@@ -329,44 +329,6 @@
};
-class SampleRateCalculator {
- public:
- SampleRateCalculator()
- : result_(Logger::kSamplingIntervalMs * kResultScale),
- ticks_per_ms_(Logger::kSamplingIntervalMs),
- measurements_count_(0),
- wall_time_query_countdown_(1) {
- }
-
- double ticks_per_ms() {
- return result_ / static_cast<double>(kResultScale);
- }
- void Tick();
- void UpdateMeasurements(double current_time);
-
- // Instead of querying current wall time each tick,
- // we use this constant to control query intervals.
- static const unsigned kWallTimeQueryIntervalMs = 100;
-
- private:
- // As the result needs to be accessed from a different thread, we
- // use type that guarantees atomic writes to memory. There should
- // be <= 1000 ticks per second, thus storing a value of a 10 ** 5
- // order should provide enough precision while keeping away from a
- // potential overflow.
- static const int kResultScale = 100000;
-
- AtomicWord result_;
- // All other fields are accessed only from the sampler thread.
- double ticks_per_ms_;
- unsigned measurements_count_;
- unsigned wall_time_query_countdown_;
- double last_wall_time_;
-
- DISALLOW_COPY_AND_ASSIGN(SampleRateCalculator);
-};
-
-
class ProfileGenerator {
public:
explicit ProfileGenerator(CpuProfilesCollection* profiles);
@@ -374,11 +336,6 @@
void RecordTickSample(const TickSample& sample);
INLINE(CodeMap* code_map()) { return &code_map_; }
-
- INLINE(void Tick()) { sample_rate_calc_.Tick(); }
- INLINE(double actual_sampling_rate()) {
- return sample_rate_calc_.ticks_per_ms();
- }
static const char* const kAnonymousFunctionName;
static const char* const kProgramEntryName;
@@ -395,7 +352,6 @@
CodeEntry* program_entry_;
CodeEntry* gc_entry_;
CodeEntry* unresolved_entry_;
- SampleRateCalculator sample_rate_calc_;
DISALLOW_COPY_AND_ASSIGN(ProfileGenerator);
};
=======================================
--- /branches/bleeding_edge/test/cctest/test-cpu-profiler.cc Tue Jul 23
08:01:38 2013
+++ /branches/bleeding_edge/test/cctest/test-cpu-profiler.cc Tue Jul 30
00:01:16 2013
@@ -222,7 +222,7 @@
processor.StopSynchronously();
processor.Join();
- CpuProfile* profile = profiles->StopProfiling("", 1);
+ CpuProfile* profile = profiles->StopProfiling("");
CHECK_NE(NULL, profile);
// Check call trees.
@@ -286,7 +286,7 @@
processor.StopSynchronously();
processor.Join();
- CpuProfile* profile = profiles->StopProfiling("", 1);
+ CpuProfile* profile = profiles->StopProfiling("");
CHECK_NE(NULL, profile);
int actual_depth = 0;
=======================================
--- /branches/bleeding_edge/test/cctest/test-profile-generator.cc Sun Jul
7 04:42:30 2013
+++ /branches/bleeding_edge/test/cctest/test-profile-generator.cc Tue Jul
30 00:01:16 2013
@@ -41,7 +41,6 @@
using i::ProfileNode;
using i::ProfileTree;
using i::ProfileGenerator;
-using i::SampleRateCalculator;
using i::TickSample;
using i::Vector;
@@ -485,7 +484,7 @@
sample3.frames_count = 2;
generator.RecordTickSample(sample3);
- CpuProfile* profile = profiles.StopProfiling("", 1);
+ CpuProfile* profile = profiles.StopProfiling("");
CHECK_NE(NULL, profile);
ProfileTreeTestHelper top_down_test_helper(profile->top_down());
CHECK_EQ(NULL, top_down_test_helper.Walk(entry2));
@@ -503,56 +502,6 @@
CHECK_NE(NULL, node4);
CHECK_EQ(entry1, node4->entry());
}
-
-
-TEST(SampleRateCalculator) {
- const double kSamplingIntervalMs = i::Logger::kSamplingIntervalMs;
-
- // Verify that ticking exactly in query intervals results in the
- // initial sampling interval.
- double time = 0.0;
- SampleRateCalculator calc1;
- CHECK_EQ(kSamplingIntervalMs, calc1.ticks_per_ms());
- calc1.UpdateMeasurements(time);
- CHECK_EQ(kSamplingIntervalMs, calc1.ticks_per_ms());
- time += SampleRateCalculator::kWallTimeQueryIntervalMs;
- calc1.UpdateMeasurements(time);
- CHECK_EQ(kSamplingIntervalMs, calc1.ticks_per_ms());
- time += SampleRateCalculator::kWallTimeQueryIntervalMs;
- calc1.UpdateMeasurements(time);
- CHECK_EQ(kSamplingIntervalMs, calc1.ticks_per_ms());
- time += SampleRateCalculator::kWallTimeQueryIntervalMs;
- calc1.UpdateMeasurements(time);
- CHECK_EQ(kSamplingIntervalMs, calc1.ticks_per_ms());
-
- SampleRateCalculator calc2;
- time = 0.0;
- CHECK_EQ(kSamplingIntervalMs, calc2.ticks_per_ms());
- calc2.UpdateMeasurements(time);
- CHECK_EQ(kSamplingIntervalMs, calc2.ticks_per_ms());
- time += SampleRateCalculator::kWallTimeQueryIntervalMs * 0.5;
- calc2.UpdateMeasurements(time);
- // (1.0 + 2.0) / 2
- CHECK_EQ(kSamplingIntervalMs * 1.5, calc2.ticks_per_ms());
- time += SampleRateCalculator::kWallTimeQueryIntervalMs * 0.75;
- calc2.UpdateMeasurements(time);
- // (1.0 + 2.0 + 2.0) / 3
- CHECK_EQ(kSamplingIntervalMs * 5.0, floor(calc2.ticks_per_ms() * 3.0 +
0.5));
-
- SampleRateCalculator calc3;
- time = 0.0;
- CHECK_EQ(kSamplingIntervalMs, calc3.ticks_per_ms());
- calc3.UpdateMeasurements(time);
- CHECK_EQ(kSamplingIntervalMs, calc3.ticks_per_ms());
- time += SampleRateCalculator::kWallTimeQueryIntervalMs * 2;
- calc3.UpdateMeasurements(time);
- // (1.0 + 0.5) / 2
- CHECK_EQ(kSamplingIntervalMs * 0.75, calc3.ticks_per_ms());
- time += SampleRateCalculator::kWallTimeQueryIntervalMs * 1.5;
- calc3.UpdateMeasurements(time);
- // (1.0 + 0.5 + 0.5) / 3
- CHECK_EQ(kSamplingIntervalMs * 2.0, floor(calc3.ticks_per_ms() * 3.0 +
0.5));
-}
static void CheckNodeIds(ProfileNode* node, int* expectedId) {
@@ -598,7 +547,7 @@
sample3.frames_count = 2;
generator.RecordTickSample(sample3);
- CpuProfile* profile = profiles.StopProfiling("", 1);
+ CpuProfile* profile = profiles.StopProfiling("");
int nodeId = 1;
CheckNodeIds(profile->top_down()->root(), &nodeId);
CHECK_EQ(7, nodeId - 1);
@@ -627,7 +576,7 @@
sample1.frames_count = 1;
generator.RecordTickSample(sample1);
- CpuProfile* profile = profiles.StopProfiling("", 1);
+ CpuProfile* profile = profiles.StopProfiling("");
int nodeId = 1;
CheckNodeIds(profile->top_down()->root(), &nodeId);
CHECK_EQ(3, nodeId - 1);
--
--
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