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| //===-- TimeProfiler.cpp - Hierarchical Time Profiler ---------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements hierarchical time profiler.
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/TimeProfiler.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/JSON.h"
#include <cassert>
#include <chrono>
#include <string>
#include <vector>
using namespace std::chrono;
namespace llvm {
TimeTraceProfiler *TimeTraceProfilerInstance = nullptr;
typedef duration<steady_clock::rep, steady_clock::period> DurationType;
typedef time_point<steady_clock> TimePointType;
typedef std::pair<size_t, DurationType> CountAndDurationType;
typedef std::pair<std::string, CountAndDurationType>
NameAndCountAndDurationType;
struct Entry {
TimePointType Start;
TimePointType End;
std::string Name;
std::string Detail;
Entry(TimePointType &&S, TimePointType &&E, std::string &&N, std::string &&Dt)
: Start(std::move(S)), End(std::move(E)), Name(std::move(N)),
Detail(std::move(Dt)){};
// Calculate timings for FlameGraph. Cast time points to microsecond precision
// rather than casting duration. This avoid truncation issues causing inner
// scopes overruning outer scopes.
steady_clock::rep getFlameGraphStartUs(TimePointType StartTime) const {
return (time_point_cast<microseconds>(Start) -
time_point_cast<microseconds>(StartTime))
.count();
}
steady_clock::rep getFlameGraphDurUs() const {
return (time_point_cast<microseconds>(End) -
time_point_cast<microseconds>(Start))
.count();
}
};
struct TimeTraceProfiler {
TimeTraceProfiler() {
StartTime = steady_clock::now();
}
void begin(std::string Name, llvm::function_ref<std::string()> Detail) {
Stack.emplace_back(steady_clock::now(), TimePointType(), std::move(Name),
Detail());
}
void end() {
assert(!Stack.empty() && "Must call begin() first");
auto &E = Stack.back();
E.End = steady_clock::now();
// Check that end times monotonically increase.
assert((Entries.empty() ||
(E.getFlameGraphStartUs(StartTime) + E.getFlameGraphDurUs() >=
Entries.back().getFlameGraphStartUs(StartTime) +
Entries.back().getFlameGraphDurUs())) &&
"TimeProfiler scope ended earlier than previous scope");
// Calculate duration at full precision for overall counts.
DurationType Duration = E.End - E.Start;
// Only include sections longer or equal to TimeTraceGranularity msec.
if (duration_cast<microseconds>(Duration).count() >= TimeTraceGranularity)
Entries.emplace_back(E);
// Track total time taken by each "name", but only the topmost levels of
// them; e.g. if there's a template instantiation that instantiates other
// templates from within, we only want to add the topmost one. "topmost"
// happens to be the ones that don't have any currently open entries above
// itself.
if (std::find_if(++Stack.rbegin(), Stack.rend(), [&](const Entry &Val) {
return Val.Name == E.Name;
}) == Stack.rend()) {
auto &CountAndTotal = CountAndTotalPerName[E.Name];
CountAndTotal.first++;
CountAndTotal.second += Duration;
}
Stack.pop_back();
}
void Write(raw_pwrite_stream &OS) {
assert(Stack.empty() &&
"All profiler sections should be ended when calling Write");
json::OStream J(OS);
J.objectBegin();
J.attributeBegin("traceEvents");
J.arrayBegin();
// Emit all events for the main flame graph.
for (const auto &E : Entries) {
auto StartUs = E.getFlameGraphStartUs(StartTime);
auto DurUs = E.getFlameGraphDurUs();
J.object([&]{
J.attribute("pid", 1);
J.attribute("tid", 0);
J.attribute("ph", "X");
J.attribute("ts", StartUs);
J.attribute("dur", DurUs);
J.attribute("name", E.Name);
J.attributeObject("args", [&] { J.attribute("detail", E.Detail); });
});
}
// Emit totals by section name as additional "thread" events, sorted from
// longest one.
int Tid = 1;
std::vector<NameAndCountAndDurationType> SortedTotals;
SortedTotals.reserve(CountAndTotalPerName.size());
for (const auto &E : CountAndTotalPerName)
SortedTotals.emplace_back(E.getKey(), E.getValue());
llvm::sort(SortedTotals.begin(), SortedTotals.end(),
[](const NameAndCountAndDurationType &A,
const NameAndCountAndDurationType &B) {
return A.second.second > B.second.second;
});
for (const auto &E : SortedTotals) {
auto DurUs = duration_cast<microseconds>(E.second.second).count();
auto Count = CountAndTotalPerName[E.first].first;
J.object([&]{
J.attribute("pid", 1);
J.attribute("tid", Tid);
J.attribute("ph", "X");
J.attribute("ts", 0);
J.attribute("dur", DurUs);
J.attribute("name", "Total " + E.first);
J.attributeObject("args", [&] {
J.attribute("count", int64_t(Count));
J.attribute("avg ms", int64_t(DurUs / Count / 1000));
});
});
++Tid;
}
// Emit metadata event with process name.
J.object([&] {
J.attribute("cat", "");
J.attribute("pid", 1);
J.attribute("tid", 0);
J.attribute("ts", 0);
J.attribute("ph", "M");
J.attribute("name", "process_name");
J.attributeObject("args", [&] { J.attribute("name", "clang"); });
});
J.arrayEnd();
J.attributeEnd();
J.objectEnd();
}
SmallVector<Entry, 16> Stack;
SmallVector<Entry, 128> Entries;
StringMap<CountAndDurationType> CountAndTotalPerName;
TimePointType StartTime;
// Minimum time granularity (in microseconds)
unsigned TimeTraceGranularity;
};
void timeTraceProfilerInitialize(unsigned TimeTraceGranularity) {
assert(TimeTraceProfilerInstance == nullptr &&
"Profiler should not be initialized");
TimeTraceProfilerInstance = new TimeTraceProfiler();
TimeTraceProfilerInstance->TimeTraceGranularity = TimeTraceGranularity;
}
void timeTraceProfilerCleanup() {
delete TimeTraceProfilerInstance;
TimeTraceProfilerInstance = nullptr;
}
void timeTraceProfilerWrite(raw_pwrite_stream &OS) {
assert(TimeTraceProfilerInstance != nullptr &&
"Profiler object can't be null");
TimeTraceProfilerInstance->Write(OS);
}
void timeTraceProfilerBegin(StringRef Name, StringRef Detail) {
if (TimeTraceProfilerInstance != nullptr)
TimeTraceProfilerInstance->begin(Name, [&]() { return Detail; });
}
void timeTraceProfilerBegin(StringRef Name,
llvm::function_ref<std::string()> Detail) {
if (TimeTraceProfilerInstance != nullptr)
TimeTraceProfilerInstance->begin(Name, Detail);
}
void timeTraceProfilerEnd() {
if (TimeTraceProfilerInstance != nullptr)
TimeTraceProfilerInstance->end();
}
} // namespace llvm
|