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/*
* Copyright (c) 2015, Charlie Curtsinger and Emery Berger,
* University of Massachusetts Amherst
* This file is part of the Coz project. See LICENSE.md file at the top-level
* directory of this distribution and at http://github.com/plasma-umass/coz.
*/
#if !defined(CAUSAL_RUNTIME_PROFILER_H)
#define CAUSAL_RUNTIME_PROFILER_H
#include <atomic>
#include <cstdint>
#include <fstream>
#include <string>
#include <unordered_map>
#include <vector>
#include "coz.h"
#include "inspect.h"
#include "progress_point.h"
#include "thread_state.h"
#include "util.h"
#include "ccutil/spinlock.h"
#include "ccutil/static_map.h"
/// Type of a thread entry function
typedef void* (*thread_fn_t)(void*);
/// The type of a main function
typedef int (*main_fn_t)(int, char**, char**);
enum {
SampleSignal = SIGPROF, //< Signal to generate when samples are ready
SamplePeriod = 1000000, //< Time between samples (1ms)
SampleBatchSize = 10, //< Samples to batch together for one processing run
SpeedupDivisions = 20, //< How many different speedups to try (20 = 5% increments)
ZeroSpeedupWeight = 7, //< Weight of speedup=0 versus other speedup values (7 = ~25% of experiments run with zero speedup)
ExperimentMinTime = SamplePeriod * SampleBatchSize * 50, //< Minimum experiment length
ExperimentCoolOffTime = SamplePeriod * SampleBatchSize, //< Time to wait after an experiment
ExperimentTargetDelta = 5 //< Target minimum number of visits to a progress point during an experiment
};
/**
* Argument type passed to wrapped threads
*/
struct thread_start_arg {
thread_fn_t _fn;
void* _arg;
size_t _parent_delay_time;
thread_start_arg(thread_fn_t fn, void* arg, size_t t) :
_fn(fn), _arg(arg), _parent_delay_time(t) {}
};
void init_coz(void);
class profiler {
public:
/// Start the profiler
void startup(const std::string& outfile,
line* fixed_line,
int fixed_speedup,
bool end_to_end);
/// Shut down the profiler
void shutdown();
/// Get or create a progress point to measure throughput
throughput_point* get_throughput_point(const std::string& name) {
// Lock the map of throughput points
_throughput_points_lock.lock();
// Search for a matching point
auto search = _throughput_points.find(name);
// If there is no match, add a new throughput point
if(search == _throughput_points.end()) {
search = _throughput_points.emplace_hint(search, name, new throughput_point(name));
}
// Get the matching or inserted value
throughput_point* result = search->second;
// Unlock the map and return the result
_throughput_points_lock.unlock();
return result;
}
/// Get or create a progress point to measure latency
latency_point* get_latency_point(const std::string& name) {
// Lock the map of latency points
_latency_points_lock.lock();
// Search for a matching point
auto search = _latency_points.find(name);
// If there is no match, add a new latency point
if(search == _latency_points.end()) {
search = _latency_points.emplace_hint(search, name, new latency_point(name));
}
// Get the matching or inserted value
latency_point* result = search->second;
// Unlock the map and return the result
_latency_points_lock.unlock();
return result;
}
/// Pass local delay counts and excess delay time to the child thread
int handle_pthread_create(pthread_t* thread,
const pthread_attr_t* attr,
thread_fn_t fn,
void* arg) {
thread_start_arg* new_arg;
thread_state* state = get_thread_state();
if (NULL == state) {
init_coz();
state = get_thread_state();
}
REQUIRE(state) << "Thread state not found";
// Allocate a struct to pass as an argument to the new thread
new_arg = new thread_start_arg(fn, arg, state->local_delay);
// Create a wrapped thread and pass in the wrapped argument
return real::pthread_create(thread, attr, profiler::start_thread, new_arg);
}
/// Force threads to catch up on delays, and stop sampling before the thread exits
void handle_pthread_exit(void* result) __attribute__((noreturn)) {
end_sampling();
real::pthread_exit(result);
abort(); // Silence g++ warning about noreturn
}
/// Ensure a thread has executed all the required delays before possibly unblocking another thread
void catch_up() {
thread_state* state = get_thread_state();
if(!state)
return;
// Handle all samples and add delays as required
if(_experiment_active) {
state->set_in_use(true);
add_delays(state);
state->set_in_use(false);
}
}
/// Call before (possibly) blocking
void pre_block() {
thread_state* state = get_thread_state();
if(!state)
return;
state->pre_block_time = _global_delay.load();
}
/// Call after unblocking. If by_thread is true, delays will be skipped
void post_block(bool skip_delays) {
thread_state* state = get_thread_state();
if(!state)
return;
state->set_in_use(true);
if(skip_delays) {
// Skip all delays that were inserted during the blocked period
state->local_delay += _global_delay.load() - state->pre_block_time;
}
state->set_in_use(false);
}
/// Only allow one instance of the profiler, and never run the destructor
static profiler& get_instance() {
static char buf[sizeof(profiler)];
static profiler* p = new(buf) profiler();
return *p;
}
private:
profiler() {
_experiment_active.store(false);
_global_delay.store(0);
_delay_size.store(0);
_selected_line.store(nullptr);
_next_line.store(nullptr);
_running.store(true);
}
// Disallow copy and assignment
profiler(const profiler&) = delete;
void operator=(const profiler&) = delete;
void profiler_thread(spinlock& l); //< Body of the main profiler thread
void begin_sampling(thread_state* state); //< Start sampling in the current thread
void end_sampling(); //< Stop sampling in the current thread
void add_delays(thread_state* state); //< Add any required delays
void process_samples(thread_state* state); //< Process all available samples and insert delays
std::pair<line*,bool> match_line(perf_event::record&); //< Map a sample to its source line and matches with selected_line
void log_samples(std::ofstream&, size_t); //< Log runtime and sample counts for all identified regions
thread_state* add_thread(); //< Add a thread state entry for this thread
thread_state* get_thread_state(); //< Get a reference to the thread state object for this thread
void remove_thread(); //< Remove the thread state structure for the current thread
static void* start_profiler_thread(void*); //< Entry point for the profiler thread
static void* start_thread(void* arg); //< Entry point for wrapped threads
static void samples_ready(int, siginfo_t*, void*); //< Signal handler for sample processing
static void on_error(int, siginfo_t*, void*); //< Handle errors
/// A map from name to throughput monitoring progress points
std::unordered_map<std::string, throughput_point*> _throughput_points;
spinlock _throughput_points_lock; //< Spinlock that protects the throughput points map
/// A map from name to latency monitoring progress points
std::unordered_map<std::string, latency_point*> _latency_points;
spinlock _latency_points_lock; //< Spinlock that protects the latency points map
static_map<pid_t, thread_state> _thread_states; //< Map from thread IDs to thread-local state
std::atomic<bool> _experiment_active; //< Is an experiment running?
std::atomic<size_t> _global_delay; //< The global delay time required
std::atomic<size_t> _delay_size; //< The current delay size
std::atomic<line*> _selected_line; //< The line to speed up
std::atomic<line*> _next_line; //< The next line to speed up
pthread_t _profiler_thread; //< Handle for the profiler thread
std::atomic<bool> _running; //< Clear to signal the profiler thread to quit
std::string _output_filename; //< File for profiler output
line* _fixed_line; //< The only line that should be sped up, if set
int _fixed_delay_size = -1; //< The only delay size that should be used, if set
/// Should coz run in end-to-end mode?
bool _enable_end_to_end;
/// Atomic flag to guarantee shutdown procedures run exactly one time
std::atomic_flag _shutdown_run = ATOMIC_FLAG_INIT;
};
#endif
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