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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef perf_jsperf_h
#define perf_jsperf_h
#include "jstypes.h"
#include "js/TypeDecls.h"
#include "js/Utility.h"
namespace JS {
/*
* JS::PerfMeasurement is a generic way to access detailed performance
* measurement APIs provided by your operating system. The details of
* exactly how this works and what can be measured are highly
* system-specific, but this interface is (one hopes) implementable
* on top of all of them.
*
* To use this API, create a PerfMeasurement object, passing its
* constructor a bitmask indicating which events you are interested
* in. Thereafter, Start() zeroes all counters and starts timing;
* Stop() stops timing again; and the counters for the events you
* requested are available as data values after calling Stop(). The
* object may be reused for many measurements.
*/
class JS_FRIEND_API(PerfMeasurement)
{
protected:
// Implementation-specific data, if any.
void* impl;
public:
/*
* Events that may be measured. Taken directly from the list of
* "generalized hardware performance event types" in the Linux
* perf_event API, plus some of the "software events".
*/
enum EventMask {
CPU_CYCLES = 0x00000001,
INSTRUCTIONS = 0x00000002,
CACHE_REFERENCES = 0x00000004,
CACHE_MISSES = 0x00000008,
BRANCH_INSTRUCTIONS = 0x00000010,
BRANCH_MISSES = 0x00000020,
BUS_CYCLES = 0x00000040,
PAGE_FAULTS = 0x00000080,
MAJOR_PAGE_FAULTS = 0x00000100,
CONTEXT_SWITCHES = 0x00000200,
CPU_MIGRATIONS = 0x00000400,
ALL = 0x000007ff,
NUM_MEASURABLE_EVENTS = 11
};
/*
* Bitmask of events that will be measured when this object is
* active (between Start() and Stop()). This may differ from the
* bitmask passed to the constructor if the platform does not
* support measuring all of the requested events.
*/
const EventMask eventsMeasured;
/*
* Counters for each measurable event.
* Immediately after one of these objects is created, all of the
* counters for enabled events will be zero, and all of the
* counters for disabled events will be uint64_t(-1).
*/
uint64_t cpu_cycles;
uint64_t instructions;
uint64_t cache_references;
uint64_t cache_misses;
uint64_t branch_instructions;
uint64_t branch_misses;
uint64_t bus_cycles;
uint64_t page_faults;
uint64_t major_page_faults;
uint64_t context_switches;
uint64_t cpu_migrations;
/*
* Prepare to measure the indicated set of events. If not all of
* the requested events can be measured on the current platform,
* then the eventsMeasured bitmask will only include the subset of
* |toMeasure| corresponding to the events that can be measured.
*/
explicit PerfMeasurement(EventMask toMeasure);
/* Done with this set of measurements, tear down OS-level state. */
~PerfMeasurement();
/* Start a measurement cycle. */
void start();
/*
* End a measurement cycle, and for each enabled counter, add the
* number of measured events of that type to the appropriate
* visible variable.
*/
void stop();
/* Reset all enabled counters to zero. */
void reset();
/*
* True if this platform supports measuring _something_, i.e. it's
* not using the stub implementation.
*/
static bool canMeasureSomething();
};
/* Inject a Javascript wrapper around the above C++ class into the
* Javascript object passed as an argument (this will normally be a
* global object). The JS-visible API is identical to the C++ API.
*/
extern JS_FRIEND_API(JSObject*)
RegisterPerfMeasurement(JSContext* cx, JS::HandleObject global);
/*
* Given a Value which contains an instance of the aforementioned
* wrapper class, extract the C++ object. Returns nullptr if the
* Value is not an instance of the wrapper.
*/
extern JS_FRIEND_API(PerfMeasurement*)
ExtractPerfMeasurement(const Value& wrapper);
} // namespace JS
#endif /* perf_jsperf_h */
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