ircd::prof: Reorg; deinline various; add comments.

include/ircd/prof.h

@@ -66,6 +66,7 @@ namespace ircd::prof::vg
 	struct enable;
 	struct disable;
 
+	bool enabled();
 	void dump(const char *const reason = nullptr);
 	void toggle();
 	void reset();
@@ -73,23 +74,50 @@ namespace ircd::prof::vg
 	void stop() noexcept;
 }
 
+// Exports to ircd::
 namespace ircd
 {
 	using prof::cycles;
 }
 
+/// Enable callgrind profiling for the scope
 struct ircd::prof::vg::enable
 {
-	enable() noexcept    { start(); }
-	~enable() noexcept   { stop();  }
+	enable() noexcept;
+	~enable() noexcept;
 };
 
+/// Disable any enabled callgrind profiling for the scope; then restore.
 struct ircd::prof::vg::disable
 {
-	disable() noexcept   { stop();  }
-	~disable() noexcept  { start(); }
+	disable() noexcept;
+	~disable() noexcept;
 };
 
+/// This suite of devices is intended to figure out when a system call is
+/// really slow or "blocking." The original use-case is for io_submit() in
+/// fs::aio.
+///
+/// The sample is conducted with times(2) which is itself a system call
+/// though reasonably fast, and the result has poor resolution meaning
+/// the result of at() is generally 0 unless the system call was very slow.
+///
+/// It is started on construction. The user must later call sample()
+/// which returns the value of at() as well.
+struct ircd::prof::syscall_timer
+{
+	uint64_t started, stopped;
+
+  public:
+	uint64_t at() const;
+	uint64_t sample();
+
+	syscall_timer() noexcept;
+};
+
+/// Frontend to times(2). This has low resolution in practice, but it's
+/// very cheap as far as syscalls go; x-platform implementation courtesy
+/// of boost::chrono.
 struct ircd::prof::times
 {
 	uint64_t real {0};
@@ -100,35 +128,8 @@ struct ircd::prof::times
 	times() = default;
 };
 
-/// This device intends to figure out when a system call is really slow
-/// or "blocking." The original use-case is for io_submit() in fs::aio.
-/// The sample is conducted with times(2) which is itself a system call,
-/// and the result has poor resolution meaning the result of at() is
-/// generally 0 unless the system call was actually slow.
-struct ircd::prof::syscall_timer
-{
-	uint64_t started
-	{
-		time_kern()
-	};
-
-	uint64_t stopped
-	{
-		0
-	};
-
-	uint64_t at() const
-	{
-		return stopped - started;
-	}
-
-	uint64_t stop()
-	{
-		stopped = time_kern();
-		return at();
-	}
-};
-
+/// Frontend to getrusage(2). This has higher resolution than prof::times
+/// in practice with slight added expense.
 struct ircd::prof::resource
 :std::array<uint64_t, 9>
 {
@@ -151,6 +152,7 @@ struct ircd::prof::resource
 	{}
 };
 
+/// Frontend to perf_event_open(2). This has the highest resolution.
 struct ircd::prof::system
 :std::array<std::array<uint64_t, 2>, 7>
 {
@@ -174,6 +176,10 @@ struct ircd::prof::system
 	{}
 };
 
+/// Type descriptor for prof events. This structure is used to aggregate
+/// information that describes a profiling event type, including whether
+/// the kernel or the user is being profiled (dpl), the principal counter
+/// type being profiled (counter) and any other contextual attributes.
 struct ircd::prof::type
 {
 	enum dpl dpl {0};
@@ -189,8 +195,8 @@ struct ircd::prof::type
 enum ircd::prof::dpl
 :std::underlying_type<ircd::prof::dpl>::type
 {
-	KERNEL,
-	USER
+	KERNEL  = 0,
+	USER    = 1,
 };
 
 enum ircd::prof::counter

ircd/ctx.cc

@@ -877,7 +877,7 @@ noexcept
 	{
 		timer.stopped?
 			timer.at():
-			timer.stop()
+			timer.sample()
 	};
 
 	if(likely(!total))

ircd/fs_aio.cc

@@ -896,7 +896,7 @@ try
 	};
 
 	#ifdef RB_DEBUG
-	stats.stalls += warning.timer.stop() > 0;
+	stats.stalls += warning.timer.sample() > 0;
 	#endif
 
 	assert(!qcount || ret > 0);

ircd/prof.cc

@@ -188,6 +188,201 @@ catch(const std::exception &e)
 	return nullptr;
 }
 
+//
+// prof::vg
+//
+
+namespace ircd::prof::vg
+{
+	static bool _enabled;
+}
+
+//
+// prof::vg::enable 
+//
+
+ircd::prof::vg::enable::enable()
+noexcept
+{
+	start();
+}
+
+ircd::prof::vg::enable::~enable()
+noexcept
+{
+	stop();
+}
+
+//
+// prof::vg::disable 
+//
+
+ircd::prof::vg::disable::disable()
+noexcept
+{
+	stop();
+}
+
+ircd::prof::vg::disable::~disable()
+noexcept
+{
+	start();
+}
+
+//
+// prof::vg util
+//
+
+void
+ircd::prof::vg::stop()
+noexcept
+{
+	#ifdef HAVE_VALGRIND_CALLGRIND_H
+	CALLGRIND_STOP_INSTRUMENTATION;
+	assert(_enabled);
+	_enabled = false;
+	#endif
+}
+
+void
+ircd::prof::vg::start()
+noexcept
+{
+	#ifdef HAVE_VALGRIND_CALLGRIND_H
+	assert(!_enabled);
+	_enabled = true;
+	CALLGRIND_START_INSTRUMENTATION;
+	#endif
+}
+
+void
+ircd::prof::vg::reset()
+{
+	#ifdef HAVE_VALGRIND_CALLGRIND_H
+	CALLGRIND_ZERO_STATS;
+	#endif
+}
+
+void
+ircd::prof::vg::toggle()
+{
+	#ifdef HAVE_VALGRIND_CALLGRIND_H
+	CALLGRIND_TOGGLE_COLLECT;
+	#endif
+}
+
+void
+ircd::prof::vg::dump(const char *const reason)
+{
+	#ifdef HAVE_VALGRIND_CALLGRIND_H
+	CALLGRIND_DUMP_STATS_AT(reason);
+	#endif
+}
+
+bool
+ircd::prof::vg::enabled()
+{
+	return _enabled;
+}
+
+//
+// syscall_timer
+//
+
+ircd::prof::syscall_timer::syscall_timer()
+noexcept
+:started
+{
+	time_kern()
+}
+,stopped
+{
+	0UL
+}
+{
+}
+
+uint64_t
+ircd::prof::syscall_timer::sample()
+{
+	stopped = time_kern();
+	return at();
+}
+
+uint64_t
+ircd::prof::syscall_timer::at()
+const
+{
+	return stopped - started;
+}
+
+
+//
+// time_*() suite
+//
+
+uint64_t
+ircd::prof::time_thrd()
+{
+	struct ::timespec tv;
+	syscall(::clock_gettime, CLOCK_THREAD_CPUTIME_ID, &tv);
+	return ulong(tv.tv_sec) * 1000000000UL + tv.tv_nsec;
+}
+
+uint64_t
+ircd::prof::time_proc()
+{
+	struct ::timespec tv;
+	syscall(::clock_gettime, CLOCK_PROCESS_CPUTIME_ID, &tv);
+	return ulong(tv.tv_sec) * 1000000000UL + tv.tv_nsec;
+}
+
+//
+// Interface (cross-platform)
+//
+
+uint64_t
+ircd::prof::time_real()
+{
+	return boost::chrono::process_real_cpu_clock::now().time_since_epoch().count();
+}
+
+uint64_t
+ircd::prof::time_kern()
+{
+	return boost::chrono::process_system_cpu_clock::now().time_since_epoch().count();
+}
+
+uint64_t
+ircd::prof::time_user()
+{
+	return boost::chrono::process_user_cpu_clock::now().time_since_epoch().count();
+}
+
+//
+// times
+//
+
+ircd::prof::times::times(sample_t)
+:real{}
+,kern{}
+,user{}
+{
+	const auto tp
+	{
+		boost::chrono::process_cpu_clock::now()
+	};
+
+	const auto d
+	{
+		tp.time_since_epoch()
+	};
+
+	this->real = d.count().real;
+	this->kern = d.count().system;
+	this->user = d.count().user;
+}
+
 //
 // resource
 //
@@ -730,115 +925,3 @@ ircd::prof::debug(std::ostream &s,
 
 	return s;
 }
-
-//
-// Interface
-//
-
-uint64_t
-ircd::prof::time_thrd()
-{
-	struct ::timespec tv;
-	syscall(::clock_gettime, CLOCK_THREAD_CPUTIME_ID, &tv);
-	return ulong(tv.tv_sec) * 1000000000UL + tv.tv_nsec;
-}
-
-uint64_t
-ircd::prof::time_proc()
-{
-	struct ::timespec tv;
-	syscall(::clock_gettime, CLOCK_PROCESS_CPUTIME_ID, &tv);
-	return ulong(tv.tv_sec) * 1000000000UL + tv.tv_nsec;
-}
-
-//
-// Interface (cross-platform)
-//
-
-uint64_t
-ircd::prof::time_real()
-{
-	return boost::chrono::process_real_cpu_clock::now().time_since_epoch().count();
-}
-
-uint64_t
-ircd::prof::time_kern()
-{
-	return boost::chrono::process_system_cpu_clock::now().time_since_epoch().count();
-}
-
-uint64_t
-ircd::prof::time_user()
-{
-	return boost::chrono::process_user_cpu_clock::now().time_since_epoch().count();
-}
-
-//
-// prof::vg
-//
-
-void
-ircd::prof::vg::stop()
-noexcept
-{
-	#ifdef HAVE_VALGRIND_CALLGRIND_H
-	CALLGRIND_STOP_INSTRUMENTATION;
-	#endif
-}
-
-void
-ircd::prof::vg::start()
-noexcept
-{
-	#ifdef HAVE_VALGRIND_CALLGRIND_H
-	CALLGRIND_START_INSTRUMENTATION;
-	#endif
-}
-
-void
-ircd::prof::vg::reset()
-{
-	#ifdef HAVE_VALGRIND_CALLGRIND_H
-	CALLGRIND_ZERO_STATS;
-	#endif
-}
-
-void
-ircd::prof::vg::toggle()
-{
-	#ifdef HAVE_VALGRIND_CALLGRIND_H
-	CALLGRIND_TOGGLE_COLLECT;
-	#endif
-}
-
-void
-ircd::prof::vg::dump(const char *const reason)
-{
-	#ifdef HAVE_VALGRIND_CALLGRIND_H
-	CALLGRIND_DUMP_STATS_AT(reason);
-	#endif
-}
-
-//
-// times
-//
-
-ircd::prof::times::times(sample_t)
-:real{}
-,kern{}
-,user{}
-{
-	const auto tp
-	{
-		boost::chrono::process_cpu_clock::now()
-	};
-
-	const auto d
-	{
-		tp.time_since_epoch()
-	};
-
-	this->real = d.count().real;
-	this->kern = d.count().system;
-	this->user = d.count().user;
-}