casa::PrecTimer Class Reference [OS_module]

Precision timer to measure elapsed times in a cumulative way. More...

#include <PrecTimer.h>

List of all members.

Public Member Functions
	PrecTimer ()
	Construct.
	~PrecTimer ()
	Destruct.
void	start ()
	Restart the timer.
void	stop ()
	Stop the timer.
void	reset ()
	Reset the timer to zero.
void	show () const
	Show real time on cout or a user supplied stream.
void	show (std::ostream &os) const
void	show (const String &) const
	Show real time on cout or a user supplied stream preceeded by the string parameter.
void	show (std::ostream &os, const String &prefix) const
double	getReal () const
	Get the real time (in seconds).
unsigned long long	getCount () const
	Get the total number of times start/stop is done.
Private Member Functions
void	print_time (std::ostream &, double time) const
Static Private Member Functions
static double	get_CPU_speed_in_MHz ()
Private Attributes
union {
long long   total_time
struct {
int   total_time_low
int   total_time_high
}
};
unsigned long long	count
Static Private Attributes
static double	CPU_speed_in_MHz

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Detailed Description

Precision timer to measure elapsed times in a cumulative way.

Intended use:

Public interface

Review Status

Test programs:

tPrecTimer

Synopsis

The PrecTimer supplements the Timer class. If offers a low-overhead and high-resolution interval timer for use on i386, x86_64, ia64, and powerpc platforms, using the processor's timestamp counter that is incremented each cycle. Put timer.start() and timer.stop() calls around the piece of code to be timed. Because the timer is cumulative, the total time of a particular piece of code can be timed.
Caution: Make sure that start() and stop() calls alternate, otherwise very strange times will be the result;

A timer can be started and stopped multiple times; both the average and total time, as well as the number of iterations are printed. The measured time is real time (as opposed to user or system time). The timer can be used to measure from 10 nanosecond to a century interval.

Multiple timers can be used in a nested way as long as each of them has independent (matching) start and stop calls.

The class is more or less a copy of the original written by John Romein at ASTRON, Dwingeloo, the Netherlands.

Example

Here's how to create a timer, start it (the 'mark' member function) and display a breakdown.

     PrecTimer ttimer;   // the timer is reset at construction time
     PrecTimer ctimer;
     ttimer.reset();     // if you want to reset the timer (not needed here)
     ttimer.start();     // start the total timer
     for (int i=0; i<n; ++i) {
       ... do something ..\.
       ctimer.start();   // start the calc timer
       ...do some calculation which will be timed..\.
       ctimer.stop();    // and stop it
     }
     ttimer.stop();
     ttimer.show (cout, "Total       ");
     ctimer.show (cout, "Calculations");

Definition at line 100 of file PrecTimer.h.

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Constructor & Destructor Documentation

casa::PrecTimer::PrecTimer

(

)

[inline]

Construct.

Definition at line 177 of file PrecTimer.h.

References reset().

casa::PrecTimer::~PrecTimer

(

)

[inline]

Destruct.

Definition at line 182 of file PrecTimer.h.

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Member Function Documentation

static double casa::PrecTimer::get_CPU_speed_in_MHz

(

)

[static, private]

unsigned long long casa::PrecTimer::getCount

(

)

const [inline]

Get the total number of times start/stop is done.

Definition at line 172 of file PrecTimer.h.

References count.

double casa::PrecTimer::getReal

(

)

const

Get the real time (in seconds).

void casa::PrecTimer::print_time	(	std::ostream &	,
		double	time
	)			const [private]

void casa::PrecTimer::reset

(

)

[inline]

Reset the timer to zero.

Definition at line 166 of file PrecTimer.h.

References count, and total_time.

Referenced by PrecTimer().

void casa::PrecTimer::show	(	std::ostream &	os,
		const String &	prefix
	)			const

void casa::PrecTimer::show

(

)

const

Show real time on cout or a user supplied stream.

void casa::PrecTimer::show

(

std::ostream &

os

)

const

void casa::PrecTimer::show

(

const String &

)

const

Show real time on cout or a user supplied stream preceeded by the string parameter.

void casa::PrecTimer::start

(

)

[inline]

Restart the timer.

Definition at line 186 of file PrecTimer.h.

References total_time, total_time_high, and total_time_low.

void casa::PrecTimer::stop

(

)

[inline]

Stop the timer.

Definition at line 260 of file PrecTimer.h.

References count, total_time, total_time_high, and total_time_low.

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Member Data Documentation

union { ... } [private]

unsigned long long casa::PrecTimer::count [private]

Definition at line 157 of file PrecTimer.h.

Referenced by getCount(), reset(), and stop().

double casa::PrecTimer::CPU_speed_in_MHz [static, private]

Definition at line 160 of file PrecTimer.h.

long long casa::PrecTimer::total_time

Definition at line 139 of file PrecTimer.h.

Referenced by reset(), start(), and stop().

int casa::PrecTimer::total_time_high

Definition at line 144 of file PrecTimer.h.

Referenced by start(), and stop().

int casa::PrecTimer::total_time_low

Definition at line 144 of file PrecTimer.h.

Referenced by start(), and stop().

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The documentation for this class was generated from the following file:

• casa/OS/PrecTimer.h