High resolution timer with C++ and Linux?
Asked Answered
C

6

47

Under Windows there are some handy functions like QueryPerformanceCounter from mmsystem.h to create a high resolution timer. Is there something similar for Linux?

Cantlon answered 11/2, 2009 at 20:24 Comment(1)
https://mcmap.net/q/20958/-c-cross-platform-high-resolution-timer (Cross-platform C++11 standard high resolution timer)Summer
P
31

It's been asked before here -- but basically, there is a boost ptime function you can use, or a POSIX clock_gettime() function which can serve basically the same purpose.

Purport answered 11/2, 2009 at 20:29 Comment(3)
Didn't know that Boost provides timer functionality. Thank you :)Cantlon
Or use the HighResTimer from the ACE library.Barouche
@lothar: +1 for pointer to ACE library, thanks. The link you gave was stale, here's a new one: dre.vanderbilt.edu/Doxygen/Stable/libace-doc/a00227.htmlSelfeducated
K
30

For Linux (and BSD) you want to use clock_gettime().

#include <sys/time.h>

int main()
{
   timespec ts;
   // clock_gettime(CLOCK_MONOTONIC, &ts); // Works on FreeBSD
   clock_gettime(CLOCK_REALTIME, &ts); // Works on Linux
}

See: This answer for more information

Kumamoto answered 11/2, 2009 at 20:30 Comment(1)
Of course, you need to be aware of the difference between CLOCK_MONOTONIC and CLOCK_REALTIME - the former has its zero-point set to something arbitrary at system boot, and as such is only useful for relative comparisons between two CLOCK_MONOTONIC measurements (but is unaffected by wallclock adjustments)Imminence
E
8

Here's a link describing how to do high-resolution timing on Linux and Windows... and no, Don't use RTSC.

https://web.archive.org/web/20160330004242/http://tdistler.com/2010/06/27/high-performance-timing-on-linux-windows

Estival answered 21/1, 2011 at 16:54 Comment(0)
C
5

With C++11, use std::chrono::high_resolution_clock.

Example:

#include <iostream>
#include <chrono>
typedef std::chrono::high_resolution_clock Clock;

int main()
{
    auto t1 = Clock::now();
    auto t2 = Clock::now();
    std::cout << "Delta t2-t1: " 
              << std::chrono::duration_cast<std::chrono::nanoseconds>(t2 - t1).count()
              << " nanoseconds" << std::endl;
}

Output:

Delta t2-t1: 131 nanoseconds
Costard answered 17/8, 2016 at 18:48 Comment(0)
P
1

I have nothing but this link: http://www.mjmwired.net/kernel/Documentation/rtc.txt

I'm pretty sure RTC is what you are looking for though.

EDIT

Other answers seem more portable than mine.

Pallaton answered 11/2, 2009 at 20:28 Comment(0)
M
1

For my money, there is no easier-to-use cross-platform timer than Qt's QTime class.

Mindy answered 4/7, 2011 at 21:44 Comment(0)

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