46

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

okoman
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6 Answers6

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.

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Nik Reiman
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  • Didn't know that Boost provides timer functionality. Thank you :) – okoman Feb 11 '09 at 20:33
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    Or use the [HighResTimer](http://www.dre.vanderbilt.edu/Doxygen/Stable/ace/classACE__High__Res__Timer.html) from the [ACE](http://www.cs.wustl.edu/~schmidt/ACE.html) library. – lothar Apr 12 '09 at 02:00
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    @lothar: +1 for pointer to ACE library, thanks. The link you gave was stale, here's a new one: http://www.dre.vanderbilt.edu/Doxygen/Stable/libace-doc/a00227.html – BD at Rivenhill May 16 '11 at 16:02
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

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grieve
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    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) – bdonlan Jan 21 '11 at 17:57
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

Somesh Kumar
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tjd
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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
Martin G
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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.

Oliver N.
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1

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

Alan Turing
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