Comments on: Profiling Code Using clock_gettime

By: mezzo

mezzo — Wed, 19 Aug 2009 11:42:19 +0000

Hi Guy,
I found your tutorial very useful,thanks a lot,.
I have a problem, I’am implementing a timers on embedded system,first a implemented it using system Time, but this was not good since systme time can be changed a t any moment and this may fail all timer.. So I decided to use CPU time based on your tutorial with clock_gettime, but first pb ::: CLOCK_PROCESS_CPUTIME_ID undeclared , I’am using C language on FREEBSD5.3 ,have you any idea ?!
thanks a lot !

By: Guy

Guy — Sun, 09 Aug 2009 19:13:25 +0000

@lordamit, I’ve deleted the previous comment, you’re welcomed.

By: lordamit

lordamit — Sat, 08 Aug 2009 17:20:18 +0000

Guy Been searching for something like this for the last 3 days.
you are a life saver
And once again, thanks a lot.
(please remove the previous comment, i gave the wrong link for website)

By: Chris

Chris — Thu, 09 Jul 2009 00:40:12 +0000

OK I got it I have the negative one case….

By: Chris

Chris — Thu, 09 Jul 2009 00:14:07 +0000

Hello to all,
I am trying to profile a code with different tests but they are similar to each other.I run clock_gettime repeatly and all tests have around 0.3 sec and sometimes I get 3.3 sec which is not normal.And when I try the same tests without the loops I get the normal around 0.3 sec.I tried to put sleep in the loop but nothing happens.May someone explain this to me.

Thanks in advance.

By: soji

soji — Tue, 07 Jul 2009 16:03:46 +0000

very helpful.

By: Profiling Code Using clock_gettime « Look here first!

Profiling Code Using clock_gettime « Look here first! — Mon, 06 Jul 2009 16:31:22 +0000

[...] Code Using clock_gettime By chris Find a good explanation here written by Guy [...]

By: Guy

Guy — Sat, 28 Mar 2009 18:51:17 +0000

@Neil: Take a look at QueryPerformanceCounter and QueryPerformanceFrequency it should be fairly close to clock_gettime. I don't know a way in Windows to get the actual CPU time spent on a process (or several). @Tim: Are you sure your system implements CLOCK_MONOTONIC? According to the posix specification, support for CLOCK_MONOTONIC is optional. It looks to me that you use clock_gettime correctly, maybe try to make some real work instead of sleep to see if it changes something.

By: Tim

Tim — Fri, 27 Mar 2009 22:05:21 +0000

This is a nice tutorial.. Can we use CLOCK_MONOTONIC? when i tried to use it in a loop with 3 seconds sleep i always get the same time..

int main()
{
struct timespec now;
while(1)
{
void clock_gettime(CLOCK_MONOTONIC, &now);

printf(“Seconds is %u\n”, now.tv_sec);
printf(“Nano Seconds is %u\n”, now.ntv_sec);

sleep(3);
}

return 0;
}

By: Neil

Neil — Fri, 27 Mar 2009 19:51:30 +0000

Hi Guy,

great article.
Do you know a way to do the same thing on Windows?
I have to measure the CPU-Time (not only elapsed time) of several processes at µs-precision.

Regards,

Neil