Hello,

I would like to know, how can I measure time so as it always gives me
the difference between "now" and "start_of_process/thread" time,
regardless of whether the process/thread is running, sleeping or doing
whatever else...
I don't need a high accuracy resolution, milliseconds will be enough.

To what I know, both clock() and clock_gettime() (with id
CLOCK_PROCESS_CPUTIME_ID or CLOCK_THREAD_CPUTIME_ID) provide "correct"
results only in case of running process/thread. That means, whenever I
use a (nano)sleep(), the results are going to be affected by that.

Well, and I need to note that using gettimeofday() or similar
functions is not convenient, since the system time can be changed at
any time of my app running.

Thanks a lot in advance.

kakofony <marcel.balas@gmail.com> writes:
> I would like to know, how can I measure time so as it always gives me
> the difference between "now" and "start_of_process/thread" time,
> regardless of whether the process/thread is running, sleeping or doing
> whatever else...
> I don't need a high accuracy resolution, milliseconds will be enough.
>
> To what I know, both clock() and clock_gettime() (with id
> CLOCK_PROCESS_CPUTIME_ID or CLOCK_THREAD_CPUTIME_ID) provide "correct"
> results only in case of running process/thread. That means, whenever I
> use a (nano)sleep(), the results are going to be affected by that.
>
> Well, and I need to note that using gettimeofday() or similar
> functions is not convenient, since the system time can be changed at
> any time of my app running.

Provided that you can 'live as a timeless island', which is likely,
given your statement above, use CLOCK_MONOTONIC.

On 2009-03-24, kakofony <marcel.balas@gmail.com> wrote:
> Hello,
>
> I would like to know, how can I measure time so as it always gives me
> the difference between "now" and "start_of_process/thread" time,
> regardless of whether the process/thread is running, sleeping or doing
> whatever else...

> I don't need a high accuracy resolution, milliseconds will be enough.

> To what I know, both clock() and clock_gettime() (with id
> CLOCK_PROCESS_CPUTIME_ID or CLOCK_THREAD_CPUTIME_ID) provide "correct"
> results only in case of running process/thread. That means, whenever I
> use a (nano)sleep(), the results are going to be affected by that.
>
> Well, and I need to note that using gettimeofday() or similar
> functions is not convenient, since the system time can be changed at
> any time of my app running.

#include <time.h>

struct timespec ts;
clock_gettime(TIME_MONOTINIC,&ts);

I forgot to thank you. MONOTONIC works great.