[C/C++] pause and cpu usage

Hyakutake · 02-15-2007, 04:43 PM

Hello all.

When doing some programming I wanted check/alter some variable every 3 seconds. The thing is that CPU usage is always at 100%.

How can I avoid/bypass this CPU consumption without using the command system() to call sleep XXs?

Thanks.

vargadanis · 02-15-2007, 07:39 PM

you can use ulimit if you want. That limits the resources that the process can access.

tuxdev · 02-15-2007, 08:30 PM

sleep() is also a system call. Don't count on it if you need it to come back in exactly 3 seconds.

Hyakutake · 02-16-2007, 07:47 AM

vargadanis: The idea was the program to itself standby for a certain amount time without the need to use some other program.

tuxdev: The time to come back dosent need to be so precise, arround 3 secs is fine.

So a c/c++ program always works at 100% CPU usage? Isn't this an efficiency problem?

I cant make some program to keep it running in background because it takes all CPU power.

matthewg42 · 02-16-2007, 08:16 AM

There's a sleep call defined in unistd.h - calling the sleep program with system() is not a good method. How do you think that program implements the sleeping anyhow?

There's also usleep and nanosleep for more precise sleep duration requests. As tuxdev said, don't rely on it to be very accurate (e.g. timing the movement of the fuel rods into and out of the reactor).

Hyakutake · 02-17-2007, 07:29 AM

Thanks matthewg42 that is what I wanted.

Thanks all who have replied.