topic Re: Default clock resolution in Operating System - HP-UX

Default clock resolution

Rick Burge — Thu, 25 Jan 2001 18:38:58 GMT

Clock () indicates that the "potential" resolution is in microseconds but the default resolution is 10 milliseconds. Assuming that my machine is operating at a speed much higher than 1Mhz how do I set the default resolution to something better than 10 ms? My Visual C on my laptop at least gives me 1ms resolution.

Thanks,
Rick

Re: Default clock resolution

Andy Monks — Fri, 26 Jan 2001 09:50:54 GMT

clock(3c) is just a wrapper for times(2). Have a look at times(2) as that looks like it's in ticks (which is cpu dependent).

Or you look at pstat() which can get the same, but probably has too much overhead.

Andy

Re: Default clock resolution

Rick Burge — Fri, 26 Jan 2001 20:21:13 GMT

Thanks much for you reply... I had previously looked at this as an alternative only to discover that while it references a different definitions - CLK_TCK, it too is providing a 10ms resolution. What got me started on my question was the comment in clock() that indicates CLOCKS_PER_SECOND is defaulted at 10ms. This implies to me that perhaps the tick resolution could be set to a different value (within limits of course) by some system configuration parameter.

Ciao,
Rick

Re: Default clock resolution

Andy Monks — Sat, 27 Jan 2001 08:25:07 GMT

Looking at the time.h header file, you can see :-

#ifndef
#define CLOCKS_PER_SEC 1000000

Therefore, it looks like you might be able to override the value with your own.

Worth a try.