question on timing results

[Matthew Saltzman]

On Wed, 8 Jun 2005, Matthew Miller wrote:

> On Wed, Jun 08, 2005 at 06:40:34AM -0700, Globe Trotter wrote:
>> utilization. Unless I misunderstood the documentation, clock() provides
>> the processor time and so the difference between clock() at the beginning
>> of the call to an algorithm and the end would provide me with the CPU time
>> elapsed. However, if for some reason the processor was running at 75% or
>> whatever, my reported time would be affected, and hence there would not
>> really be a fair comparison. Does anyone have any ideas/suggestions as to
>> how I may settle this issue?
>
> clock() returns an approximation of the CPU time used by the actual process,
> so while load from other programs is a factor (particularly since it'll make
> your program wait for IO, etc.) it should do basically what you want.

Also check out the times(2) facility.  It's not ISO C, but it is POSIX and 
it has some advantages over clock(3).

-- 
 		Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs