CLOCKS_PER_SEC is a machine dependent macro, but not so machine dependent to recognize that my 32-bit windows box has dual processors. Not useful for benchmarking, is it.
clock is not the way to go. It is a crude estimation of processor time. On regular UNIX times(2) is the function to use -- cygwin does not seem to have it. I don't know if this helps, but: My cygwin reports $ ./chktime CLOCKS_PER_SEC = 1000 clock() = 31 clock() = 31 clock() = 31 clock() = 31 clock() = 31 clock() = 31 clock() = 31 clock() = 31 My 64-bit Fedora/Linux reports # ./chktime CLOCKS_PER_SEC = 1000000 clock() = 0 clock() = 0 clock() = 0 clock() = 0 clock() = 0 clock() = 0 clock() = 0 clock() = 0 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Norton Allen Sent: Tuesday, January 08, 2008 12:57 PM To: cygwin@cygwin.com Subject: Does clock() work? I am trying to write a benchmark application, and figured I'd use clock() for sub-second resolution timing, but I got non-sensical results. I check the cygwin archives, but the only mention I saw was that clock() didn't work on Win98. Here's my test code, chktime.c: #include <time.h> #include <unistd.h> #include <stdio.h> int main( int argc, char **argv ) { clock_t cur_time, cps = CLOCKS_PER_SEC; int i; printf( "CLOCKS_PER_SEC = %ld\n", cps ); for ( i = 0; i < 8; i++ ) { sleep(1); cur_time = clock(); printf( "clock() = %ld\n", cur_time ); } return 0; } and here's the output I get: Cygwin> ./chktime CLOCKS_PER_SEC = 1000 clock() = 171 clock() = 171 clock() = 171 clock() = 171 clock() = 171 clock() = 171 clock() = 171 clock() = 171 Cygwin> I would expect the clock() values to increase by approximately 1000 on each iteration. (Yes, the sleep() seems to be working, as the lines come out at about 1 Hz.) Is this a known problem? Do others get this result, or do I have a corrupted library? -Norton Allen -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/ -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
