dry29.c gives the wrong number on macOS

[chris0e3]

On macOS ticks per second is 100.
However, dry29.c uses 60. (Through dry.c uses 100.)

dry29.c line: 43

#define HZ 60   /* 2.9BSD standard: 60 Hz (1/60 second ticks) */

This may explain the surprisingly low number (47,808,764) you reported for a Mac M2 Ultra.
While I get 61,300,308 with a much older i7 Macmini using dry.c.

The following works for me, though I don’t know how portable it is.

#include <limits.h>
#define HZ CLK_TCK

Also the output line Microseconds for one run through Dhrystone: 0.0 would be better updated to use Nanoseconds….

[davepl]

Thanks! From what I recall it differs beween BSD and NetBSD, went from 60 to 100. If the include works, that’s a great solution, I will use that, thanks! - Dave

…

On Nov 11, 2025, at 8:37 PM, chris0e3 ***@***.***> wrote: chris0e3 created an issue (davepl/pdpsrc#4) <#4> On macOS ticks per second is 100. However, dry29.c uses 60. (Through dry.c uses 100.) dry29.c line: 43 <https://github.com/davepl/pdpsrc/blob/e413294c6cd16dc4f364764a0d34e0682200bd50/bsd/dry/dry29.c#L43C9-L43C11> #define HZ 60 /* 2.9BSD standard: 60 Hz (1/60 second ticks) */ This may explain the surprisingly low number (47,808,764) you reported for a Mac M2 Ultra. While I get 61,300,308 with a much older i7 Macmini using dry.c. The following works for me, though I don’t know how portable it is. #include <limits.h> #define HZ CLK_TCK Also the output line Microseconds for one run through Dhrystone: 0.0 would be better updated to use Nanoseconds…. — Reply to this email directly, view it on GitHub <#4>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA4HCF3ZFGZDATGKUOZD7GT34K2Q7AVCNFSM6AAAAACL23XSWKVHI2DSMVQWIX3LMV43ASLTON2WKOZTGYYTIOBVG4YDINQ>. You are receiving this because you are subscribed to this thread.

[chris0e3]

A more general solution is:

#include <limits.h>
#ifdef CLK_TCK
#define HZ CLK_TCK
#else
#define HZ 60   /* 2.9BSD standard: 60 Hz (1/60 second ticks) */
#endif

PS It would be good to add an updated version of your published list of results to the repo.