bonasso bonasso@traclabs.com writes:

The RAPs system I'm running in abcl makes extensive use of the difference between two sequential get-internal-real-time calls. But I get significantly different results in abcl than in acl.

Here's an example:

In acl:

CL-USER(24): (setf foo (/ (get-internal-real-time)(float internal-time-units-per-second))) 8212185.5 CL-USER(25): (setf bar (/ (get-internal-real-time)(float internal-time-units-per-second))) 8212195.0 CL-USER(26): (- bar foo) 9.5 ;; nine+ seconds

In abcl: CL-USER(15): (setf foo (/ (get-internal-real-time)(float internal-time-units-per-second))) 1.40157018E9 CL-USER(16): (setf bar (/ (get-internal-real-time)(float internal-time-units-per-second))) 1.40157018E9 CL-USER(17): (- bar foo) 0.0 ;; 0 seconds

Thus, lots of time has to elapse between the calls before any difference is produced. (/ (get-internal-real-time)(float internal-time-units-per-second)) is the primitive time call used in the RAPs system.

Of course the first thing I noticed is that the single floats in acl don't have the E notation. Is there a setting in abcl I can use to get the same behavior as in acl, or is there another problem going on?

(get-internal-real-time) => 1401731099641, that's too big to be represented precisely as a single float. double float will work better. And better divide by internal-time-units-per-second before doing division. Even better would be to avoid converting into floats.