i have a problem about PIT interrupt in mp3 project

In the systime.c

#define TCK  1000                           /* Timer Clock  */
#define PIV  ((MCK/TCK/16)-1)               /* Periodic Interval Value
*/

in the board:

#define MCK   48054857

so the PIV value is 3003.7 hz so interrupt will be
at every about 0.3 ms not 1 ms that mention it in comment.

/*  TIME.C:  Time Functions for 1000Hz Clock Tick

is comment is true?
or did i go in fulse?

also in systime_isr:
  if (systime_value % 16 == 0)
      process_keys();

is it true for 10 ms run the process_keys()?(comment 10 ms in control.c)
i want to know how run process_keys() for every 10 ms?
thanks.