John, On a related matter: I seem to remember that there is a way to use TIMEUSED so that it has *significantly* less overhead, which would be important for a "profiler" use case. I'm not sure, but I recall that it has something to do with BRANCH= and ECT=.
If anyone knows the details on this, I would appreciate any info. Kirk Wolf Dovetailed Technologies http://dovetail.com On Thu, Feb 3, 2011 at 9:06 AM, john gilmore <[email protected]> wrote: > Mr Butz writes: > > | I am just subtracting the before and after microseconds portion ignoring > date and time > > Consider a four-position decimal counter that currently has the value 99, > i.e., > > | 0 | 0 | 9 | 9 | > > Now save the low-order two digits, 99, and add 7 to the counter, obtaining > > | 0 | 1 | 0 | 6 | > > Saving the low-order two digits again yields 06. Then the subtraction 06 - > 99 yields a difference of -07, i.e., nonsense. > > Use the STCKF instruction, which 1) is a faster, lower-overhead one and 2) > stores binary zeros to the right of the position that is being incremented. > > Shift your STCKF values right to eliminate these insignificant binary > zeros. Then consult your PrOp again with some care, reconsidering how > properly to interpret differences in these shifted values. > > The notion that an STCKx value has separate date, time (hours?), and > microsecond fields is just wrong. It is a counter that has, conceptually, > been incremented by one for each elapsed clock unit since midnight 1899 > December 31. You may discard precision on the right; but you cannot ignore > leftmost, higher-order bits in any circumstances. > > John Gilmore Ashland, MA 01721-1817 USA > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: GET IBM-MAIN INFO > Search the archives at http://bama.ua.edu/archives/ibm-main.html > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
