I think you misunderstand the difference between microseconds and milliseconds.
sas On Mon, Jan 25, 2021 at 12:35 PM Eric Erickson <[email protected]> wrote: > I'm working on some code that tries to detect a loop in a subtask by > examining the LCCAWTIM value for each CPU. My detector task runs in an STC > that wakes up every .5 seconds and trolls through the LCCA Vector > calculating deltas of wait time between iterations. > > The routine that retrieves the LCCAWTIM runs on a half second timer. So I > would expect that the wait time delta for any CPs to be less than .5 > seconds. But deltas between the runs shows a value that > significantly exceeds .5 seconds (or 500 microseconds). > For example: > > On a pass through the routine, we have the LCCAWTIM values of > > Iteration 1 - 000e3134 9bba4d26 > Iteration 2 - 000e3134 bfb14032 - Delta - 00000000 23f6f30c - > Iteration 3 - 000e3134 d1ed1c5a - Delta - 00000000 123bdc28 > > According to the documentation LCCAWTIM is a double word value where bit > 51 represents 1 microsecond. To convert to microseconds, we lop off the > lower 3 nibbles (bits 52-63), now .5 seconds is only x'1f4' microseconds so > I would expect all the deltas to be x'1f4000' or less. > > Now the first delta converted to microseconds yields 23f6f or 147311 or > 147 seconds which is considerably longer than the 500 microseconds. The > second delta is better at 123bd (74685) but still at 74 seconds is way > longer than the .5 seconds that the timer is cycling. > What is interesting is that a test run that uses multiple tasks/jobs I do > get zero and near zero deltas between iterations. > > What am I missing here? > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
