On 2/1/2014 6:45 AM, Anne & Lynn Wheeler wrote:
MVS (and vm370) gets total cpu busy by clocking in and out of wait state
and subtracting it from elapsed. however vm370 does that also for every
other thing it does also ... so all the accounted for time plus wait
state time should come up to elapsed time (there may be tiny slop doing
the clock instructions ... or if PR/SM underneath is doing something)
the detailed MVS capture ratio discussions imply that MVS isn't even
bothering to do the clock accounting for large parts of the kernel (and
in some cases has been as high as 60%).
Modern operating systems use the System z Extract-CPU-Time Facility,
which accumulates accurate execution time, in cooperation with PR/SM,
without any "slop."
--
Edward E Jaffe
Phoenix Software International, Inc
831 Parkview Drive North
El Segundo, CA 90245
http://www.phoenixsoftware.com/
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