>Well, I disagree with such definition. IMHO CPU busy is "pattern" of >NOPs (No OPeration) and "usable" instructions. 1% busy simply means that >99% of cycles were filled with NOP, and only 1% of cycles were other >instructione were executed.
You can disagree with it all you like, but a job that is dispatched on a CPU is of no interest from a performance perspective. What matters is how long dispatchable work has to wait in the queue. >> HOWEVER, this depends explicitly on the relative >> dispatching priority of the work, so the 80% utilization would only be >> relevant to the lowest priority work in the system. >In fact dispatching priority denies you statement above or at least >distorts it. No, because it means that any work at DP=255 will not be delayed by lower priority work (beyond that work completing its dispatch interval). Therefore it is completely erroneous to assume that work at that high dispatching priority "sees" the overall utilization of the processor. Its dispatching priority ensures that only competitors at the same dispatching priority are relevant in establishing delays. A job at DP=245 will have to compete with all units of work at higher dispatching priorities, and therefore a higher utilization represents a higher probability of such lower priority work being subject to queuing delays. This is the basis by which workload manager takes actions in the first place, to ensure that higher importance goals are assigned higher dispatching priorities (if that's the primary delay) to ensure that their goals are more readily met (regardless of the overall utilization of the processor(s)). The overall CPU utilization represents the ongoing demand, while the relative utilization at each dispatching priority represents the level of competition experienced by the workload. Adam ---------------------------------------------------------------------- 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
