Jan, Omegamon has no way of attributing MVS overhead. It simply subtracts the RMF processor busy time from the interval time and reports the difference.
Being time-driven, WLM uses very little CPU on it's own behalf. In fact, as has been pointed out, when capping is in effect, IRD weight management is suspended. Bear in mind that there is an RMF on each LPAR, but there is only one PR/SM hypervisor. If I'm not mistaken, LPAR management time is over and above MVS uncaptured "overhead." Not much can be done about high RNI. If a new machine exhibits abnormally high overhead, or if an application's performance is severely degraded and you can't explain it any other way, type 113 sampling data might offer a clue. However, HIS sampling is not intended for use under normal operation. I would recommend asking an IBM technical support representative for guidance. db -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Jan Vanbrabant Sent: Thursday, February 21, 2013 3:34 AM To: [email protected] Subject: Re: ''MVS overhead'' (as indicated by OMEGAMON) Hi Dave & co-listers, 1° Is OMEGAMON capable of drilling down into "MVS Overhead" ? If not, how can further PD (Problem Detemination) be done? 2° Is the CPU-MF HIS approach based on SMF113 not too long-winded and over-doing? CPU-MF (HIS) NOT being a substitute for traditional performance nor capacity metrics. And it does NOT indicate either the capacity being achieved by the LPAR or processor 3° Where is "*phantom load*" (or a *"phantom" logical partition) * and "*cap(ping) pattern*" reported? IF reported. Or where can we find it? SG24-6472-03 System Programmer's Guide to Workload Manager (WLM) (last update 20 april 2010) (applies to zOS V1R8 - Maart 2008) http://www.redbooks.ibm.com/abstracts/sg246472.html 3.4 Soft capping (page 101 ... etc ...) 3.4.1 *Defined capacity* When WLM caps the logical partition, there are three possible scenarios: *1° The percentage share of the logical partition processing weight is equal to the percentage share of the defined capacity.* *(relative weight = defined capacity)* In this case, the capping is done at the logical partition processing weight. This is the best and recommended situation. 2° *The percentage share of the logical partition processing weight is greater than the percentage share of the defined capacity.* *(relative weight > defined capacity)* In this case, capping at the weight has no effect, because the logical partition has more MSU than allowed. To enforce the percentage share of WLC, PR/SM subtracts a certain number from the logical partition processing weight to match the desired percentage share and calculates a *"phantom" logical partition* that receives the remaining unused weight. This guarantees that other logical partitions are not affected by the weight management, because the total logical partition processing weight stays the same. * 3° The percentage share of the logical partition processing weight is lower than the percentage share of the defined capacity.* *(relative weight < defined capacity)* WLM defines a cap pattern that repeatedly applies and removes the cap at the logical partition processing weight. Over time, this looks as though the partition is constantly capped at its defined capacity limit. The *cap pattern* depends on the difference between the capacity based on the weight and the defined capacity limit. If the weight is small compared to the defined capacity, the capacity of the partition can be reduced drastically for short periods of time. This can cause performance to suffer. Therefore, we recommend to keep both definitions as close as possible. Where is "phantom load" or the "phantom logical partition" reported? (IF reported !?) Where is "cap(ping) pattern" reported? (IF reported !?) RMF ??? Is "cap pattern" part of the "MVS Overhead" ? Because WLM must be working like hell. Please, enlighten us. Jan ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
