Hi all This is a snapshot of a paper I wrote a couple of years ago.
May be it can help ... Unfortunately I could not attach the graph because of List rules but results using SMF 100 are just a little bit lower than using SMF 30 OR 72. Best regards Fabio DB2 overhead for MSTR, DBM1 and IRLM can be easily evaluated using SMF 30, 100 or 72 records. a) Using SMF 30 interval records (subtype 2 and 3); you have to select the records belonging to MSTR, DBM1 and IRLM address spaces and sum the CPU time provided in the SMF30ICS, SMF30ICU, SMF30HPT, SMF30IIP, SMF30RCT, SMF30CPS, SMF30CPT fields; b) Using SMF 100; you have to use the QWSAEJST and QWSASRBT fields. A section for each DB2 system address space is provided, so to get MSTR, DBM1 and IRLM overhead you have to sum the values corresponding to all of them2. Remember that these counters have been accumulated since DB2 was last started. So a de-accumulation step is required to get the numbers relative to the analyzed period of time. c) Using SMF 72 records requires a preliminary assignment of DB2 system address spaces to specific WLM service or report class. Then you have to: 1. select the records belonging to these classes; 2. normalize zAAP and zIIP service units, provided in the R723CIFA and R723CSUP fields, to standard CPUs speed multiplying respectively by the R723NFFI and R723NFFS coefficient (they normally have the same value) and dividing by 256; 3. subtract normalized zAAP and zIIP service units from the service units provided in the R723CCPU field; 4. convert TCB and SRB service units values in R723CCPU and R723CSRB to CPU seconds multiplying by the system service units per second value and dividing by the TCB and SRB coefficients (provided in the R723MCPU and R723MSRB fields); 5. sum the values obtained in the previous step to the values provided in the R723CIIT, R723CHST and R723CRCT fields. We applied all the methods described above and we calculated the DB2 System Address Spaces overhead using the following variables: • AS100OVH, based on SMF 100 records; • AS072OVH, based on SMF 72 records; • AS030OVH, based on SMF 30 interval records. The graph in Figure 1 allows us to compare the results we obtained. Only the “prime shift” hours, from 8am to 5pm, are presented. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + Fabio Massimo Ottaviani + EPV Technologies Technical Director + Skype: fabio.massimo.ottaviani + Mobile: +393406168088 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + IT Cost under Control + www.epvtech.com +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please consider the environment - do you really need to print this email? -----Messaggio originale----- Da: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] Per conto di Barry Merrill Inviato: giovedì 8 agosto 2013 19:27 A: IBM-MAIN@LISTSERV.UA.EDU Oggetto: Re: Differences between CPU values from SMF30 and DB2 stats In general, there will be very little CPU time recorded in the DB2 Address Spaces, except for the DDR address space, because CPU time consumed in DB2 is recorded in the address space OF THE CALLER, i.e., the Batch Job or the CICS region that called DB2, so the SMF 101 (DB2ACCT) data is the only safe source of who is consuming DB2 CPU time. Barry Herbert W. "Barry" Merrill, PhD President-Programmer MXG Software Merrill Consultants 10717 Cromwell Drive Dallas, TX 75229 <mailto:ba...@mxg.com> ba...@mxg.com <http://www.mxg.com> http://www.mxg.com - FAQ has Most Answers <mailto:ad...@mxg.com> ad...@mxg.com - invoices/PO/Payment <mailto:supp...@mxg.com> supp...@mxg.com - technical tel: 214 351 1966 - expect slow reply, use email fax: 214 350 3694 - prefer email, still works -----Original Message----- From: IBM Mainframe Discussion List [ <mailto:IBM-MAIN@LISTSERV.UA.EDU> mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Mike Bell Sent: Thursday, August 08, 2013 12:21 PM To: <mailto:IBM-MAIN@LISTSERV.UA.EDU> IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Differences between CPU values from SMF30 and DB2 stats There is a basic issue with DB2 statistics for CPU - they start with the first SQL statement. Everything that happens before that is not recorded in the DB2 cpu times. This is WAD. There used to be some presentations on what was included in DB2 cpu and why. I haven't looked for them in a long time. Maybe someone on DB2 listserv has a better memory or keeps better notes. Mike On Thu, Aug 8, 2013 at 8:39 AM, Charles Mills < <mailto:charl...@mcn.org> charl...@mcn.org> wrote: > Do you know that there is a DB2-specific mailing list where lots of > serious DB2 performance heavyweights hang out? > > I believe the enrollment process is to go to <http://www.idug.org> > www.idug.org and "join" IDUG. > > Charles > > -----Original Message----- > From: IBM Mainframe Discussion List [ <mailto:IBM-MAIN@LISTSERV.UA.EDU> > mailto:IBM-MAIN@LISTSERV.UA.EDU] > On Behalf Of Nguyen Duc > Sent: Thursday, August 08, 2013 3:45 AM > To: <mailto:IBM-MAIN@LISTSERV.UA.EDU> IBM-MAIN@LISTSERV.UA.EDU > Subject: Differences between CPU values from SMF30 and DB2 stats > > Dear all, > > I am a DB2 specialist , doing some measurements i just noticed that > there is a noticeable difference between DB2 CPU times i got from > SMF30, and the times i got from the DB2 statistics records (SMF100) > about the CPU consumption of DB2 address spaces. I submitted the > question to various performance specialists at IBM (authors of > presentations at CMG ...) but none of them noticed this before. > This is the second MVS site that i notice the differences , so i don't > think that there is a bug behind that. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send > email to <mailto:lists...@listserv.ua.edu> lists...@listserv.ua.edu with the > message: INFO IBM-MAIN > -- Mike ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to <mailto:lists...@listserv.ua.edu> lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to <mailto:lists...@listserv.ua.edu> lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
