Work Management & Performance Chapter 14

Overview The AS/400 combines the pieces of Managing Devices, Working with Jobs, and Working with Subsystems to run programs Pieces fit together – performance testing

What makes a job run? 6 necessary things: Devices Job Descriptions Job Classes Job Queues Subsystems with: Routing entry(s) Job queue entries – batch SBS Workstation entry(s) – interactive SBS Communication entry(s) – communication SBS A valid user ID or password 6 necessary things:

How the AS/400 runs Interactive Jobs Batch Jobs WS device known Valid sign-on SBS with job description and class WSE Routing Entry Batch Jobs How batch jobs are started: SBMJOB Communication PGM start request Auto-start jobs Pre-start jobs

How the AS/400 runs Communication Jobs A hybrid between interactive and batch jobs Remote system start Communication entry needed

Subsystems QBASE and QCTL SYSOPR should: QCMN QINTER QBATCH QSPL

Performance AS/400 has ability to constantly “tune” resources while jobs are running Document all efforts

Automatic Performance Tuning Two system values QDYNPTYSCD prevents gobbling resources QPFRADJ manages pool memory allocations Manual monitoring is still a good idea

Why Manually Monitor? DPS is quick to reset changes priorities after they have been lowered SYSOPR may want it low SYSOPR may want a PGM to be a “hog” Sometimes user response-time complaints are due to transmission time across a busy or large LAN. (AS/400 performance tools don’t address this because it takes place outside the AS/400)

Emergencies – What do I do? An operator should be concerned with 2 areas: Overall CPU % Over 100% indicated by ++++ CPU % for individual jobs

WRKACTJOB

Why is CPU % high? 3 Reasons Programs are complex Page faulting is causing a lot of extra disk IO Overall load on the system (# of jobs) is too high

Recommendations Vs. Reality IBM recommends: below 70% for single-processors Below 81% for a four-way processor Systems without noticeable performance problems will typically run in the 90% range Remember: CPU utilization over 90% gets hammered from excessive seize/lock conflicts

What Next? CPU % over 90% - even if normal - continue searching for problem within the AS/400 CPU % good (approx 75%), hang-up may be due to lost device on LAN Response time problem + low CPU % Suspect LAN

Work With Active Jobs Example Largest CPU % - F16 re-sequences by specified column Some programs need a lot of “horsepower” Confirm big jobs are necessary (while holding - 3) If necessary, lower the job priority (higher #)

Problem still exists? WRKSYSACT (Work System Activity) Screen refreshes every five seconds System tasks and their CPU % is displayed Don’t normally appear on WRKACTJOB screen Cancel the user job and the system tasks will go with it

Emergency Aftermath New priorities require time to take affect Recovery period could cause worse damage LAN failure – disconnect users, sessions dumping logs and cleaning up after themselves lots of activity Announcements – “Sign back on” Performance will die – 15 to 45 minutes

TIPS Develop guidelines for performance emergencies Always use Performance tuning Monitor performance during busiest time Modify system parameters (changing activity levels or memory) during less busy times REMEMBER: Monitoring is an ongoing process If the System Operator has the AS/400 properly tuned, performance emergencies are less likely to occur

TIPS (Cont.) Performance Tools/400 has powerful data-collecting and reporting tools STRPFRMON ADDPFRCOL ANZPFRDTA PRTTNSRPT Best/1 is a built-in capacity-planning product Use SETOBJACC to preload entire files into dedicated pools for certain kinds of processing

AS/400 Servers Tuned to favor batch processing, leave them that way A few WS will make the interactive CPU % go to 10% and then nothing will run well IBM recommends less than 2% of the interactive CPU %