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LongEx Mainframe Quarterly - November 2011

opinion: A Consulting Example: Reducing CPU Consumption

Today I'm feeling a little smug. I've just finished an assembler program change that will save my customer around 240 MIPS. Not bad for a few days work.

I'm currently working on a project to cut our customer's CPU use. When paying for software licensing or outsourced processing by the CPU second, MIP or MSU; savings of around 240 MIPS can be very attractive. And this wasn't the only saving I found. Over the past few weeks, I've dug up about 700 MIPS of savings for this one customer.

This particular project is based around Paris, and is a joint effort with our partner CPT Global - an opportunity to use long-neglected French language skills. In addition to that 700 MIPS of z/OS and CICS systems savings, CPT Global have found far more from analysing databases and applications. Their analysis of our customer's software licensing agreements has also found a few things that have surprised our customer. Looking at the mainframe software portfolio for other savings may be the next step.

I've been working on this project for around 6 weeks. The first couple of days were spent familiarising myself with the customer's environment: software installed, versions used, hardware setup and how it all works together. During this time, I also transferred some SMF records to my PC, and processed them to find the big CPU users. This gave me my hit list.

From this list, I started digging deeper. Over many years working in the industry, I have built up a standard list of CPU savers. These cover such diverse systems as IMS, CICS, Websphere Application Server, as well as z/OS itself. I will also look for other potential areas. Customer will often have software that I haven't seen before, and I'll spend some time getting to know it, and look to see if anything can be improved. This particular customer had a data transfer package that was particularly interesting.

When analysing the environment, I will also look for things out of the ordinary. For example for this customer, the Catalog address space had an unusually high CPU consumption, and GRS was also a little suspicious. Seeing something out of the ordinary, I will investigate further using any tool that the customer has, as well as the standard z/OS tools and utilities. For my assembler program I used the standard SMF records kept, as well as Compuware STROBE and BMC MAINVIEW for z/OS. CPT also brought Macro 4 Expetune to the party.

Once I had found the target assembler program, I worked through the source for ways to improve it. Some assembler can be complicated, and take a while to understand. I may also talk to anyone with experience with the code to see why things were done. In this case, I moved a few modules into one, and modified processing that not only reduced CPU usage, but also cut Catalog and GRS use.

The other savings found were from a wide range of sources. CICS SIT options, DFHSM processing options, housekeeping JCL, and batch scheduling all contributed.

Like many consultants, my customers always get 'value-add' benefits for free. So I'll hand over anything I find that will help them, but which may not save any CPU. For this customer, I detected a looping system that greatly increased CPU consumption over a two week period, and some production batch jobs with no automatic monitoring of return codes. For other clients I have found security issues, and ways to improve performance without reducing CPU use.

This customer isn't the first to benefit from this type of project. A previous customer gained over 250 MIPS from changing Tivoli Storage Manager parameters, z/OS settings and some C/Assembler code. Similar savings for another were found from AF/Operator changes. And REXX program changes, JCL re-scheduling and reworking of one assembler module took care of a third.

Projects to cut CPU usage are just one of a range that Longpela Expertise does. For these projects we often work with CPT Global, who specialise in this area. Starting with a short initial phase over a couple of weeks, we quickly identify and quantify potential savings, and hand some over immediately to pay for that first phase. The second phase runs for a few weeks, and is really where the savings are identified. Customers receive detailed documents for all recommended changes - what they are, how much they save, risks and rewards, and any supporting documentation. Once implemented, we compare CPU measurements before and after to confirm the savings.

The really good news for our customers is the bottom line. All work, both from Longpela Expertise and CPT Global, will end up costing them nothing. Not one cent. We're certainly not working there for free, but the savings found will cover the costs many times over. A win-win situation.

David Stephens

LongEx Quarterly is a quarterly eZine produced by Longpela Expertise. It provides Mainframe articles for management and technical experts. It is published every November, February, May and August.

The opinions in this article are solely those of the author, and do not necessarily represent the opinions of any other person or organisation. All trademarks, trade names, service marks and logos referenced in these articles belong to their respective companies.

Although Longpela Expertise may be paid by organisations reprinting our articles, all articles are independent. Longpela Expertise has not been paid money by any vendor or company to write any articles appearing in our e-zine.

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