Capping

Capping is a strategy that has been available for a long time to reduce CPU consumption, and hopefully mainframe costs. In this issue, we're taking a closer look at capping.

Many sites we've seen don't use capping. Often this is because they are afraid of the impact of limiting CPU. In fact many have tried capping and been 'burnt' as the CPU constraints have blown out response times, batch windows and the number of user complaints. In our management section, we show how capping is not necessarily that bad, and can be implemented without impacting users at all.

In this issue, we're including two technical articles. The first follows on from our management article, and details steps to follow to implement capping without the pain felt by many.

In the second, we show how we convert from CPU seconds to MSUs, MIPS and four-hour rolling average MSUs.

We hope you enjoy this issue.

management: Capping: It's Really Not That Bad

A few months ago, I was at one site and mentioned capping. The comments I got back were things like "we can't kill our application's response times." And this is a typical response: people relate capping with end-user pain. But it doesn't have to be like this.

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technical: How to Implement Capping Without Pain

A few years ago, I saw a client implement capping. Unfortunately, they were too aggressive, and affected their users. Compile jobs started to take hours, response times were increased, and batch schedules took more time, affecting production processing. Such 'horror stories' can scare people away from capping. But it doesn't have to be this way. In fact, it shouldn't. So how can we implement capping to maximize savings, without impacting our critical systems and services?

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technical: Converting CPU seconds to MSUs and MIPS

A lot of my consulting work involves reducing CPU usage to save my clients money. As part of this work, I need to estimate how much money any recommendations I make will save. I also need to measure how much money I actually saved once the recommendation has been implemented. Almost everyone pays by MSU, four-hour rolling average MSU (4HRA MSU), or MIPS. So, I need to convert CPU seconds saved into MIPS/MSU for whatever I'm targeting: a batch job, CICS region, Websphere MQ channel initiator etc. Here's how I do it.

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