Author Archives: Martin Packer

(Originally posted 2011-07-07.) It’s a popular suggestion that what separates the truly exceptional person from the rest of us is 10,000 hours of "practice". In book form I’ve seen it twice – in Matthew Syed’s "Bounce" and in Malcolm Gladwell’s "Outliers". Actually, to be fair, Matthew acknowledges his original source so that’s actually only oneContinue reading “10,000 Hours Doing WHAT?”

(Originally posted 2011-07-05.) As you probably know Hardware Data Compression has been supported by MVS and IBM mainframes for around 20 years. In several recent batch studies I’ve conducted it’s been evident in a widespread way. (In this post I’m not talking about DB2 compression of either flavour or VSAM compression – though some ofContinue reading “Recent Experiences With Hardware Data Compression”

(Originally posted 2011-07-02.) Following on from The Best Sort Is The One You Don’t Do here’s another reason for eliminating sorts. I think it’s worth a post in its own right. (In this post, again, I’m talking about resequencing passes over data – not copying or merging.) With a sort it’s possible the last recordContinue reading “Another (Perhaps Obvious) Reason For Avoiding Unnecessary Sorts”

(Originally posted 2011-07-02.) Have you ever had the suspicion a sort was unnecessary in your batch? I bet you have. In recent Batch Performance studies I’ve had the suspicion that many of the sorts are unnecessary: Either they should be merges or not done at all. But how do you prove it?  But first, whatContinue reading “The Best Sort Is The One You Don’t Do”

(Originally posted 2011-06-29.) This may be stating the obvious – but I wonder to whom it actually is obvious… I’ve been doing quite a lot of work with batch job timings and CPU recently. (Everything I’m about to say is equally true of steps.) It’s interesting to think about the effects of faster engines versusContinue reading “It Depends: SMF 30 Job Timings And CPU Time”

(Originally posted 2011-07-19.) Here’s another neat piece of algebra: A technique for summing series. You know what b – a + c – b + d – c is. Right? Suppose I were to write the same sum as: (b – a) + (c – b) + (d – c) The answer is still dContinue reading “Memory Breakdown in Firefox”

(Originally posted 2011-06-22.) A need has arisen for pretty printing XML. This post includes some Python code to do it. I’ve been working with the OpenOffice.org ODP presentation file format recently: I want to generate presentations from application code. An ODP file is a structured zip file. Among other items it contains an XML fileContinue reading “Pretty Printing XML in Python”

(Originally posted 2011-06-21.) Reading Now Your Embarrassing/Job-Threatening Facebook Photos Could Haunt You For Seven Years I think they’ve missed a point or two. Points which may be incidental to the thrust of the article but nonetheless are important ones: Who’s to say what’s embarrassing or job-threatening? Some things are obvious: In the post they talkContinue reading “A Comment on “Now Your Embarrassing/Job-Threatening Facebook Photos Could Haunt You For Seven Years””

(Originally posted 2011-06-12.) Here’s the first-pass abstract slide for "I Know What You Did Last Summer". I’d be interested in your thoughts on it… What’s The Point Of This Presentation? So, it’s got a "tongue-in-cheek" title but what’s it all about? I think one of the least appreciated aspects of z/OS and its middleware isContinue reading “I Know What You Did Last Summer – Abstract”

(Originally posted 2011-05-29.) At one level Performance and Capacity Management and Systems Investigation are clearly linked: They share the same data. Or much of it at least. But I think they’re linked in another way, too. Over the past few years I’ve gradually shifted emphasis towards Systems Investigation. But this has only been a slightContinue reading “Capacity, Performance and Systems Investigation”