(Originally posted 2007-03-22.)

Here’s a nice picture from the Minding the Planet blog:

(Originally posted 2007-03-20.)

My good friend Linda August (of the IBM Washington Systems Center and previously of the global Performance Management team I was a member of) has written a very good paper (and an accompanying presentation she gave at SHARE in February).

The theme is highly topical: The management of uniprocessor LPARs. Topical because of the increased uniprocessor speed of the z990 and particularly the z9 processor families, which is leading customers to want to define LPARs with perhaps only a single logical engine.

It’s a thumpingly good read, covering a number of topics in the general areas of

• Changes in ready dispatcher to help SRM run work more efficiently in general
• WLM policy and MVS settings to help manage uniprocessor environment
• Managing CPU-intensive work
• z/OS functions which override WLM assigned dispatching priorities

The above list taken direct from her agenda foil.

The paper goes all the way back to the MVS/ESA “Reduced Pre-emption” line item. But it contains information about changes over all the years since. There are things in the paper and presentation that I didn’t know about – but I wouldn’t claim to be “omniscient in detail”.

You can get the paper from here. If questions or comments arise I’ll either handle them myself or point Linda to them. So do feel free to comment on the paper here.

(Originally posted 2007-03-20.)

I guess I must be part of the “ungrateful peasant” generation of computer geeks…

I never really liked FORTRAN. And now John Backus who led the team that developed it is dead.

For me the elegance of other languages biased my view – but that’s to miss the point: FORTRAN preceded them. And with all such pioneers elegance of form is often lacking.

I did have some practical acquaintance with FORTRAN: In 1984, when doing my final year Physics project I used it to do the “heavy lifting” (and an Acorn Atom to do the graphical lightweight display stuff). UCL at that time had a licence for the NAG set of mathematical libraries. As my project involved numerical integrations to solve Schrödinger’s Equation (in only 1 dimension) I turned to the NAG libraries. To use them I had to use FORTRAN. My practical experience of programming at that time had, to be fair, consisted of a mixture of Z80 Assembler, BASIC, and a home-grown programming language at “gap year” employer. So I think I had a reasonable view.

And that view, whether reasonable or not, was that FORTRAN was frustratingly restrictive, even by the standards of Assembly languages. But you could get much more done with FORTRAN than with Assembler more quickly. I expect one could’ve called the NAG routines from Assembler – but that would’ve been even more work.

So, I think FORTRAN gets a lot of stick. But it’s reasonable to suppose that all the other more elegant languages depended on the pioneer step that was FORTRAN.

Now, does anyone remember using FORTRAN (or even Assembler) on the 3090 Vector Facility? I think maybe 1 or 2 IBM customers in the UK did – but they weren’t in my “social circle” of customers I called on. The legacy today of the Vector Facility is a very large number of reserved opcodes, though I suspect we’re starting to use those now for other things. Does anyone know?

(Originally posted 2007-03-18.)

Some time ago a colleague pointed Scratch out to me. It’s a programming environment for children.

When I was a kid I kind of learnt programming from the Elsevier Monographs my Dad had on his bookshelf. He (who’s probably going to read this) gave them to me for safekeeping some time ago. So I count HIM as my first bad influence. 🙂 But he did insist on STRUCTURED programming, so maybe he’s a GOOD influence. 🙂 Maybe he’s mellowed enough by now to just wait for me to get structured programming for myself. 🙂

Later on we had a Research Machines 380Z at school so I learned more by hands on. Only BASIC and a little Z80 Machine Code.

Then I got a job for 6 months as a professional programmer – before University.

A large part of my Master’s degree was also Computer Science. So I’m proper. 🙂

I won’t bore you with the rest. Suffice it to say I learned to program with a text editor on each platform – and a lot of trial and error and reading manuals, stealing examples, etc. It was an essentially TEXT experience.

So Immi, who’s 8.75, is starting with visual programming. It’s a great way to start. I think it’s much less intimidating than using a text editor. And Scratch is a lot of fun for kids. It allows you to create animations using graphical “characters”, sounds, loops, timers and tests. It’s very much in the drag and drop mode – with the programmer changing parameters in the (jigsaw-like) pieces. It’s rather colourful as well. There’s a thriving ecosystem – with a web site and lots of user-contributed example programs.

So, finally, I asked Immi what she thought of Scratch.

Immi says “Scratch is a good way to teach children how to program and it also teaches them animations don’t just come out of nowhere. :-)”

So there you have it – from a dad’s perspective and a daughter’s.

(Originally posted 2007-03-18.)

Here’s an interesting BBC News Article: Vehicle warning system trialled.

So let me see now, when we said the fridge would talk to the microwave – as everything would have an IP address – did we really envisage that they would Twitter? 🙂 Can you imagine “The Bloggings of an uncleaned fridge?” 🙂

And can you imagine what’d happen if my fridge started Twittering and next door’s microwave yakked back? 🙂

Seriously, I do like the “wisdom of crowds” element of cars talking to one another to relay traffic conditions. But I don’t like the idea (rather like programmed selling) that cars could all decide to take the same diversion? Or that one car could try to sucker the others into getting off its road.

So it might not just be humans that get smart enough to do this stuff.

And the reason I pick up on this peer-to-peer non-human stuff is because we’re used to central authority on things like weather, travel, road conditions… At least in 2 out of those 3 cars already pick up this information centrally. It’s a shift when it becomes peer-to-peer. Kinda like the shift from Web 1.0 to Web 2.0.

(Originally posted 2007-03-17.)

Here’s a useful contribution to the debate about Twitter: From a friend’s blog. There’s much mileage in the comments – which is where the action really hots up. 🙂

Actually her blog is in general a good read – but maybe I’m biased as she’s a friend of mine. She’s a Web 2.0 enthusiast with a great line in photos and original art. (If you want a business justification for reading her blog she’s a manager with IBM’s Rational division.)

(Originally posted 2007-03-16.)

Twice the “128GB” question has come up in newsgroups (the latest in DB2-L). This sort of thing freaks people out – so let me tell you what I know of the matter…

I was fortunate to attend the T3 for DB2 9 in February. This question came up in the context of some changes to DDF:

In Version 8 communication between DDF’s DIST address space and the DBM1 address space was via CSA (actually ECSA so above the 16MB line) and the Private Area. This had two major impacts:

• The CPU cost of moving data between the two address spaces (and I’m told there’s some reformatting, which adds to the cost).
• In extreme cases – large networks of heavy threads – chewing up of scarce ECSA and the DIST private area. (Thread “anchors” reside in the DIST address space and can become large, especially with the new, larger, communications buffer capability.)

So, in DB2 9, the interface between DDF and DBM1 was radically redesigned: Now the communication is done using a z/0S 64-bit Large Memory Object. This is in Virtual Storage above the 31-bit bar. When the DBM1 address space starts up this Large Memory Object is allocated with a 128GB size. Communications take place between DDF and DBM1 using this area: But we’re not talking about data moves and reformatting anymore. So this should cut the CPU. (And it also removes the constraints I mentioned above.)

There are two key points here:

• This is Virtual and not necessarily Real memory.
• The 128GB object is not populated at creation time. So in all case (at least for now) 🙂 the Virtual usage is going to be an order of magnitude or two less than 128GB.

Virtual does drive Real usage, of course. But in this case the increase in Real memory requirement (and there’s bound to be some) is nothing like 128GB.

I should also point out there will be some Virtual storage savings – below the 2GB bar. That will be welcome to a number of customers I know. (And I may well blog about this soon.) But one caution:

I do not expect the need to manage thread numbers and thread footprints to go away, perhaps ever…

DB2 9 does not move the whole thread footprint above the bar. And threads still cost Real memory – though it would take many thousands to have an impact on memory capacity planning. You do do memory capacity planning, don’t you?

(Originally posted 2007-03-14.)

On Twitter I once followed Steve Wozniak – but it turned out not to be him. 😦

Now I’m following John Edwards (and it really does appear to be him). See his Twitter page. I say “it does appear to be him” because the twitterings seem to support that conclusion, plus there is a photograph of him (not that that’s strong evidence). (The ones for the supposed Steve Wozniak never gave credence – it was just a name.) I also see someone claiming to be Barack Obama though this time there are no twitterings (and no photograph).

So there are two issues that come out of it:

• How do you authenticate a voice when it claims to be someone – especially someone famous? And couldn’t someone sign up claiming to be eg Hillary Clinton and then post stuff damaging to her campaign?
• Is this cheap-to-mount personal campaigning style going to change campaigning?

The precedent for all this is the famous person’s blog. I follow but one of these, BTW: Brian May’s. (And he’s only just conceded that his “soapbox” is indeed a blog.) 🙂 But this is a little different as Twitter is much lighter weight: It’s easy to throw out a one-liner in Twitter. It’s rather harder to do that with a blog: People expect more of you.

(Originally posted 2007-02-24.)

I’m writing this in the back of a taxi – on my way to Heathrow. (A 3G card for my Thinkpad was waiting for me when I got home yesterday.)

My conclusion is that we live somewhere “sufficiently rural” as I’ve lost signal once. (That was between us and Henley.) Any more than that and I’d think we lived in the sticks. As it is to actually lose the signal at all is a reassurance that we don’t live anywhere urban(e). 🙂

And, no, I wouldn’t really mind if this “test drive” utterly failed: I only really need the card in places where the likelihood of a signal is strong anyway – such as airports and on trains.

(Originally posted 2007-02-23.)

Whichever it is, here’s my Twitter badge. Feel free to befriend. 🙂