musing

RSH and RLogin aren't that difficult to set up once you've gone through the man pages and done the installation a few times, but those first few times are a pain. They're old and insecure, but still frequently used on small compute clusters. I get the impression that a lot of beginners get stuck fiddling with them for hours or days. They're quite possibly the biggest stumbling block one faces when setting up a compute cluster by hand (setting /etc/hosts.equiv, setting /root/.rhosts, making sure the right flags are being sent to the rsh and rlogin daemons, etc).

Both use the xinetd daemon, which is one of those carry-overs from ancient Unix. Plenty of old Unix stuff made sense, but inetd is backwards. To enable a service, you set "disabled = no". To disable a service, you set "disabled = yes".

Putting double negatives in your configuration file is not a good idea. When a setting this basic takes a couple seconds of thought, you're doing it wrong. Were it something more complicated, administrators would be selecting the wrong option all the time.

Parents frequently need to discuss issues, but their kids rarely give them the opportunity to do so. Speaking freely is usually counterproductive, because you're often talking about the kids (e.g. they'll flip out if they find out you're discussing whether they can have candy). But today I realized we've stumbled upon a method which actually helps the kids a lot.

Currently, we alternate between speaking Spanish and using large words (at least 3 or 4 syllables). It's obviously beneficial for them to be exposed to multiple languages. And using large words not only gives my own vocabulary a workout, it's great for the kids. After a few uses, our 3 year old is randomly using 4-syllable words in sentences. Now I'll have to dig deeper for harder words, and he'll pick those up too! There isn't anything much cuter than hearing a 3 year old trying to say "complicated" or "detonation".

I've been dabbling with computer game design for half a decade (I had crazy dreams about making games way before that, but didn't write code back then). It's been strictly a part-time hobby, but for the amount of time I've spent I don't have much visual evidence of my work.

Compared to coders who churn out games in a couple weeks, it's fairly embarrassing. This seems to be a common joke among game creators, as everyone on the net claims to have the "best" idea for their game and none are ever produced. I'd bet most game ideas don't even turn into a single line of code, and those that do are soon abandoned. I'm trying to rationalize how this doesn't apply to me...   read more >>

When working on high performance supercomputers, network latency and bandwidth are of utmost importance. If messages cannot be sent quickly enough between compute nodes, a supercomputer may actually perform more poorly than a standard server or workstation. So much time is spent waiting for input from other locations that nothing is actually accomplished. These days, more time is spent optimizing latency than bandwidth since most clusters have all the bandwidth they need (2-4GB/sec).

I've discovered that an analogy can be made with traffic on the highway. Computers keep getting faster, and now maybe traffic can too. I promise you'll notice this the next time you head out on the road.   read more >>

I definitely behave like a pack-rat on occasion. Particularly when it comes to digital content, which is painless to store and relatively easy to organize, there is a great temptation to keep everything. But at the same time, I recognize that our brain's capability to forget is actually beneficial - unimportant/unimpressive things shouldn't take up space or waste our time.

I seriously suspect this will come back to haunt a lot of us in the future, as we accumulate unprecedented quantities of digital goods we can't bear to let go of. Imagine having to wade through 100,000 photos your parents took during the course of their lives. Would you ever bother to do it? How many would you actually care to keep? What if each branch on your family tree had that many photos?

In that spirit, I am revisiting the content of my site. The good and useful will stay - all else will fade...