LCA: Andrew Tanenbaum on creating reliable systems

Posted Jan 18, 2007 13:41 UTC (Thu) by RobSeace (subscriber, #4435) [Link]

I've written commercial code running under versions of QNX from 2.x to 4.x
for many, many years now, and let me tell you: it doesn't even come close to
living up to its hype... Speed? Sure, local IPC via Send()/Receive()/Reply()
is nice and quick, and the same remotely isn't bad, either... But, that's
about the only thing it's got going for it, speedwise... Compare normal
real-world-used standard IPC interfaces, such as pipes or TCP/IP, and the
situation changes dramatically, because they're all welded on almost as an
afterthought, and built on top of that fast SRR messaging, but adding more
layers to go through (and often multiple user-space processes that need to
be communicated with in order to get things done), rather than being first-class
interfaces in their own right... And, reliability? I've seen FAR more
examples of QNX crashing in various unpleasant ways than I ever have seen
from Linux (or pretty much anything outside of a Microsoft OS)... Sure,
most stuff is just a user-space app; but, if your "Dev" app or your "Fsys"
app goes away, you end up pretty well screwed, just as badly as if it were
part of the kernel itself...

QNX has lots of nifty features, and it's great for some specific uses...
For embedded systems, it's probably perfect... But, for a normal server or
desktop/workstation computer for normal everyday use, it's absolutely horrible,
and Linux has it outclassed by miles in every possible area I can think of...
This coming from someone whose main workstation ran QNX 4.x for many years,
so I'm not just making stuff up... When I switched my main dev environment
to Linux, it was absolute nirvana in comparison... Maybe it's because I
come from a Unix background, and QNX is just enough like Unix to make you
frustrated at all the ways it's NOT like Unix... But, whatever it is, I
find myself a LOT happier programming under Linux, that's for sure... (And,
when Linux differs from standard Unix stuff, it's usually in a much more
pleasant and superior way, rather than a frustratingly annoying way... ;-))

(And, note: I have no experience with the newest incarnations of QNX;
"Neutrino", or whatever it is they're calling it these days... 4.2x was the
last version I ever dealt with... So, maybe all my complaints are baseless
these days... *shrug* I've heard they've moved to gcc instead of that lousy
Watcom compiler, so that'd be ONE major improvement right there...)