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Operating Systems

Submission + - Experimental OS' for Evil Geniuses (arizona.edu)

jd writes: "There are now a vast range of experimental Open Source OS' of one kind or another. This is a very quick run-through of a few such OS' that might offer ideas or insights that could lead to improvements in Linux and/or the *BSDs. One of the problems with software development is that research is time-consuming, people-consuming, money-consuming and nerve-consuming. The reason you mostly see tried-and-true ideas being added in gradually, rather than really revolutionary stuff, is that revolutionary programmers are thin on the ground, and that revolutionary implementations are often too specific to be put into a general-purpose kernel if you want to keep the bloat down. The solution? Examine the revolutionary implementations of ideas by others, learn, then steal. Ooops, that should be "paraphrase".

First off, Scout is a networked/distributed OS for embedded devices. The first part is probably done better in Plan 9/Inferno, and the latter is probably done better in specialized embedded OS', especially as Scout is abandonware, but the sheer difficulty of combining these ideas in a space that could fit into a digital camera back when Scout was being developed means this actually has some rather ingenious ideas that are worth revisiting. Besides, for all the good ideas in Plan 9/Inferno, it's not an OS design anyone has exactly picked up and run with, and if Inferno hasn't been abandoned, it's as good as, so offers no advantages in that regard.

Barrelfish is perhaps the most recent and seems to allow you to build a highly-scalable high-performance heterogeneous cluster, for example, though I'm suspicious of Microsoft's involvement. Oh, I can believe they want to fund research that they can use to make their own OS' run faster, after all the complaints over Vista, but they're not exactly known for supporting non-Intel architectures. On the other hand, ETH Zurich are very respectable and I could see them coming up with some neat code. Anyways, the idea of having a cluster that can work over multiple architectures (ie: not a SSI-based cluster) is potentially very interesting.

But they're not the only guys doing interesting work. K42 (with HHGTTG references in the docs) is supposed to be a highly scalable, highly fault-tolerent OS from IBM, who quite definitely have an interest in doing precisely that kind of work. Given IBM is currently selling Linux on its HPC machines, it would be reasonable to suppose the K42 research is somehow related, perhaps with interesting ideas working their way into the Linux group. And if that isn't happenening, it damn well should, as directly as licenses and architecture permit.

The L4 microkernel group has been around for a long time now. Although microkernels have their issues, running modules in userspace has advantages for security and communicating via messages would (in principle) allow those kernel modules and kernel threads to migrate between cluster nodes — a major headache that Linux-based clusters (such as OpenMOSIX) have a very hard time solving.

One Open Source microkernel that does exactly that is Amoeba, though it has become abandonware. It's a truly amazing piece of engineering for distributed computing that is slowly becoming an amazing piece of dead code through bitrot. However, if you want to set out to compete with Kerrighed or MOSIX, this might be a good place to look for inspiration.

Then there's C5. Fortunately, not the one invented by Sir Clive Sinclair, but rather a rather intriguing "high-availability carrier-grade" microkernel. Jaluna is the Open Source OS toolkit that includes the C5 microkernel. Now, many are the boasts of "carrier-grade", but few are the systems that merit such a description. The term is usually taken to mean that the OS has 5N reliability (ie: it will be up 99.999% of the time). One of the problems in this case, though, is that if it requires additional layers to be useful, 5N reliability in the microkernel doesn't mean anything useful. You could build an OS that only supported /dev/null as a device, and do so with far far greater reliability than 5 nines, but so what? Nonetheless, there may be things in C5 that are worth looking at.

Calypso is a "metacomputing OS", which seems to be the latest buzzword-compliant neologism to describe a pile-of-PCs cluster. On the other hand, abstract and efficient parallel systems mean better utilization of SMP and multicore systems and therefore better servers and clients for MMORGs.

I think most Slashdotters will be familiar with FreeRTOS — an Open-Source version of a very popular real-time OS. This OS is being used by some members of the Portland State University's rocketry group as it is absolutely tiny and will actually fit on embedded computers small enough to shove into an amateur rocket. There's a commercial version that has "extra features". I don't like — or trust — companies that do this, as altering the number of pathways in code will alter the quality of the code that is left. Unless it's independently verified and QA'd (doubtful given the approach being followed), it is not safe to assume that because the full source is good that a cut-down version won't be destabilized. On the other hand, if you want a simple embedded computational device (for your killer robot army or whatever), FreeRTOS looks sufficiently general-purpose and sufficiently hard real-time.

There are, of course, plenty of other OS' — some closed-source (such as ThreadX) and some open-source (such as MINIX 3) which have some — indeed, sometimes many — points of interest. However, there's not much point in listing every OS out there (Slashdot would run out of space, I'd get tired of typing, and I'd rapidly run out of put-downs). Besides which, at the present time, the biggest problem people are trying to solve are multi-tasking on SMP and/or multi-core architectures and/or clusters, grids and clouds. Parallel systems are bloody difficult. The second problem is how to provide the option of having fixed-sized time-slices out of a fixed time interval — often for things like multimedia. This is not the same as "low latency". It's not even deterministic latency, except on average. (It's only deterministic if not only does a program have a guaranteed amount of runtime over a given time interval, but it ALSO has a guaranteed start-time within that interval.) What RTOS' normally provide is deterministic runtime and a guarantee that the latency cannot exceed some upper limit. From the number of times the scheduler in Linux has been replaced, it should be obvious to all-and-sundry that providing any kind of guarantee is extremely hard and — as with the O(1) scheduler — even when the guarantee is actually met, you've no guarantee it'll turn out to be the guarantee you want.

A third problem people have tried to tackle is reliability. There's a version of LynxOS (a Linux variant, I believe) which is FAA-approved for certain tasks (it has the lowest certification possible). There was, at one point at least, also a carrier-grade Linux distro, but I've not seen that mentioned for a while. If you include security as a facet of reliability, then there are also Linux distros that have achieved EAL4+ ratings, possibly EAL5+. Some of the requirements in these projects is mutually-exclusive, which is a problem, and clearly the way the requirements were implemented are or we'd be seeing projects evolving FROM these points rather than the projects being almost evolutionary dead-ends.

It would seem logical, then, to go back to the experimental kernels where the fringes of OS theory are being developed, dyed and permed. Study what people think might work, rather than the stuff that's already mainstream or already dead, see if there's a way to use what's being discovered to unify currently disparate projects, and see if that unification can become mainstream. Even if it can't, not having to re-invent everything is bound to speed up work on the areas that are least-understood and therefore in most need of work."

Comment Re:Capital Punishment (Score 1) 328

If you kept all the violent and really evil, sick, twisted people locked up, who would we have for lawyers? Politicians? Accountants? CEOs?!

The Huge Manatee!

Please, please, think of the scumbags!

(Seriously, I don't have any objection to people who need to be locked up being locked up. I do have an objection to that being the sole purpose of the legal system - people can change and it's fair to give them the means and opportunity even if they stay incarcerated. It also seems reasonable to give those who will be released the motive to try an alternative. Punishment alone never works and resentment is a great way to encourage people to think of other ways of being crappy to others.)

Comment Personally... (Score 4, Insightful) 328

I regard the death penalty as somewhat childish and immature. "If X can't be alive, then... then... Neither Can Yoooooo! So nyah!" The idea that it gives closure to anything seemed to get a kick in the nuts with the Beltway Sniper's execution. If you don't get closure when the other person doesn't cry, then I'm not sure it's "closure" you're looking for. Try looking up "schoolyard bully".

I'm also not keen on the way a lot of these trials are handled, especially the insanity stuff. A person being insane doesn't alter whether or not they did something, it merely alters their culpability. That should be obvious.

Ergo, it follows that insanity should not be a plea in the trial phase but confined strictly to that phase which deals with culpability, the sentencing.

However, I also disagree with this idea that there are two options - total all-out criminal insanity and total all-out sanity. For a start, it doesn't leave you with anywhere to put lawyers or politicians.

I would far prefer to see a system in which sanity is regarded as a sliding scale and where sentencing allows the judge to split the time between punishment, treatment and rehabilitation (as and where appropriate) according to what produces the best outcome overall, rather than according to what gives the weenies in the press box a vicarious thrill.

Obviously, if a person is going to be incarcerated forever, then rehabilitation to the point where the person would be safe outside is not terribly useful. On the other hand, it seems reasonable to assume that having them stew, rebel and resent is both less cost-effective and less mature than encouraging them to make effective use of their abilities.

Just because someone is sealed off from society doesn't mean society can't benefit from their mind - there's probably plenty of intellectuals and artists behind bars.

Ian Brady is probably one of the craziest crazies to be in Broadmoor, but his book on the way serial killers think, feel and act should certainly be at least browsed by psychiatrists and detectives for insights no rational mind could ever have produced. No matter how little value it really is, the chances are really good that it'll do more good than the British Police's DNA database and CCTV camera system.

I'd rather let a hundred cold-blooded killers live in jail and receive at least some respect as a person if it meant that just one of those hundred produced a masterpiece of art or a book that had significance than have all hundred die purely for the viewing pleasure of Weekend Warriors.

In a hundred years time, which makes the difference? Something that might only rarely advance humanity - but when it does, advance it a lot - or something that provides a momentary mental orgasm for a bunch of f'ed-up "witnesses" and some losers outside and that's it?

I don't see why I should pay taxes for someone getting off on watching another die, when I could be paying taxes to give those in prison a chance to do something positive and worthwhile.

Comment Re:Wrist Watches are Useful (Score 1) 778

Weren't casio watches considered evidence of involvement in terrorism in Afghanistan? And yours works off nuclear stuff, too! Definitely dodgy.

(On the other hand, that is one seriously cool watch. Probably not one I could afford right now, but with sales of anything being so bad this year, you never know.)

Comment Re:Rediscovering obsolescence (Score 1) 778

Out-nerded you, then. It was temporarily repaired in Logopolis, although the TARDIS only actually changed shape in one story quite a bit later than that and never changed again.

Come to think of it, it was invisible in The Invasion and therefore might have been any shape at all prior to rematerializing as a police box at the very end.

The Sensorites were able to remove the locking mechanism, resulting in a change to the outward appearance. Thus, even then, the chameleon circuit wasn't so stuck that it couldn't adjust the shape accordingly.

For that matter, although The Doctor has claimed the TARDIS can't change shape, it has not retained the same police box exterior, showing that some chameleon capability exists.

My personal suspicion is that the First Doctor forgot how to change the shape and that later Doctors kept the basic design as a cross between a trademark and a banner.

Comment Re:No P&S camera (Score 1) 778

Heh. First, I'm increasingly skeptical of New Scientist. It went downhill after scrapping the Arianne column. Second, computers can't generate accurate information that isn't there, although they CAN synthesize data values that would be valid based on known information.

Using sound as an example, since you know the general shape of a sine wave, it is perfectly valid to non-linearly interpolate a digital recording to produce an analog waveform that would have produced an identical digital recording. What you cannot do is know if this was the actual original waveform.

If you're really clever, you may even be able to spot relationships between different components of the digital recording. For example, you know that any waveform can be split into simpler waveforms (fourier analysis) and you know that some component waves should relate to specific other component waves (many natural sounds will have harmonics, there may be echoes, and so on). This might allow you to identify some reconstructions as more probable than others. There may be other characteristics and meta-information you can use to refine the process further.

Now, I'll grant the possibility of some very, very good reconstructions from a good image. I'll even grant that a sophisticated enough camera may be able to capture meta-data that could be used to produce a brilliant reconstruction.

What I can't possibly accept, though, is a good reconstruction from a lossy capture at low dynamic range and low resolution and an even lossier image compression into JPEG or other lossy image format. Passable, perhaps, but not good.

Now, if someone could build a camera for a phone that could store images in OpenEXR, -and- have the sensor good enough that using an HDR format made sense, -and- have enough memory on the phone that you could store an image of a few megapixels res, THEN I could accept just about any reconstruction claim the inventor cared to make for the images. Mind you, why would you need to reconstruct anything if the camera is doing all that already?!

Comment Re:No P&S camera (Score 1) 778

If all you measure is the impact of a photon of a very specific energy, the event happens or it doesn't. There's not a whole lot of alternative states.

And, no, there aren't going to be a whole lot of analog effects that interfere with the light-sensitive component. You can't have half an electron jump (it's quantized) and you can't have a fraction of a count (it increments by one or it doesn't). Photon counters are remarkably reliable and very accurate. They're also horribly slow (you accumulate state over a long time) which makes them brilliant for astronomy but useless for even still pictures if the scene has any moving component.

Analog effects WILL affect the analog component, but as I clearly differentiate, you're being an idiot if you confuse the two.

Hard radiation can always mangle solid-state circuits, sure, but I wasn't really considering those to be a typical scenario.

Thermal problems really won't affect a photon counter, as that just alters the movement of atoms. If the camera is exposed to enough heat that the electrons migrate, and it's a point-and-shoot (which basically means plastic lens and cardboard or plastic case), the camera is going to have more problems than a spurious value.

(Remember, we are talking point-and-shoot vs camera phone here, not the Hubble Telescope.)

Reference voltages won't affect the count, because you don't use any. Reference voltages will affect the analog circuits, though, but again those are considered separately.

Quantum effects shouldn't be a problem, since you are not measuring anything (you are only counting) and a pixel isn't on the same order of magnitude as the wavelength.

Remind me, is there anything I'm missing on the list?

Comment Re:No P&S camera (Score 1) 778

Now THAT is a valid argument. If the phone camera does everything you want and need for your general use, then it doesn't matter if a PAS camera is better in any technical sense. I'm still not convinced you really get 5MP, even if the box says you do, but if it gives the results you want then who really cares?

Comment Re:No P&S camera (Score 1) 778

Even DACs are digital devices that produce analog signals, but ANY device based on the photoelectronic effect at a fixed frequency is a digital device (it's either on or off). The analog signal generated is dependent on how many photons are collected in a given interval of time.

God, has Slashdot descended to such depths in only a few decades that people haven't looked up the alternatives to CCDs?

Comment Re:Neo-luddite (Score 2, Funny) 778

I am, and I'll accept that you are, but the vast majority of people have a really suspect intellectual capacity, a very shaky grasp on reality (I hear some people even believe politicians, accountants and/or Scientologists) and an attention-span of a 3 year old. On a good day.

When you consider that Oprah Winfrey is considered to be the height of intellectualism on US television and Coast-to-Coast AM has more credible stories than many of the popular news outlets, it's clear that the species has some serious shortcomings.

On the other hand, Neolithic people had perfectly functional and valuable neurosurgeons, had tools with better-than-millimetre precision, were capable of large-scale transatlantic sea voyages and were building some very good echo chambers.

So when you compare modern humanity (by which you realize you're including Palin supporters, rednecks, New York taxi drivers, Frank Bruno, Hulk Hogan and Terry Wogan) with Neolithic and Paleolithic people, I'm really not convinced humans are advanced as you think.

Comment Re:Wrist Watches are Useful (Score 1) 778

A decent analog watch has superbly-crafted components and therefore deserves the admiration. A decent digital watch needs something marginally better than a 555 timer, but only marginally.

That's not to say I wouldn't gave respect for a digital watch with the accuracy and drift of a scientific high-precision timer. I'd consider it adequately impressive for a digital watch to have a drift of a few nanoseconds a day.

(I'm judging analog differently than digital in the resolution, but really about the same in terms of the effort required to produce a system of a given standard because that's the only measure of craftsmanship you can ever really have.)

Comment Re:!begsthequestion (Score 1) 778

Maybe it's the Asperger's in me, but after getting years of verbal grief for being different, I have no problem with neurotypicals begging. Actually, I don't think that is the Asperger's. I think I might just have become more cynical and more anti-social in my old age. (And gerroff the lawn!)

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