Messages in this thread | | | Date | Sun, 20 Jun 1999 21:06:59 +0200 (CEST) | From | Rik van Riel <> | Subject | Re: Some very thought-provoking ideas about OS architecture. |
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On 20 Jun 1999, Linus Torvalds wrote:
> >Unfortunately, EROS is still based on the PC hardware as > >we've got it today and not modeled after a JINI-like > >appliances model (the network is the computer). > > That's a classic thing said by "OS Research People".
Which I'm not :)
> I don't understand people who think that "distribution" implies > "collective". > > A distributed system should be composed of individual stand-alone > systems that can work together.
OK. I can agree with this. Still, Bill Joy can't be alltogether wrong, can he? This is somewhat of a dillemma -- having to choose between the paradigms of Bill Joy and Linus Torvalds... :)
> >(http://www.allos.org/). > > I will tell you anything based on message passing is stupid. It's > very simple: [communications overhead is either in the actual communication channel or unneeded]
The Alliance OS uses something like a shared library so that what looks like message passing from higher levels only is message passing when it needs to be -- otherwise the higher overhead is avoided.
> - Most operations are going to be local.
Optimizing for the local case doesn't mean that remote operations can't be made transparent. Because of latency problems, you are probably right though...
> - Truly mobile computing implies that a noticeable portion of the time > you do _not_ want to be in contact with any other computers. Your > computer had better be a very capable one even on its own.
It depends. If a computer is used as a way of getting at information, then you will want it to be connected. Mobile phones simply aren't very useful on the north pole, however well they might function on their own. Computing is more and more about communication and not about number-crunching or playing games -- which, I agree, can be done very well without network access.
Even for things like a calendar you will want access to outside information. If you plan an appointment with someone else, you need to be able to communicate with eachother to agree on a date/time both of you are able to meet...
> In short: message passing as the fundamental operation of the OS > is just an excercise in computer science masturbation. It may > feel good, but you don't actually get anything DONE.
It can help achieve things we can't do with Linux:
Upgrade (parts of) the OS while running. Since message passing objects are self-contained, you can replace them more easily than possible with 'classic' OSes. User process migration and other nice scalability and/or reliability tricks are also more easily done.
Transparent networking. While userland can do this in a library, this feature can be very useful to achieve high availability because it makes clustering at the filesystem level extremely easy (to name a thing).
Sandboxing parts of the OS. Finally it's possible to test new kernel parts without risking the rest of your system. Debugging a new networking library (kernel-level, that is) without endangering the rest of the system to stray pointers. The sandboxing protection can always be removed later when the new kernel addition has been found to work properly.
While I agree with your point that computers will be both powerful enough to do anything and never powerful enough not to need the maximum level of optimization (this seemed to be what you were saying and, however paradoxical it may seem, will probably be true forever), I think you should take a more positive attitude towards new system concepts.
Even if you don't like them, some very nice and useful spinoffs could come from the research in those areas. We need diversity in order to select the best alternative for the job at hand.
I won't try to convince anyone to turn Linux into such a system. Not only doesn't it make sense, I wouldn't even want Linux if it became like that -- other systems can take on other roles that are to be played in the huge playing field that's out there...
Rik -- Open Source: you deserve to be in control of your data. +-------------------------------------------------------------------+ | Le Reseau netwerksystemen BV: http://www.reseau.nl/ | | Linux Memory Management site: http://www.linux.eu.org/Linux-MM/ | | Nederlandse Linux documentatie: http://www.nl.linux.org/ | +-------------------------------------------------------------------+
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