GNU/Hurd
Have you ever considered the GNU/Hurd for SGI? It has some good points:
1) It is designed to be 100% reentrant from scratch and is also heavily multithreaded.
2) Basic kernel is minuscule.
3) Added functionality (files, memory, authorization, scheduling, etc) comes from "servers" which can be replaced at will or even have different ones running at the same time. The point is you can easily have a mix of proprietary/freeware/own-design for different functionalities. Different tasks with conflicting interests could run against different servers and, above all, totally ignore unused servers.
4) According to the developers it is extremely stable, errors never resulting in anything worse than an interruptible hang.
A possible minus is the message-passing between the servers which might be time-consuming.
Still, my feeling is that this could be a real winner on flexibility and performance. Any comments?
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/Torbjörn
This message is a personal message from Torbjörn Gannholm and does not necessarily represent the opinion of my employer.
Quoted 2 lines
A possible minus is the message-passing between the servers which might be time-consuming.
"Yesterdays technology, next week" to quote an OSI saying
Quoted 2 lines
Still, my feeling is that this could be a real winner on flexibility and performance. Any comments?
If you want a pre-emptible OS core its not HURD. Being pre-emptible without deadlocks or other interesting suprises is a very very hard problem. Consider things like disk sorting algorithms when you have 40 blocks for a low pri process queued up with 2 for a real time one.
Quoted 4 lines · Alan Cox
Quoted 2 lines
A possible minus is the message-passing between the servers which might be time-consuming.
"Yesterdays technology, next week" to quote an OSI saying
Possibly, but maybe Unix and Linux also are yesterdays technology in some sense, but cooperative development is the future (and a small bit of the present) and I think it's sad that science is held back because of money and prestige (Although, mind you, I don't mind paying for software and giving credit where it's due, but I want to know what it does and be able to change it if I think I can do something better).
Quoted 9 lines
Quoted 4 lines
Still, my feeling is that this could be a real winner on flexibility and performance. Any comments?
If you want a pre-emptible OS core its not HURD. Being pre-emptible without deadlocks or other interesting suprises is a very very hard problem. Consider things like disk sorting algorithms when you have 40 blocks for a low pri process queued up with 2 for a real time one.
Actually, for the most part I couldn't care less about preemptible or
real-time. I just want to get maximum cream out of my system (scaled to a zillion cpus), and I want it to run until I kill it. Maybe I'm being boring, but to watch video I use a TV, to listen to music I use a HiFi, reality is a lot more interesting than virtual, and to run a nuclear power station I have dedicated machines. And if I did want to use my computer for any of this I could probably load the appropriate mechanisms if they existed and everything else is nicely designed.
IMHO, maybe preemptibility is a fix rather than a solution and the solution lies in another dimension.
But still, why wouldn't some implementation of HURD (or mach) be able to be preemptible?
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/Torbjörn
This message is a personal message from Torbjörn Gannholm and does not necessarily represent the opinion of my employer.
Quoted 2 lines
But still, why wouldn't some implementation of HURD (or mach) be able to be preemptible?
I believe its been done for MACH so that MACH tasks are hard real time. FOr hard real time on Linux Rtlinux sits under the kernel and runs as a very compact realtime microkernel
Got some numbers to go with that?
ron
Ron Minnich |"Using Windows NT, which is known to have some [email protected] | failure modes, on a warship is similar to hoping (609)-734-3120 | that luck will be in our favor"- A. Digiorgio
ftp://ftp.sarnoff.com/pub/mnfs/www/docs/cluster.html
Quoted 3 lines · Ron G. Minnich
Got some numbers to go with that?
ron
Sorry, no. I've only read about what the design ambition is.
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/Torbjörn
This message is a personal message from Torbjörn Gannholm and does not necessarily represent the opinion of my employer.