* TRON for AdaOS
@ 2005-02-17 7:31 Marius Amado Alves
2005-02-17 12:50 ` Marin David Condic
0 siblings, 1 reply; 8+ messages in thread
From: Marius Amado Alves @ 2005-02-17 7:31 UTC (permalink / raw)
To: comp.lang.ada
Nick Roberts, David Botton, and all:
Have you considered the TRON Specifications for AdaOS?
Just an idea that may or may not speed up AdaOS construction, and at
the same time tap into a somewhat different but striving (at least in
Japan) market.
The TRON Specifications are a set of open specifications of real-time
operating systems. Initially developed at Sakamura Labs I think.
Personal Media Corp. (also Japanese) now offers the T-Engine Kit at
circa 1500 euros. The T-Engine Kit is a TRON-based combination of
hardware and software for system development.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: TRON for AdaOS
2005-02-17 7:31 TRON for AdaOS Marius Amado Alves
@ 2005-02-17 12:50 ` Marin David Condic
2005-02-17 13:37 ` Marius Amado Alves
0 siblings, 1 reply; 8+ messages in thread
From: Marin David Condic @ 2005-02-17 12:50 UTC (permalink / raw)
Would you happen to have any links or textbook references?
I like the idea of an Ada RTOS - although others have been built. (Might
be better to start from something like RTEMS & build on it?) There are
also various realtime Linux implementations one might learn from. At
least one implementation I have heard of runs a single realtime process
and then coughs up any leftover CPU time to run the rest of Linux. I
hear it works pretty well and provides a basis for an OS that does
something Windows doesn't do. You've got to think of why anyone would
want an Ada OS besides the fact that it is implemented in Ada.
MDC
Marius Amado Alves wrote:
> Nick Roberts, David Botton, and all:
>
> Have you considered the TRON Specifications for AdaOS?
>
> Just an idea that may or may not speed up AdaOS construction, and at the
> same time tap into a somewhat different but striving (at least in Japan)
> market.
>
> The TRON Specifications are a set of open specifications of real-time
> operating systems. Initially developed at Sakamura Labs I think.
> Personal Media Corp. (also Japanese) now offers the T-Engine Kit at
> circa 1500 euros. The T-Engine Kit is a TRON-based combination of
> hardware and software for system development.
>
--
======================================================================
Marin David Condic
I work for: http://www.belcan.com/
My project is: http://www.jsf.mil/NSFrames.htm
Send Replies To: m o d c @ a m o g
c n i c . r
"'Shut up,' he explained."
-- Ring Lardner
======================================================================
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: TRON for AdaOS
2005-02-17 12:50 ` Marin David Condic
@ 2005-02-17 13:37 ` Marius Amado Alves
2005-02-17 14:37 ` Ole-Hjalmar Kristensen
0 siblings, 1 reply; 8+ messages in thread
From: Marius Amado Alves @ 2005-02-17 13:37 UTC (permalink / raw)
To: Marin David Condic; +Cc: comp.lang.ada
Primary TRON sites (in my understanding):
http://www.tron.org
http://www.sakamura-lab.org
http://www.personal-media.co.jp
If your Japanese is, like mine, a bit rusty :-) check these items:
http://tronweb.super-nova.co.jp
http://www.linuxinsider.com/story/31855.html
Regarding real-time power and RTLinux, this excerpt from the latter
item deserves spotlighting:
"RTLinux switches tasks in milliseconds, while ITRON switches tasks in
microseconds," he said. "RTLinux' footprint is measured in megabytes;
ITRON is measured in kilobytes."
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: TRON for AdaOS
2005-02-17 13:37 ` Marius Amado Alves
@ 2005-02-17 14:37 ` Ole-Hjalmar Kristensen
2005-02-17 14:55 ` Vinzent 'Gadget' Hoefler
2005-02-18 13:20 ` Marin David Condic
0 siblings, 2 replies; 8+ messages in thread
From: Ole-Hjalmar Kristensen @ 2005-02-17 14:37 UTC (permalink / raw)
>>>>> "MAA" == Marius Amado Alves <amado.alves@netcabo.pt> writes:
MAA> Primary TRON sites (in my understanding):
MAA> http://www.tron.org
MAA> http://www.sakamura-lab.org
MAA> http://www.personal-media.co.jp
MAA> If your Japanese is, like mine, a bit rusty :-) check these items:
MAA> http://tronweb.super-nova.co.jp
MAA> http://www.linuxinsider.com/story/31855.html
MAA> Regarding real-time power and RTLinux, this excerpt from the latter
MAA> item deserves spotlighting:
MAA> "RTLinux switches tasks in milliseconds, while ITRON switches tasks in
MAA> microseconds," he said. "RTLinux' footprint is measured in megabytes;
MAA> ITRON is measured in kilobytes."
I would be very surprised if "RTLinux switches tasks in milliseconds"
actually is true. On my system, (a vanilla Linux admittedly :
2.4.9-e.34smp #1 SMP ), task switching takes about 4.5 microseconds.
--
C++: The power, elegance and simplicity of a hand grenade.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: TRON for AdaOS
2005-02-17 14:37 ` Ole-Hjalmar Kristensen
@ 2005-02-17 14:55 ` Vinzent 'Gadget' Hoefler
2005-02-18 9:13 ` Ole-Hjalmar Kristensen
2005-02-18 13:20 ` Marin David Condic
1 sibling, 1 reply; 8+ messages in thread
From: Vinzent 'Gadget' Hoefler @ 2005-02-17 14:55 UTC (permalink / raw)
Ole-Hjalmar Kristensen wrote:
> I would be very surprised if "RTLinux switches tasks in milliseconds"
> actually is true. On my system, (a vanilla Linux admittedly :
> 2.4.9-e.34smp #1 SMP ), task switching takes about 4.5 microseconds.
And that timing is guaranteed?
Vinzent.
--
worst case: The wrong assumption there actually is one.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: TRON for AdaOS
2005-02-17 14:55 ` Vinzent 'Gadget' Hoefler
@ 2005-02-18 9:13 ` Ole-Hjalmar Kristensen
2005-02-18 9:46 ` Vinzent 'Gadget' Hoefler
0 siblings, 1 reply; 8+ messages in thread
From: Ole-Hjalmar Kristensen @ 2005-02-18 9:13 UTC (permalink / raw)
On my system, it's surely not guaranteed. But it's perfectly adequate
for building soft real time systems.
My point is that the task switching overhead itself is very low on
Linux. I did not say anything about the granularity of the time slice.
My test program also includes the overhead in accessing a shared
protected object, btw.
>>>>> "V'H" == Vinzent 'Gadget' Hoefler <nntp-2005-02@t-domaingrabbing.de> writes:
V'H> Ole-Hjalmar Kristensen wrote:
>> I would be very surprised if "RTLinux switches tasks in milliseconds"
>> actually is true. On my system, (a vanilla Linux admittedly :
>> 2.4.9-e.34smp #1 SMP ), task switching takes about 4.5 microseconds.
V'H> And that timing is guaranteed?
V'H> Vinzent.
V'H> --
V'H> worst case: The wrong assumption there actually is one.
--
C++: The power, elegance and simplicity of a hand grenade.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: TRON for AdaOS
2005-02-18 9:13 ` Ole-Hjalmar Kristensen
@ 2005-02-18 9:46 ` Vinzent 'Gadget' Hoefler
0 siblings, 0 replies; 8+ messages in thread
From: Vinzent 'Gadget' Hoefler @ 2005-02-18 9:46 UTC (permalink / raw)
Ole-Hjalmar Kristensen wrote:
> My point is that the task switching overhead itself is very low on
> Linux.
Yes. But such things can change when you apply real-time requirements.
Sometimes it is very surprising to see the difference between an
average-case optimization and a worst-case optimization. ;-)
Well, I searched for it and the context switching times simply seem to
depend on the method used.
<URI:http://trecom.upv.es/articles/NTCC150-4.PDF> states:
|The communication method between the scheduler and the Linux process
|can be done by means of the RT-Linux standard RT-fifos, although a
|shared memory mechanism has also been implemented in order to improve
|efficiency. This method allows the scheduler to improve context
|switches by three milliseconds below the accomplished with the FIFO
|communication.
So indeed here they talking about milliseconds, but with the shared
memory approach this seems to change considerably:
|Some measurements about context switching times in RT-Linux have been
|made in the execution of the previous program. [...] In the case of
|interrupts, this time is very variable, but it can be up to 20
|microseconds in the worst case. [...] In the case of system calls, the
|context switching time is much lower: 8 µs. The scheduler requires
|about 4 microseconds.
So that doesn't sound too bad. ;)
Vinzent.
--
worst case: The wrong assumption there actually is one.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: TRON for AdaOS
2005-02-17 14:37 ` Ole-Hjalmar Kristensen
2005-02-17 14:55 ` Vinzent 'Gadget' Hoefler
@ 2005-02-18 13:20 ` Marin David Condic
1 sibling, 0 replies; 8+ messages in thread
From: Marin David Condic @ 2005-02-18 13:20 UTC (permalink / raw)
See: http://www.linuxdevices.com/articles/AT8916798258.html
The RTLinux Manifesto seems to suggest performance is pretty good. I
know of it being used in real world hard realtime applications, so it
can't be all that bad. It may not be the best or only answer so Tron may
have something going for it too.
Of course the real problem is that there is no truly active and
progressing effort to build a usable Ada OS, so it all gets kind of
academic as to whether or not RTLinux or Tron or anything else can help
out in some regard.
MDC
Ole-Hjalmar Kristensen wrote:
>
> I would be very surprised if "RTLinux switches tasks in milliseconds"
> actually is true. On my system, (a vanilla Linux admittedly :
> 2.4.9-e.34smp #1 SMP ), task switching takes about 4.5 microseconds.
>
--
======================================================================
Marin David Condic
I work for: http://www.belcan.com/
My project is: http://www.jsf.mil/NSFrames.htm
Send Replies To: m o d c @ a m o g
c n i c . r
"'Shut up,' he explained."
-- Ring Lardner
======================================================================
^ permalink raw reply [flat|nested] 8+ messages in thread
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2005-02-17 7:31 TRON for AdaOS Marius Amado Alves
2005-02-17 12:50 ` Marin David Condic
2005-02-17 13:37 ` Marius Amado Alves
2005-02-17 14:37 ` Ole-Hjalmar Kristensen
2005-02-17 14:55 ` Vinzent 'Gadget' Hoefler
2005-02-18 9:13 ` Ole-Hjalmar Kristensen
2005-02-18 9:46 ` Vinzent 'Gadget' Hoefler
2005-02-18 13:20 ` Marin David Condic
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