From: Enno Luebbers <enno.luebbers@uni-paderborn.de>
To: ecos-discuss@ecos.sourceware.org
Subject: Re: [ECOS] Hard-Realtime behaviour
Date: Tue, 30 May 2006 14:44:00 -0000 [thread overview]
Message-ID: <F0E08477-6DB3-4B97-A88D-DE29A410CB71@uni-paderborn.de> (raw)
In-Reply-To: <20060530111436.GL2876@lunn.ch>
Hi,
>> @Andrew : As we have seen most of what is necessary for hard realtime
>> behaviour of eCos already is implemented. Can you help me in
>> figuring out
>> what is it that is missing that makes eCos soft real-time.
>
> What is missing? I would say the first step is to make a really good
> definition of what hard realtime is.
I think we can all agree that a real-time system is a deterministic
system, i.e. it is _predictable_ in its timing behaviour. The
distinction between hard and soft real-time, IMO, depends on the
application. In a soft real-time system, some deadline misses can be
tolerated - they only degrade the system's performance or service
quality (think video streaming). On the other hand, a deadline miss
in a hard real-time system causes a (catastrophic) system failure
(think electronic brakes, engine control, etc).
So, if the OS routines in eCos are sufficiently predictable (so you
can for example get upper bounds on the execution time) it's actually
the application (read: the way the application programmer uses eCos
services) that defines whether the system is hard or soft real-time.
Best,
- Enno
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next prev parent reply other threads:[~2006-05-30 14:44 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-29 16:09 R Vamshi Krishna
2006-05-29 16:26 ` Fabian Scheler
2006-05-29 21:16 ` Wolfgang Köbler
2006-05-30 5:13 ` R Vamshi Krishna
2006-05-30 7:53 ` Andrew Lunn
2006-05-30 8:09 ` Fabian Scheler
2006-05-30 8:16 ` Andrew Lunn
2006-05-30 9:25 ` R Vamshi Krishna
2006-05-30 11:12 ` Andrew Lunn
[not found] ` <"Pine.LNX.4.61 .0 606031953120.6382"@mars.cse.iitb.ac.in>
[not found] ` <Pine.LNX.4.61.0606040253350.26447@m ars.cse.iitb.ac.in>
[not found] ` <Pine.LNX.4.61.0 606031953120.6382@mars.cse.iitb.ac.in>
[not found] ` <Pine.LNX.4.61.0 606031953120.6382@mars.cse.iitb.ac.in>
2006-06-03 16:26 ` R Vamshi Krishna
2006-06-03 20:13 ` Roy E Richardson
2006-06-03 21:31 ` R Vamshi Krishna
[not found] ` <003401c6885d $23027ee0$070fe644@EngAtPlayWS>
[not found] ` <003401c6885d $23027ee0$070fe644@EngAtPlayWS>
[not found] ` <003401c6885d$23027ee0$070fe644@EngAtPlayWS>
2006-06-18 22:21 ` R Vamshi Krishna
2006-06-18 23:31 ` John Carter
2006-06-18 23:46 ` R Vamshi Krishna
2006-06-19 0:27 ` John Carter
2006-05-30 11:15 ` Andrew Lunn
2006-05-30 14:44 ` Enno Luebbers [this message]
2006-05-30 9:34 ` Nils Labugt
2006-05-30 10:37 ` Fabian Scheler
2006-05-30 11:21 ` Luis Friedrich
2006-05-30 11:47 ` Fabian Scheler
2006-05-30 12:48 ` R Vamshi Krishna
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