From: Andrew Lunn <andrew@lunn.ch>
To: Wolfgang K?bler <wk-list@koebler.com>
Cc: ecos-discuss@ecos.sourceware.org
Subject: Re: [ECOS] Hard-Realtime behaviour
Date: Tue, 30 May 2006 07:53:00 -0000 [thread overview]
Message-ID: <20060530075335.GG2876@lunn.ch> (raw)
In-Reply-To: <XFMail.20060529195143.wk-list@koebler.com>
> 8. ...
>
Disable the caches. How long something takes to execute will depend on
what is in the cache. If the code to be executed is still in the cache
from the last time it was executied, it will execute a lot quicker
than if it has to be fetches from RAM/ROM. The same applies to the
data to be processed. So to be deterministic, you need to disable
caches.
It was much easier to write hard real time systems on older
hardware. You wrote it in assembly language and you knew exactly how
long an instruction took to execute, so it was simple arithmatic. Now
a days you have little idea what the processor really is doing......
Andrew
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next prev parent reply other threads:[~2006-05-30 7:53 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 [this message]
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
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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