RE: [ECOS] to consume cpu time

RE: [ECOS] to consume cpu time

[Doug Fraser]

One method of forcing nanosecond delays that I have
used is to read from FLASH. It is usually not cached
(to avoid programming problems) and also responds
in fixed time to a read cycle for most hardware.
For example, on our MPC850 based hardware, a FLASH
read (Intel Strata) responds in exactly 150nS.
You can get very consistent delay loops this way.

Doug Fraser

> -----Original Message-----
> From: Nick Garnett [mailto:nickg@ecoscentric.com]
> Sent: Wednesday, October 22, 2003 6:17 AM
> To: Luca Formaggio
> Cc: ecos-discuss@sources.redhat.com
> Subject: Re: [ECOS] to consume cpu time
> 
> 
> Luca Formaggio <luca_formaggio@yahoo.it> writes:
> 
> > Hi. I need to consume a cpu time in a program. This
> > time is in nanoseconds. Is there a ecos function that
> > consume time in nanoseconds? If it exists, how I call
> > this function from my program?
> 
> There's nothing in eCos that can handle that. The best we have is
> HAL_DELAY_US() which approximates a given microsecond delay.
> 
> If you want to insert delays for sub-microsecond periods then the best
> approach is probably to use timed code loops. Even then, your timing
> is going to be thrown out by any interupts. Even cache misses or DRAM
> refresh cycles may affect you.
> 
> -- 
> Nick Garnett                    eCos Kernel Architect
> http://www.ecoscentric.com      The eCos and RedBoot experts
> 
> 
> -- 
> Before posting, please read the FAQ: 
> http://sources.redhat.com/fom/ecos
> and search the list archive: http://sources.redhat.com/ml/ecos-discuss
> 

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Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
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Re: [ECOS] to consume cpu time

[Nick Garnett]

Luca Formaggio <luca_formaggio@yahoo.it> writes:

> Hi. I need to consume a cpu time in a program. This
> time is in nanoseconds. Is there a ecos function that
> consume time in nanoseconds? If it exists, how I call
> this function from my program?

There's nothing in eCos that can handle that. The best we have is
HAL_DELAY_US() which approximates a given microsecond delay.

If you want to insert delays for sub-microsecond periods then the best
approach is probably to use timed code loops. Even then, your timing
is going to be thrown out by any interupts. Even cache misses or DRAM
refresh cycles may affect you.

-- 
Nick Garnett                    eCos Kernel Architect
http://www.ecoscentric.com      The eCos and RedBoot experts


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Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
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[ECOS] to consume cpu time

[Luca Formaggio]

Hi. I need to consume a cpu time in a program. This
time is in nanoseconds. Is there a ecos function that
consume time in nanoseconds? If it exists, how I call
this function from my program?

Thanks

Luca Formaggio


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