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Laurent GONZALEZ wrote:
> > But that would result in arbitrary delays that are visible to the
> > application. You would need to pick some delay value at random, or
> > make it a configuration parameter. I find this undesirable; it is
> > not the driver's business to enforce this kind of policy decision
> > upon the application. If it needs to transfer data at a rate that
> > significantly loads the CPU in order to serve its purpose (maybe in
> > bursts only), than it must be able to do so.
>
> Yes, the delay is arbitrary, and the value is choosen at random. But
> most of the available high performance chip (e.g. 16x5x family)
> integrate such arbitrary timeout. I work with some of them and they
> provide a delay around 4 chars (40 bit). I don't think that a delay of
> ... 20 bit for example, is undesirable. You may at least recompute it in
> function of the speed to be x microseconds.
If you choose a timeout that is very short, you can get CPU load values
close to the limit, so not much is gained in this case. If you make it
longer, you create irritating delays. One way or another, you loose.
Why at all would you want to have such delays if they can easily be
avoided? If you really want to throttle communication to limit CPU
load, that would best be done in the application.
tk
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Thomas Koeller, Software Development
Basler Vision Technologies
An der Strusbek 60-62
22926 Ahrensburg
Germany
Tel +49 (4102) 463-162
Fax +49 (4102) 463-239
mailto:thomas.koeller@baslerweb.com
http://www.baslerweb.com
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