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Re: DSR Scheduling Problem
In gmane.os.ecos.general, you wrote:
>> Isn't ECOS about choice?
Yes.
> Well, unfortunately choice doesn't come for free.
And the new feature you want does?
> More testing, more opportunities for bugs, more confusion,
> etc. I believe useless choices are evil.
Adding a new DSR scheduler doesn't come for free either.
Keeping the old one, however, _is_ free.
>> Make this configurable option and allow users to try both. :-)
>
> Which of the options do you suggest to be the default?
The existing one, of course. Always default to existing
behavior when adding new options.
> How do you explain users the criteria to choose one algorithm
> or another?
You don't. Just explain the differences between the two
algorithms. It's up to the user to determine the criteria on
which he's making his choice.
> How will user compare the choices in his tests when most of
> time the algorithms behave exactly the same?
That's up to the user.
> How do you explain why LIFO choice is there in the first place
> if it has no advantages?
It's already been explained: LIFO is fast and dirt-simple.
> For example, the "array" choice for DSR queue does have an
> excuse as being interrupts-disable-free, and it has an excuse
> of not being the default as it has potential problems with
> missing DSRs. What's an excuse for keeping LIFO choice?
The most important excuse is not changing things for people who
have working systems. I don't care how much you want FIFO DSR
scheduling -- you don't get to force it down my throat.
> The only one I see is backward compatibility, but due to the
> fact that eCos never specified exact order of DSRs it
> shouldn't matter.
Lots of things that shouldn't matter do. Don't arbitrarily
force changes on everybody just to make a tiny minority happy.
I'm all for allowing that minority to add another DSR
scheduling option if they want. I'm _not_ for allow them to
force that change on everybody else.
--
Grant Edwards grante Yow! Put FIVE DOZEN red
at GIRDLES in each CIRCULAR
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