[Techtalk] Theory vs. practice

Mary Gardiner linuxchix at puzzling.org
Wed Jan 16 11:57:22 EST 2002

On Tue, Jan 15, 2002 at 06:35:22PM -0500, Raven, corporate courtesan
> Quoth Val Henson (Tue, Jan 15, 2002 at 03:29:14PM -0700):
> > What's wrong with this picture?  A Platinum account holder just
> > spent 3 hours waiting for a Gold account holder, when theoretically,
> > the Platinum holder should have had first priority.
> Okay, I can see that that's bad.  Is there a way to quickly check
> which processes are freeing up resources rather than requesting them,
> and then assign a higher priority to those?  Something to the effect
> of "need $100, who's releasing $100?  You?  Up front!".  You could
> even do some sort of secondary categorization, such that if you had a
> Platinum account needing $100, and you had a Gold account waiting to
> deposit $100 and a Silver account waiting to deposit $100, that the
> Gold account would get priority over the silver even under the new
> "who's got $100" system.

Another problem I think that needs to be taken into account is that of
the actual teller being a process. So when, on a single CPU machine, the
teller wants to call out "Hey you, got a fast transaction? Just a cash
deposit in notes?" everything else has to stop.

And in context switched systems, the teller process needs to be switched
into memory - the teller's stack (variables) need to go back into place,
and the platinum or gold process has to go out. And even the thing doing
the switching is of course a process, although it is a kernel process...

So the teller and the bank need to have priorities too...


Mary Gardiner
<mary at puzzling.org>

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