Re: [f-cpu] More on Interrupts

[Michael Riepe <michael@stud.uni-hannover.de>]

On Fri, Jan 18, 2002 at 08:28:50AM -0700, Ben Franchuk wrote:
> richard hartny wrote:
> Nowdays 32 interrupt vectors should be standard.

For 32-bit CPUs, yes.

> Also since most modern OS do a task swap after
> a interrupt a fast way of of setting task priorities
> and getting the next sorted task would be useful.

Since interrupts tend to arrive frequently, interrupt service routines
should return to the interrupted task as soon as possible. A task
switch, on the other hand, is rather expensive -- a lot of state has
to be saved and reloaded, even with SRB.

Most interrupts deal with I/O - they indicate that data has arrived or
can be sent, or that some device has changed its state. Usually, none
of these events triggers an automatic task switch.

-- 
 Michael "Tired" Riepe <Michael.Riepe@stud.uni-hannover.de>
 "All I wanna do is have a little fun before I die"
*************************************************************
To unsubscribe, send an e-mail to majordomo@seul.org with
unsubscribe f-cpu       in the body. http://f-cpu.seul.org/