Re: Linus... (or anyone) and timeloss in joystick driver.

Michael Weller (
Tue, 27 Jun 1995 11:41:00 +0200 (MSZ)

On Tue, 27 Jun 1995, Harald Koenig wrote:

> You write:

> > I don't think the loss of 3.4 ms is THAT important to the joystick driver.
> > You trigger a new AD conversion and.. well you just read it back some
> > time later. The program using the joystick should disable itself anyway
> > if the console is switched away, so it really makes no difference.
> 3.4ms would be really *bad* for other operations too, e.g.:
> one character at 38400 baud is 0.26 ms, so in 3.4ms one serial line
> could receive ~13 characters! even with a 16550A uart with 16 byte FIFO
> this might result in lost characters!

Well.. at first, I dunno how he measured the 3.4ms. So it might be actually
shorter. However if they are due to the console switch, irq's will be enabled
during vc switching anyway.

That means there will be no lost chars as the uart is handled as usual.
It merely means that scheduling will stop for 3.4 ms. Well, no one ever
said linux is a real time os.


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