Subject: Re: splraise?
To: Gordon W. Ross <>
From: Leo Weppelman <>
List: tech-kern
Date: 03/01/1997 22:46:35
Gordon W. Ross wrote:
> Where is it appropriate to use splraise?

My guess is that it would solve some problems with diagnostic printf's
when spltty would be defined in terms of splraise on the atari. There
are places (like the spurious interrupt reports for instance) that
occaisionally crash because somewhere in the tty-code the spl is lowered.

> It is my understanding that in most places, splraise should not be
> necessary (just splbio or whatever) thanks to the following rules:
> splsoftxxx <= min(splbio, splnet, spltty)
> splbio >= max(disk H/W interrupts)
> splnet >= max(network H/W interrupts)
> spltty >= max(tty H/W interrupts)

At least on the atari, this is not true. If it were, they would all
be at spl6() which is clearly unacceptable. I usually schedule a
software interrupt to do most of the work. The hardware interrupt
only does the stuff that needs to be done fast. In fact I am tempted
to define splbio = splnet = spltty = splsoft = spl1.

[ ... ]

> So, can someone explain the rationale for defining splbio and
> friends as splraise?  Also, what is the performance impact?

I sure am interested in the performance impact. I expect it to be
low, but there is no splraise (yet) on the atari to prove it ;-)