Re: [parisc-linux] Re: [PATCH] Fix the cpumask rewrite

[Matthias Urlichs]

Hi,

Chris Wedgwood:
> On Sun, Jun 27, 2004 at 02:00:03PM +0200, Matthias Urlichs wrote:
> 
> > <heretic>
> > #define jiffies __get_jiffies()
> > </heretic>
> 
> Well, I have that but it's only part of the story.
> 
True.

> As Alan pointed out a suitable API could also make it easier to work
> towards a clock-less system for embedded targets.
> 
Well, drivers do need some way of timing things, else they wouldn't read
jiffies in the first place. So, at minimum, an embedded system would
need a way to trigger a timeout at some specified time in the future.

A simple __get_jiffies() implementation could just set up a 1/HZ-second
timer (and busy-wait for it, and increase its internal jiffies counter)
every tenth call or so. That would probably slow down the whole system
somewhat, but I'd assume it'd mostly work.

-- 
Matthias Urlichs
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