[parisc-linux] Generic light-weight syscall.

[Richard Hirst]

On Mon, Jul 28, 2003 at 08:14:20PM +0100, Matthew Wilcox wrote:
> On Mon, Jul 28, 2003 at 03:04:55PM -0400, Carlos O'Donell wrote:
> > > You know, you don't even need kernel help for this.  According to page
> > > 2-5 of the Kane book, the Interval Timer is accessible by non-privileged
> > > instructions.
> > 
> > Isn't this going to be different for all CPU's? Which means if you get
> > scheduled around you might see negative moving time?
> 
> We discussed this in the Black Thorn ... record what value you last
> returned to the user and never return less than that.

Not very nice if the difference between CPUs is significant.  You could
find yourself checking time on CPU A, doing some work, getting moved to
CPU B, checking time, and finding you apparently did all that in 0ns.

Richard