[parisc-linux] Generic light-weight syscall.

Richard Hirst rhirst@linuxcare.com
Tue, 29 Jul 2003 22:06:09 +0100

On Tue, Jul 29, 2003 at 01:50:58PM -0400, Carlos O'Donell wrote:
> > > 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.
> Willy and myself talked about this, you just return 1ns in the case
> where you know that _something_ must have taken _some_ amount of time
> (e.g. the insns that make up fast gettimeofday) so you couldn't have done
> it in zero time :)

Depends what people want to use it for.  I couldn't use it to time how
long some syscall took, for example.  But if we zap the microseconds
part on smp anyway, that's irrelevant.