[patch] hp-timing for powerpc64

Benjamin Herrenschmidt benh@kernel.crashing.org
Mon Jun 20 04:28:00 GMT 2005


On Sat, 2005-06-18 at 18:39 +0200, matthieu castet wrote:
> Ulrich Drepper wrote:
> > Paul Mackerras wrote:
> > 
> > 
> >>Do we use rdtsc on x86 machines?  If not rdtsc, what do we use?
> > 
> > 
> > Yes, we do, but at least it means that each unit is one cycle of t he
> > CPU which then can be translated into seconds.  From what I know this
> > isn't the case with mftb, where different implementations increment the
> > counter differently.
> > 
> the timebase for converting ppc timestamp into second are avaible in 
> /proc/cpuinfo.
> 
> I don't know how the linux kernel compute it (a grep ppc_tb_freq 
> arch/ppc64/kernel should provide some info).

Parsing /proc is ugly though ... It would be useful to add something
nicer, like a vDSO entry point exposed by glibc or something like
that...


Ben.




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