Re: [PATCH] Added MIPS RM9K watchdog driver

[Ralf Baechle <ralf@linux-mips.org>]

On Sat, Aug 12, 2006 at 06:06:02PM +0200, Thomas Koeller wrote:

> > > + while (1) continue;
> >
> > cpu_relax();
> 
> I tried to find out about the purpose of cpu_relax(). On MIPS, at least,
> it maps to barrier(). I do not quite understand why I would need a
> barrier() in this place. Would you, or someone else, care to
> enlighten me?

Busy wait loops are meant to be filled with cpu_relax() in Linux.  On
processors like the Pentium 4 this expands into something that keeps
the CPU from consuming excessive amounts of energy for just twiddling
thumbs and probably also CPU dependant.  On MIPS cpu_relax() so far is
meaningless and therfore just defined as barrier().

  Ralf