Re: [GIT pull] ntp updates for 2.6.31
From: Miroslav Lichvar
Date: Tue Jun 23 2009 - 15:49:43 EST
On Tue, Jun 23, 2009 at 09:18:38PM +0200, Ingo Molnar wrote:
> * Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:
> > > > I'm not very familiar with the PPS API, is there something
> > > > wrong with it?
> > >
> > > The PPS patches i've seen just export IRQ timestamps to
> > > user-space.
> > >
> > > That is not very robust in my opinion when it comes to do time
> > > approximations - to get quick, low-latency action and precise
> > > measurements it's best to keep the critical path as short as
> > > possible, and within a single source code repository: i.e.
> > > within the kernel.
> > That's what kernel PPS discipline does, it will be probably
> > included later. Its performance is an order or two better than the
> > PLL/FLL discipline.
> Is there some kernel patch i can look at?
It's in the old PPSkit patches for 2.4 kernels, function hardpps().
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