Re: [patch 2/9] Remove the support for the VXTIME_PMTMR timer mode

From: Andi Kleen
Date: Thu Feb 01 2007 - 09:21:25 EST


On Thursday 01 February 2007 14:59, Jiri Bohac wrote:
> On Thu, Feb 01, 2007 at 02:13:00PM +0100, Andi Kleen wrote:
> > On Thursday 01 February 2007 14:13, Jiri Bohac wrote:
> > > On Thu, Feb 01, 2007 at 12:13:31PM +0100, Andi Kleen wrote:
> > > > On Thursday 01 February 2007 10:59, jbohac@xxxxxxx wrote:
> > > > > VXTIME_PMTMR will be replaced by a more generic "Master Timer"
> > > >
> > > > This means we have no fallback if something goes wrong with the Master timer?
> > > >
> > > > A little risky.
> > >
> > > No, either HPET or PM Timer will become the Master Timer (elected
> > > on boot). Master timer is just an abstraction of these, so the
> > > rest of the timekeeping code needn't care which hardware timer is
> > > being used. That's why the VXTIME_PMTMR mode is not needed.
> >
> > But there is no option for the user to force so, is there?
>
> HPET is the default. If it's not available or with the "nohpet"
> commandline option, PM Timer will be used as the Master Timer.

This assumes all your algorithms are always correct.

> If this is not enough, it can be easily fixed in time_init().

I think we want at least one option that forces HPET/PMtimer as primary
time source.

-Andi


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