From: Andi Kleen <ak@suse.de>
To: Jiri Bohac <jbohac@suse.cz>
Subject: Re: [patch 2/9] Remove the support for the VXTIME_PMTMR timer mode
Date: Thu, 1 Feb 2007 15:18:47 +0100
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Cc: linux-kernel@vger.kernel.org, Vojtech Pavlik <vojtech@suse.cz>,
       ssouhlal@freebsd.org, arjan@infradead.org, tglx@linutronix.de,
       johnstul@us.ibm.com, zippel@linux-m68k.org, andrea@suse.de
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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@suse.cz 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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