From: Andi Kleen <ak@suse.de>
To: Jiri Bohac <jbohac@suse.cz>
Subject: Re: [patch 4/9] Remove the TSC synchronization on SMP machines
Date: Fri, 2 Feb 2007 08:13:27 +0100
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       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 14:17, Jiri Bohac wrote:
> On Thu, Feb 01, 2007 at 12:14:23PM +0100, Andi Kleen wrote:
> > On Thursday 01 February 2007 10:59, jbohac@suse.cz wrote:
> > > TSC is either synchronized by design or not reliable
> > > to be used for anything, let alone timekeeping.
> > 
> > In my tree this is already done better by a patch from Ingo.
> > Check if they look synchronized and don't use TSC if they are not.
> 
> The whole purpose of this patchset is to make use of TSC even if
> it's not synchronized.

It's still useful as a double check for platforms (like Intel single node) 
which are supposed to be synchronized.
 
> Synchronizing it will not make anything better in any way -- the
> implementation just does not care whether TSCs are synchronized.
> That's why I think the synchronization code is not needed.

It doesn't actively synchronize it, just checks if they look synchronized.

-Andi 
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