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Date:	Fri, 2 Feb 2007 08:13:27 +0100
From:	Andi Kleen <ak@...e.de>
To:	Jiri Bohac <jbohac@...e.cz>
Cc:	linux-kernel@...r.kernel.org, Vojtech Pavlik <vojtech@...e.cz>,
	ssouhlal@...ebsd.org, arjan@...radead.org, tglx@...utronix.de,
	johnstul@...ibm.com, zippel@...ux-m68k.org, andrea@...e.de
Subject: Re: [patch 4/9] Remove the TSC synchronization on SMP machines

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@...e.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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