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Date: Wed, 8 Dec 2004 15:47:21 -0800 (PST)
From: Christoph Lameter <clameter@sgi.com>
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To: George Anzinger <george@mvista.com>
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Subject: Re: [RFC] New timeofday proposal (v.A1)
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On Wed, 8 Dec 2004, George Anzinger wrote:

> Right.  We seem to be doing ok now by just adjusting things at tick time and
> using the "normal" interpolation between ticks.
>
> As for the math, the current code keeps a running "remainder" which is the
> amount of the correction that was finer than the clock resolution (i.e. less
> than a nano second) and rolls this in on the next tick.  This gives resolution
> out to several bits to the right of the nano second.  And I think this is all
> done with 32 bit math (if memory serves).

That is probably the i386 version with which I am not familiar. The time
interpolator logic (IA64 and SPARC64) does fine with a scaled 64 bit
factor without a remainder. The factor may be used to express fractions of
nanoseconds.