Re: [RFC] New timeofday proposal (v.A1)
From: Christoph Lameter
Date: Wed Dec 08 2004 - 18:50:11 EST
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.
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