Re: [RFC][PATCH] Convert alpha to use clocksource

From: Johannes Weiner
Date: Mon Mar 22 2010 - 12:41:52 EST


On Mon, Mar 22, 2010 at 03:22:12PM +0100, Thomas Gleixner wrote:
> On Mon, 22 Mar 2010, Johannes Weiner wrote:
> > > Though, even after a glance over the clocksource code, I've not
> > > gotten yet to how one could estimate the "shift" value...
> > > Any hints?
> >
> > I had the same problem with xtensa and added a comment about what I
> > did in there, maybe it helps:
> >
> > arch/xtensa/kernel/time.c
> >
> > I took the upper bound of the multiplicator (nsecs per counter unit)
> > and subtracted its logarithm from my available 32 bits. The result
> > is the highest possible shift value that works for the clocksource.
>
> clocks_calc_mult_shift() is what you are looking for.

Oh, thanks! That was not yet around at the time.

Hannes

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