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

From: Thomas Gleixner
Date: Mon Mar 22 2010 - 10:22:33 EST


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.

Thanks,

tglx
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