Re: [PATCH 1/2] cpuidle: menu: avoid expensive square root computation

[Rafael J. Wysocki]

On 2/16/2016 8:19 PM, Rasmus Villemoes wrote:
> Computing the integer square root is a rather expensive operation, at
> least compared to doing a 64x64 -> 64 multiply (avg*avg) and, on 64
> bit platforms, doing an extra comparison to a constant (variance <=
> U64_MAX/36).
>
> On 64 bit platforms, this does mean that we add a restriction on the
> range of the variance where we end up using the estimate (since
> previously the stddev <= ULONG_MAX was a tautology), but on the other
> hand, we extend the range quite substantially on 32 bit platforms - in
> both cases, we now allow standard deviations up to 715 seconds, which
> is for example guaranteed if all observations are less than 1430
> seconds.
>
> Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>

Both patches look good to me,  so I'm going to queue them up for 4.6.

If anyone has any issues with that, please let me know.

Thanks,
Rafael