Daniel,
On Tue, 26 Mar 2019, Daniel Lezcano wrote:
> >> +/*
> >> + * Exponential moving average computation
> >> + */
> >> +static int irq_timings_ema_new(s64 value, s64 ema_old)
> >
> > There is a mixed bag of s64/u64 all over this code. Please stay
> > consistent. We had enough sign confusion bugs in the past.
>
> Right.
>
> I have a question, ema_old and value will be always u64 type and the
> function irq_timings_ema_new() will return an u64 ...
>
> > value = (value - ema_old) * EMA_ALPHA_VAL;
> > return ema_old + value >> EMA_ALPHA_SHIFT;
>
> ... how can I deal with the operations above when value < ema_old ?
>
> Shall I use an intermediate s64 ?
>
> eg:
>
> s64 aux = (value - ema_old) * EMA_ALPHA_VAL;
> return ema_old + aux >> EMA_ALPHA_SHIFT;
> ?
That should work if ema_old is not ever having the topmost bit set :)
Thanks,
tglx
