Re: [RFC 1/1] Weighted approach to gather and use history in TEO governor

[Pratik Sampat]

On 13/05/20 8:19 pm, Rafael J. Wysocki wrote:
> On Wed, May 13, 2020 at 7:31 AM Pratik Sampat <psampat@xxxxxxxxxxxxx> wrote:
> > Thanks for your comment.
> >
> >
> > On 12/05/20 11:07 pm, Peter Zijlstra wrote:
> > > Just a quick note..
> > >
> > > On Mon, May 11, 2020 at 07:40:55PM +0530, Pratik Rajesh Sampat wrote:
> > >
> > > > +    /*
> > > > +     * Rearrange the weight distribution of the state, increase the weight
> > > > +     * by the LEARNING RATE % for the idle state that was supposed to be
> > > > +     * chosen and reduce by the same amount for rest of the states
> > > > +     *
> > > > +     * If the weights are greater than (100 - LEARNING_RATE) % or lesser
> > > > +     * than LEARNING_RATE %, do not increase or decrease the confidence
> > > > +     * respectively
> > > > +     */
> > > > +    for (i = 0; i < drv->state_count; i++) {
> > > > +            unsigned int delta;
> > > > +
> > > > +            if (idx == -1)
> > > > +                    break;
> > > > +            if (i ==  idx) {
> > > > +                    delta = (LEARNING_RATE * cpu_data->state_mat[last_idx][i]) / 100;
> > > 100 is a crap number to divide by as a computer. We bio-puddings happend
> > > to have 10 digits, so 100 makes sense to us, but it does not to our
> > > binary friends.
> > Absolutely! I just wrote the code exactly the way I did the Math on paper,
> > definitely need to figure out an optimal way of doing things.
> There is no particular reason to use percent in computations at all.
> You may as well use 1/1024 parts instead (and then use shifts instead
> of divisions).

Yes you're right. Looking at it now the whole percent system and divisions
does seem quite unnecessary and we can achieve it rather with bitwise
operations.

Thanks!