Re: [REPORT] cfs-v4 vs sd-0.44

Ingo Molnar
2007-04-24T07:31:33Z

* Rogan Dawes <lists@dawes.za.net> wrote:

> > if (p_to && p->wait_runtime > 0) {
> > p->wait_runtime >>= 1;
> > p_to->wait_runtime += p->wait_runtime;
> > }
> >
> >the above is the basic expression of: "charge a positive bank balance".
> >
>
> [..]
>
> > [note, due to the nanoseconds unit there's no rounding loss to worry
> > about.]
>
> Surely if you divide 5 nanoseconds by 2, you'll get a rounding loss?

yes. But not that we'll only truly have to worry about that when we'll
have context-switching performance in that range - currently it's at
least 2-3 orders of magnitude above that. Microseconds seemed to me to
be too coarse already, that's why i picked nanoseconds and 64-bit
arithmetics for CFS.

Ingo