On 17/10/2019 16:11, Peter Zijlstra wrote: > On Thu, Oct 17, 2019 at 12:11:16PM +0100, Quentin Perret wrote:
[...] > It only boosts when 'rq->cfs.avg.util' increases while > 'rq->cfs.avg.util_est.enqueued' remains unchanged (and util > util_est > obv). > > This condition can be true for select_task_rq_fair(), because that is > ran before we do enqueue_task_fair() (for obvious raisins). > >>> I'm still thinking about the exact means you're using to raise C; that >>> is, the 'util - util_est' as cost_margin. It hurts my brain still. >> >> +1 ... > > cost_i = capacity_i / power_i ; for the i-th OPP I get confused by this definition. efficiency=capacity/power but the cs->cost value used in em_pd_get_higher_freq() is defined as cs_cost = cs->power * cpu_max_freq / cs->freq [energy_model.h] > We then do: 'x = util - util_avg' and use that on the first > OPP >= min_freq: > > cost(x) = cost_j + cost_j * x ; freq_j >= min_freq > = cost_j * (1 + x) > > And then we find the highest OPP that has: > > cost_k <= cost(x) [...]