On 15/02/17 14:33, Daniel Bristot de Oliveira wrote: > On 02/15/2017 01:59 PM, Juri Lelli wrote: > > Actually, another thing that we noticed, talking on IRC with Peter, is > > that we seem to be replenishing differently on different occasions: > > When a task is awakened (not by the replenishment timer), it is not > possible to know if the absolute deadline var stores the absolute > deadline of activation which took place in the instant > (current time) - dl_period. > > Therefore, assuming the next deadline is one dl_deadline away from now > is correct. > > IOW: that is a sporadic activation - the task is activated after at > least minimum inter-arrival time between activation/replenishment: > > > - on wakeup (if overflowing) we do > > > > dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; > > dl_se->runtime = pi_se->dl_runtime; > > > In the replenishment timer, it is known that the absolute deadline > instant of the previous activation is in the deadline var. So > putting the absolute deadline one dl_period away is correct [1]. > > Another point is that this case avoids creating time drift due > to latencies. For instance, in the case of a 1 ms delay of the timer > (interrupts disabled?), the wakeup replenishment would push the > absolute a relative deadline + 1 ms away from the previous deadline. > > IOW: the replenishment timer makes the periodic case - a fixed time > offset from the previous activation/replenishment. > > > - when the replenishment timer fires (un-thottle and with runtime < 0) > > > > dl_se->deadline += pi_se->dl_period; > > dl_se->runtime += pi_se->dl_runtime; > > So I think it is correct. Am I missing something? >
Nope, you are right, no problems here. Thanks, - Juri
