Messages in this thread |  | | From | Vincent Guittot <> | Date | Thu, 7 Jun 2018 10:44:26 +0200 | Subject | Re: [PATCH v5 07/10] sched/irq: add irq utilization tracking |
| |
On 7 June 2018 at 10:29, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote: > On 06/06/2018 06:06 PM, Vincent Guittot wrote: >> >> Hi Dietmar, >> >> Sorry for the late answer >> >> On 31 May 2018 at 18:54, Dietmar Eggemann <dietmar.eggemann@arm.com> >> wrote: >>> >>> On 05/30/2018 08:45 PM, Vincent Guittot wrote: >>>> >>>> Hi Dietmar, >>>> >>>> On 30 May 2018 at 17:55, Dietmar Eggemann <dietmar.eggemann@arm.com> >>>> wrote: >>>>> >>>>> On 05/25/2018 03:12 PM, Vincent Guittot wrote: >>> >>> >>> [...] >>> >>>>>> + */ >>>>>> + ret = ___update_load_sum(rq->clock - running, rq->cpu, >>>>>> &rq->avg_irq, >>>>>> + 0, >>>>>> + 0, >>>>>> + 0); >>>>>> + ret += ___update_load_sum(rq->clock, rq->cpu, &rq->avg_irq, >>>>>> + 1, >>>>>> + 1, >>>>>> + 1); >>> >>> >>> Can you not change the function parameter list to the usual >>> (u64 now, struct rq *rq, int running)? >>> >>> Something like this (only compile and boot tested): >> >> >> To be honest, I prefer to keep the specific sequence above in a >> dedicated function instead of adding it in core code. > > > No big issue. > >> Furthermore, we end up calling call twice ___update_load_avg instead >> of only once. This will set an intermediate and incorrect value in >> util_avg and this value can be read in the meantime > > > Can't buy this argument though because this is true with the current > implementation as well since the 'decay load sum' - 'accrue load sum' > sequence is not atomic.
it's not a problem that the _sum variable are updated in different step because there are internal variable Only util_avg is used "outside" and the latter is updated after both idle and running steps have been applied
> > What about calling update_irq_load_avg(rq, 0) in update_rq_clock_task() if > (irq_delta + steal) eq. 0 and sched_feat(NONTASK_CAPACITY) eq. true in this > #ifdef CONFIG_XXX_TIME_ACCOUNTING block?
update_irq_load_avg(rq, 0) is called in update_blocked_averages to decay smoothly like other blocked signals and replace the need to call update_irq_load_avg(rq, 0) for every call to update_rq_clock_task() which can be significant
> > Maintaining a irq/steal time signal makes only sense if at least one of the > CONFIG_XXX_TIME_ACCOUNTING is set and NONTASK_CAPACITY is true. The call to > update_irq_load_avg() in update_blocked_averages() isn't guarded my them.
good point
> > [...]
|  |