Messages in this thread | | | Subject | Re: [PATCH v5 07/10] sched/irq: add irq utilization tracking | From | Dietmar Eggemann <> | Date | Thu, 7 Jun 2018 10:29:15 +0200 |
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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.
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?
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.
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