Messages in this thread | | | Date | Fri, 28 Oct 2016 20:27:12 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/4] sched: move IO scheduling accounting from io_schedule_timeout() to __schedule() |
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On Fri, Oct 28, 2016 at 12:58:09PM -0400, Tejun Heo wrote: > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -3336,11 +3336,17 @@ static void __sched notrace __schedule(bool preempt) > unsigned long *switch_count; > struct pin_cookie cookie; > struct rq *rq; > - int cpu; > + int cpu, in_iowait; > > cpu = smp_processor_id(); > rq = cpu_rq(cpu); > prev = rq->curr; > + in_iowait = prev->in_iowait; > + > + if (in_iowait) { > + delayacct_blkio_start(); > + atomic_inc(&rq->nr_iowait); > + } > > schedule_debug(prev); > > @@ -3406,6 +3412,11 @@ static void __sched notrace __schedule(bool preempt) > } > > balance_callback(rq); > + > + if (in_iowait) { > + atomic_dec(&rq->nr_iowait); > + delayacct_blkio_end(); > + } > } > > void __noreturn do_task_dead(void)
Urgh, can't say I like this much. It moves two branches into the schedule path.
Nor do I really like the idea of having to annotate special mutexes for the iowait crap.
I'll think more after KS/LPC etc..
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