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SubjectRe: [PATCH 2/2] block: Convert BDI proportion calculations to flexible proportions
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On Fri, 2012-06-01 at 00:11 +0200, Jan Kara wrote:
> bool fprop_new_period(struct fprop_global *p, int periods)
> {
> - u64 events = percpu_counter_sum(&p->events);
> + u64 events;
> + unsigned long flags;
>
> + local_irq_save(flags);
> + events = percpu_counter_sum(&p->events);
> + local_irq_restore(flags);
> /*
> * Don't do anything if there are no events.
> */
> @@ -73,7 +77,9 @@ bool fprop_new_period(struct fprop_global *p, int periods)
> if (periods < 64)
> events -= events >> periods;
> /* Use addition to avoid losing events happening between sum and set */
> + local_irq_save(flags);
> percpu_counter_add(&p->events, -events);
> + local_irq_restore(flags);
> p->period += periods;
> write_seqcount_end(&p->sequence);

Uhm, why bother enabling it in between? Just wrap the whole function in
a single IRQ disable.


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