Re: [PATCH v11 3/4] softmmu/dirtylimit: implement virtual CPU throttle

[Hyman Huang]

> > +static void *dirtylimit_thread(void *opaque)
> > +{
> > +    CPUState *cpu;
> > +
> > +    rcu_register_thread();
> > +
> > +    while (!qatomic_read(&dirtylimit_quit)) {
> > +        sleep(DIRTYLIMIT_CALC_TIME_MS / 1000);
>
> Sorry to have not mentioned this: I think we probably don't even need this
> dirtylimit thread.
>
> It'll be hard to make the "sleep" right here.. you could read two identical
> values from the dirty calc thread because the 1sec sleep is not accurate, so
> even after this sleep() the calc thread may not have provided the latest number
> yet.
>
> It'll be much cleaner (and most importantly, accurate..) to me if we could make
> this a hook function being passed over to the vcpu_dirty_rate_stat_thread()
> thread, then after each vcpu_dirty_rate_stat_collect() we call the hook.
Ok, i remove the dirtylimit_thread and implemtment throttle in bottom 
half instead, indeed, it become more accurate. Anyway, how do you think 
of it?
> > +
> > +        dirtylimit_state_lock();
> > +
> > +        if (!dirtylimit_in_service()) {
> > +            dirtylimit_state_unlock();
> > +            break;
> > +        }
> > +
> > +        CPU_FOREACH(cpu) {
> > +            if (!dirtylimit_vcpu_get_state(cpu->cpu_index)->enabled) {
> > +                continue;
> > +            }
> > +            dirtylimit_adjust_throttle(cpu);
> > +        }
> > +        dirtylimit_state_unlock();
> > +    }
> > +
> > +    rcu_unregister_thread();
> > +
> > +    return NULL;
> > +}
> > +



--
Best regard

Hyman Huang(黄勇)