On Wed, 2016-02-24 at 10:43 +0000, George Dunlap wrote: > On 12/02/16 16:29, Dario Faggioli wrote: > > > > @@ -1022,11 +1037,18 @@ csched_vcpu_wake(const struct scheduler > > *ops, struct vcpu *vc) > > * more CPU resource intensive VCPUs without impacting > > overall > > * system fairness. > > * > > - * The one exception is for VCPUs of capped domains unpausing > > - * after earning credits they had overspent. We don't boost > > - * those. > > + * There are two cases, when we don't want to boost: > > + * - VCPUs that are waking up after a migration, rather than > > + * after having block; > > + * - VCPUs of capped domains unpausing after earning credits > > + * they had overspent. > > + * > > + * Note that checking whether we are "only" migrating must be > > + * done up front, as we do not want the clearing of the bit we > > + * set in csched_cpu_pick() to be short-circuited away. > > */ > > - if ( svc->pri == CSCHED_PRI_TS_UNDER && > > + if ( !test_and_clear_bit(CSCHED_FLAG_VCPU_MIGRATING, &svc- > > >flags) && > > + svc->pri == CSCHED_PRI_TS_UNDER && > > !test_bit(CSCHED_FLAG_VCPU_PARKED, &svc->flags) ) > > Sorry to be late reviewing this. > No problem. Thanks for getting to it, actually, as I've got a few more patches stacked on top of these outstanding series.
> So we always want to clear the 'migrating' flag, regardless of
> whether
> we do anything with boosting. Would that logic be clearer if we
> cleared
> it as a separate step, storing the result in a local variable? E.g.:
>
> bool migrating;
>
> ...
>
> /* Always clear migrating flag if it's set */
> migrating = test_and_clear_bit(...)
>
> if ( !migrating && ...) {
> }
>
> Then we wouldn't need the last paragraph in the comment.
>
Yes, I think I like this better.
> That said, this is v3, so if you'd rather just get this in as it is,
> then you can have my Acked-by as well.
>
No, I'll resend... If I make (only) this change, can I resend directly
with your Acked-by?
Thanks and Regards,
Dario
--
<<This happens because I choose it to happen!>> (Raistlin Majere)
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Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
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