Re: [Xen-devel] [PATCH 3/3] xen: credit1: avoid boosting vCPUs being "just" migrated

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 11.02.16 at 12:39, <dario.faggioli@xxxxxxxxxx> wrote:
> --- a/xen/common/sched_credit.c
> +++ b/xen/common/sched_credit.c
> @@ -1022,11 +1022,14 @@ csched_vcpu_wake(const struct scheduler *ops, struct 
> vcpu *vc, unsigned wf)
>       * 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 a couple of exceptions, 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.
>       */
> -    if ( svc->pri == CSCHED_PRI_TS_UNDER &&
> +    if ( !(wf & WF_migrated) &&
> +         svc->pri == CSCHED_PRI_TS_UNDER &&
>           !test_bit(CSCHED_FLAG_VCPU_PARKED, &svc->flags) )
>      {

Considering the other svc->flags check done here, wouldn't it be
possible to achieve the same effect without patch 2, by having
csched_cpu_pick() set a newly defined flag, and check for it here?

Jan


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