Re: [Xen-devel] [PATCH 18/19] xen: credit2: implement SMT support independent runq arrangement

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On Sat, Jun 18, 2016 at 12:13 AM, Dario Faggioli
<dario.faggioli@xxxxxxxxxx> wrote:
> In fact, right now, we recommend keepeing runqueues
> arranged per-core, so that it is the inter-runqueue load
> balancing code that automatically spreads the work in an
> SMT friendly way. This means that any other runq
> arrangement one may want to use falls short of SMT
> scheduling optimizations.
>
> This commit implements SMT awareness --similar to the
> one we have in Credit1-- for any possible runq
> arrangement. This turned out to be pretty easy to do,
> as the logic can live entirely in runq_tickle()
> (although, in order to avoid for_each_cpu loops in
> that function, we use a new cpumask which indeed needs
> to be updated in other places).
>
> In addition to disentangling SMT awareness from load
> balancing, this also allows us to support the
> sched_smt_power_savings parametar in Credit2 as well.
>
> Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>

Other than the issues Jan pointed out, looks good.

 -George

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