Re: [Xen-devel] [PATCH] xen/sched: Remove d->is_pinned

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 01.04.19 at 12:09, <andrew.cooper3@xxxxxxxxxx> wrote:
> 3) cpumask_weight() is a surprisingly expensive function, and we use it all
>    over the place.  It will almost certainly benefit from the use of popcnt.

FTR this was something I was meaning to possibly do once the BMI2
alternatives patching series would have been accepted. It having
got rejected (and also the fsgsbase patching one, but that's moot
now anyway due to selection of insn having become dependent on a
runtime property), I've stopped all considerations towards further
alternatives. While there wouldn't be as many helper functions
needed here as they were needed there, our basic disagreement
as to whether to use per-register helper functions would continue
to exist.

> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -1229,7 +1229,7 @@ arch_do_vcpu_op(
>          struct vcpu_get_physid cpu_id;
>  
>          rc = -EINVAL;
> -        if ( !is_pinned_vcpu(v) )
> +        if ( !is_hwdom_pinned_vcpu(v) )
>              break;

I think the idea here was to allow eventual use of this in a highly
disaggregated environment by other than Dom0. But this is not
to say that I would mind this change; in fact
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Jan



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