Re: [PATCH] sched/fair: Prefer idle CPU to cache affinity

[Peter Zijlstra]

On Fri, Feb 26, 2021 at 10:10:29PM +0530, Srikar Dronamraju wrote:
> +static int prefer_idler_llc(int this_cpu, int prev_cpu, int sync)
> +{
> +	struct sched_domain_shared *tsds, *psds;
> +	int pnr_busy, pllc_size, tnr_busy, tllc_size, diff;
> +
> +	tsds = rcu_dereference(per_cpu(sd_llc_shared, this_cpu));
> +	tnr_busy = atomic_read(&tsds->nr_busy_cpus);
> +	tllc_size = per_cpu(sd_llc_size, this_cpu);
> +
> +	psds = rcu_dereference(per_cpu(sd_llc_shared, prev_cpu));
> +	pnr_busy = atomic_read(&psds->nr_busy_cpus);
> +	pllc_size = per_cpu(sd_llc_size, prev_cpu);
> +

nr_busy_cpus is NO_HZ_COMMON So this code that consumes it should be
too.