Re: [RFC PATCH 1/3] sched: Introduce new interface for scheduler soft affinity

[Peter Zijlstra]

On Wed, Jun 26, 2019 at 03:47:16PM -0700, subhra mazumdar wrote:
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 1183741..b863fa8 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -652,6 +652,8 @@ struct task_struct {
>  	unsigned int			policy;
>  	int				nr_cpus_allowed;
>  	cpumask_t			cpus_allowed;

You're patching dead code, that no longer exists.

> +	cpumask_t			cpus_preferred;
> +	bool				affinity_unequal;

Urgh, no. cpumask_t is an abomination and having one of them is already
unfortunate, having two is really not sane, esp. since for 99% of the
tasks they'll be exactly the same.

Why not add cpus_ptr_soft or something like that, and have it point at
cpus_mask by default, and when it needs to not be the same, allocate a
cpumask for it. That also gets rid of that unequal thing.