Re: [PATCH 2/3] sched/core: Introduce nr_running percpu for each cookie

[Peter Zijlstra]

On Tue, Jun 28, 2022 at 03:57:24PM +0800, Cruz Zhao wrote:

>  static unsigned long sched_core_alloc_cookie(void)
>  {
>  	struct sched_core_cookie *ck = kmalloc(sizeof(*ck), GFP_KERNEL);
> +	int cpu;
> +
>  	if (!ck)
>  		return 0;
>  
>  	refcount_set(&ck->refcnt, 1);
> +
> +	ck->nr_running = alloc_percpu(unsigned int);

	if (!ck->nr_running)
		// do something

> +	for_each_possible_cpu(cpu)
> +		*per_cpu_ptr(ck->nr_running, cpu) = 0;

So I really, as in *really* dislike how this blows up the size of
cookies. Esp. with 100s of CPUs not actually being rare these days.