Re: [RFC PATCH 2/3] softirq: implement interrupt flood detection

[Peter Zijlstra <peterz@infradead.org>]

On Wed, Dec 18, 2019 at 11:49:41AM +0100, Peter Zijlstra wrote:
> 
> _If_ you want to do something like this, do it like the below. That only
> adds a few instruction to irq_exit() and only touches a cacheline that's
> already touched.
> 
> It computes both the avg duration and the avg inter-arrival-time of
> hardirqs. Things get critical when:
> 
> 	inter-arrival-avg < 2*duration-avg
> 
> or something like that.

Better yet, try something like:

bool cpu_irq_heavy(int cpu)
{
	return cpu_util_irq(cpu_rq(cpu)) >= arch_scale_cpu_capacity(cpu);
}