Re: [RFC] sched_tick with interrupts enabled

["Siddha, Suresh B" <suresh.b.siddha@intel.com>]

On Wed, Oct 18, 2006 at 02:59:07PM -0700, Christoph Lameter wrote:
> load_balancing has the potential of running for some time if f.e.
> sched_domains for a system with 1024 processors have to be balanced.
> We currently do all of that with interrupts disabled. So we may be unable
> to service interrupts for some time. Most of that time is potentially
> spend in rebalance_tick.

Did you see an issue because of this or just theoretical?

> +static void rebalance_tick(unsigned long dummy)
>  {
> +	int this_cpu = smp_processor_id();
> +	struct rq *this_rq = cpu_rq(this_cpu);
> +	enum idle_type idle;
>  	unsigned long this_load, interval, j = cpu_offset(this_cpu);
>  	struct sched_domain *sd;
>  	int i, scale;
>  
> +	idle = (current == this_rq->idle) ? SCHED_IDLE : NOT_IDLE;

We need to add nr_running check too, to determine if we want to do
idle/not-idle balancing. This is in the context of wake_priority_sleeper()

thanks,
suresh