Re: [PATCH V2 3/4] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task

On Tue, Nov 15, 2016 at 01:53:22PM +0530, Viresh Kumar wrote:

@@ -308,7 +313,21 @@ static void sugov_irq_work(struct irq_work *irq_work) struct sugov_policy *sg_policy; sg_policy = container_of(irq_work, struct sugov_policy, irq_work);

• /*

• * For Real Time and Deadline tasks, schedutil governor shoots the
  

• * frequency to maximum. And special care must be taken to ensure that
  

• * this kthread doesn't result in that.
  

• *
  

• * This is (mostly) guaranteed by the work_in_progress flag. The flag is
  

• * updated only at the end of the sugov_work() and before that schedutil
  

• * rejects all other frequency scaling requests.
  

• *
  

• * Though there is a very rare case where the RT thread yields right
  

• * after the work_in_progress flag is cleared. The effects of that are
  

• * neglected for now.
  

• */
  

• kthread_queue_work(&sg_policy->worker, &sg_policy->work);

}

Right, so that's a wee bit icky, but its also entirely pre-existing code.

Acked-by: Peter Zijlstra (Intel) peterz@infradead.org