Messages in this thread | | | Date | Thu, 2 Mar 2017 15:38:41 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH] sched/rt: Document why has_pushable_tasks() isn't called with a runqueue lock |
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On Wed, 1 Mar 2017 09:37:01 +0100 Peter Zijlstra <peterz@infradead.org> wrote:
> On Tue, Feb 28, 2017 at 04:48:56PM -0500, Steven Rostedt wrote: > > > + /* > > + * Normally, has_pushable_tasks() would be performed within the > > + * runqueue lock being held. But if it was not set when entering > > "not set" what? I'm having trouble parsing this.
I always forgot that with documentation, pronouns should be avoided.
"But if has_pushable_tasks is false when entering"
> > > + * this hard interrupt handler function, then to have it set would
", then to have it set to true would"
> > + * require a wake up. A wake up of an RT task will either cause a > > + * schedule if the woken task is higher priority than the running > > + * task, or it would try to do a push from the CPU doing the wake > > + * up. Grabbing the runqueue lock in such a case would more likely > > + * just cause unnecessary contention. > > + */ > > if (has_pushable_tasks(rq)) { > > raw_spin_lock(&rq->lock); > > push_rt_task(rq);
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