Messages in this thread | | | Date | Wed, 19 Feb 2014 09:46:18 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3] sched/deadline: Fix bad accounting of nr_running |
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On Tue, Feb 18, 2014 at 09:50:12PM -0500, Steven Rostedt wrote: > > > Rationale for this odd behavior is that, when a task is throttled, it > > is removed only from the dl_rq, but we keep it on_rq (as this is not > > a "full dequeue", that is the task is not actually sleeping). But, it > > is also true that, while throttled a task behaves like it is sleeping > > (e.g., its timer will fire on a new CPU if the old one is dead). So, > > Steven's fix sounds also semantically correct. > > Actually, it seems that I was hitting it again, but this time getting a > negative number. OK, after looking at the code a bit more, I think we > should update the runqueue nr_running only when the task is officially > enqueued and dequeued, and all accounting within, will not touch that > number.
But if the task is throttled it should still very much decrement the number. There's places that very much rely on nr_running be exactly the number of runnable tasks.
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