Messages in this thread | | | Subject | Re: CFS rq lock question | From | Peter Zijlstra <> | Date | Fri, 11 Apr 2008 19:37:01 +0200 |
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On Fri, 2008-04-11 at 13:21 -0400, Dan Upton wrote: > I'm poking around with some scheduler stuff, and there's something I'm > not clear on for the CFS runqueue locks. The comments before > __load_balance_iterator(...) in sched_fair.c suggests things can be > dequeued even though the runqueue lock is held. Can things also be > added to the queue while the lock is held? (Also, either way, what's > the rationale that dequeueing is a safe procedure when somebody else > holds a lock?)
/* * Load-balancing iterator. Note: while the runqueue stays locked * during the whole iteration, the current task might be * dequeued so the iterator has to be dequeue-safe. Here we * achieve that by always pre-iterating before returning * the current task: */
I don't think this comment is correct, but if it were, it would only apply to rq->curr, not for any enqueue/dequeue.
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