Messages in this thread | | | Date | Thu, 17 Mar 2016 08:36:05 +0100 | From | Peter Zijlstra <> | Subject | Re: RFC on fixing mutex spinning on owner |
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On Wed, Mar 16, 2016 at 10:17:51PM -0400, Steven Rostedt wrote: > Actually, the preempt off section here is not really an issue: > > rcu_read_lock(); > while (owner_running(lock, owner)) { > if (need_resched()) > break; > > cpu_relax_lowlatency(); > } > rcu_read_unlock(); > > Although preemption may be disabled, that "need_resched()" check will > break out of the loop if a higher priority task were to want to run on > this CPU. > > I probably should add a hook there to let the preemptoff tracer know > that this is not an issue.
Urgh, there's a lot of such spin loops all over, that's going to be a pain to annotate all.
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