Messages in this thread | | | Date | Thu, 26 Sep 2013 10:19:14 +0200 | From | Daniel Lezcano <> | Subject | Re: [PATCH 19/21] cpuidle: create list of registered drivers |
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On 09/26/2013 08:17 AM, Viresh Kumar wrote: > On 26 September 2013 04:00, Daniel Lezcano <daniel.lezcano@linaro.org> wrote: >> If you introduce a list, you will have to introduce a lock to protect >> it. > > I missed it, should have added that :) > >> This lock will be in the fast path cpuidle_idle_call with the >> get_driver function and conforming to the comment: "NOTE: no locks or >> semaphores should be used here". >> >> A lock has been introduced in this function already and the system hangs >> with 1024 cpus. > > Hmm... I see.. I didn't knew about this expectation.. What about a rcu > read/write lock? As far as I know its too lightweight... Can we have that > in fast path?
Nope, we can't use rcu in the idle path :)
http://lists.infradead.org/pipermail/linux-arm-kernel/2012-February/083054.html
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