Messages in this thread | | | Date | Mon, 30 Sep 2013 20:37:47 +0200 | From | Daniel Lezcano <> | Subject | Re: [PATCH 19/21] cpuidle: create list of registered drivers |
| |
On 09/28/2013 11:33 PM, Paul E. McKenney wrote: > On Thu, Sep 26, 2013 at 10:19:14AM +0200, Daniel Lezcano wrote: >> 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 > > But you should be able to use SRCU in the idle path, if that helps.
Interesting, thanks for the pointer.
-- Daniel
-- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog
-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |