Messages in this thread | | | Date | Mon, 10 Sep 2012 23:35:19 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH tip/core/rcu 04/26] rcu: Settle config for userspace extended quiescent state |
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On Tue, Sep 04, 2012 at 05:46:19PM -0700, Josh Triplett wrote: > > It actually does depend on SMP. There has to be at least one CPU taking > > scheduling-clock interrupts in order to keep time computation accurate, > > so a de-facto UP system cannot adaptive-dynticks its sole CPU. > > Ah. That seems like a removable limitation, albeit a difficult one. > Nonetheless, it makes sense to avoid providing the option when it won't > help. > > However, once a config symbol for adaptive dynticks exists, perhaps that > symbol should depend on SMP and RCU_USER_QS should depend on that > instead, documenting the limitation in the right place and making it > easier to find and change eventually.
Right! And in fact CONFIG_RCU_USER_QS is a temporary config. Once we'll have CONFIG_NO_HZ_FULL, we won't need intermediate configs like this. And CONFIG_NO_HZ_FULL will depend on SMP anyway.
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