Messages in this thread | | | Date | Thu, 19 Mar 2009 07:02:21 -0700 | From | Arjan van de Ven <> | Subject | Re: Question about usage of RCU in the input layer |
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On Thu, 19 Mar 2009 00:23:56 -0700 Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
> Hi Arjan, > > On Wednesday 18 March 2009 21:58:12 Arjan van de Ven wrote: > > Hi, > > > > the input layer does a "synchronize_rcu()" after a > > list_add_tail_rcu(), which is costing me 1 second of boot time..... > > And based on my understanding of the RCU concept, you only need to > > synchronize on delete, not on addition... so I think the > > synchronize is entirely redundant here... > > > It is there to guarantee that once we registered the handle all > subsequent input events will be delivered through it.
afaik rcu already guarantees that even without a synchronize; the only reason you would need a synchronize is to guarantee that people STOPPED using your memory. Or am I now totally misunderstanding RCU ?
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