Messages in this thread | | | Subject | Re: [PATCH 1/2] srcu-3: RCU variant permitting read-side blocking | From | Matt Helsley <> | Date | Fri, 07 Jul 2006 14:11:26 -0700 |
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On Fri, 2006-07-07 at 15:59 -0400, Alan Stern wrote: > On Fri, 7 Jul 2006, Paul E. McKenney wrote:
<snip>
> > So, a fourth possibility -- can a call from start_kernel() invoke some > > function in yours and Matt's code invoke init_srcu_struct() to get a > > statically allocated srcu_struct initialized? Or, if this is part of > > a module, can the module initialization function do this work? > > > > (Hey, I had to ask!) > > That is certainly a viable approach: just force everyone to use dynamic > initialization. Changes to existing code would be relatively few.
Works for me. I've been working on patches for Andrew's multi-chain proposal and I could use an init function there anyway. Should be faster too -- dynamically-allocated per-cpu memory can take advantage of node-local memory whereas, to my knowledge, statically-allocated cannot.
> I'm not sure where the right place would be to add these initialization > calls. After kmalloc is working but before the relevant notifier chains > get used at all. Is there such a place? I guess it depends on which > notifier chains we convert. > > We might want to leave some chains using the existing rw-semaphore API. > It's more appropriate when there's a high frequency of write-locking > (i.e., things registering or unregistering on the notifier chain). The > SRCU approach is more appropriate when the chain is called a lot and > needs to have low overhead, but (un)registration is uncommon. Matt's task > notifiers are a good example.
Yes, it is an excellent example.
> Alan Stern
Cheers, -Matt Helsley
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