Messages in this thread | | | Subject | Re: [PATCH v2] rwsem: Support optimistic spinning | From | Davidlohr Bueso <> | Date | Wed, 30 Apr 2014 09:32:17 -0700 |
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On Wed, 2014-04-30 at 11:21 +0200, Peter Zijlstra wrote: > On Mon, Apr 28, 2014 at 03:09:01PM -0700, Davidlohr Bueso wrote: > > +#ifdef CONFIG_SMP > > > +#else > > +static bool rwsem_optimistic_spin(struct rw_semaphore *sem) > > +{ > > + return false; > > +} > > +#endif > > On the mutex side we guard this with MUTEX_SPIN_ON_OWNER, do we want to > use that here too?
I thought of it, but hated adding mutex naming to rwsem code -- we already do it for cpu_relax() thanks to s390.
MUTEX_SPIN_ON_OWNER depends on SMP && !DEBUG_MUTEXES. Right now rwsem optimistic spinning depends on SMP && RWSEM_XCHGADD_ALGORITHM.
It might sense to add RWSEM_SPIN_ON_OWNER to encapsulate what we already have. I don't think we want DEBUG_MUTEX dependencies in rwsems. Would you accept such thing?
Thanks, Davidlohr
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