Messages in this thread |  | | | Date | Wed, 14 Dec 2005 02:12:53 +0100 | | From | Andi Kleen <> | | Subject | Re: Semantics of smp_mb() [was : Re: [PATCH] Fix RCU race in access of nohz_cpu_mask ] |
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On Tue, Dec 13, 2005 at 02:50:59PM -0800, Paul E. McKenney wrote: > On Wed, Dec 14, 2005 at 09:27:41AM +1100, Keith Owens wrote: > > On Tue, 13 Dec 2005 08:20:27 -0800, > > "Paul E. McKenney" <paulmck@us.ibm.com> wrote: > > >If the variable p references MMIO rather than normal memory, then > > >wmb() and rmb() are needed instead of smp_wmb() and smp_rmb(). > > > > mmiowb(), not wmb(). IA64 has a different form of memory fence for I/O > > space compared to normal memory. MIPS also has a non-empty form of > > mmiowb(). > > New one on me!
Didn't it make only a difference on the Altix or something like that? I suppose they added it only on the drivers for devices supported by SGI.
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