Messages in this thread | | | Date | Thu, 30 Jul 2015 18:34:27 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH tip/core/rcu 19/19] rcu: Add fastpath bypassing funnel locking |
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On Thu, Jul 30, 2015 at 08:34:52AM -0700, Paul E. McKenney wrote: > On Thu, Jul 30, 2015 at 04:44:55PM +0200, Peter Zijlstra wrote:
> > If the extra read before the cmpxchg() does not hurt, we should do the > > same for mutex and make the above redundant. > > I am pretty sure that different hardware wants it done differently. :-/
I think that most archs won't notice since any RmW includes a load of that variable anyhow. The only case where it can matter is if the RmW is done outside of the normal cache hierarchy -- like on Power, where the ll/sc bypasses the L1.
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