Re: [PATCH tip/core/rcu 06/17] rcu: Eliminate read-modify-write ACCESS_ONCE() calls

2014-07-08 Thread Paul E. McKenney
On Tue, Jul 08, 2014 at 04:43:37PM -0400, Pranith Kumar wrote: > On Tue, Jul 8, 2014 at 4:35 PM, Paul E. McKenney > wrote: > > > > Good catch, I clearly didn't include enough patterns in my search. > > > > But please see below. And please rebase onto branch rcu/dev in > > git://git.kernel.org/pub

Re: [PATCH tip/core/rcu 06/17] rcu: Eliminate read-modify-write ACCESS_ONCE() calls

2014-07-08 Thread Pranith Kumar
On Tue, Jul 8, 2014 at 4:35 PM, Paul E. McKenney wrote: > > Good catch, I clearly didn't include enough patterns in my search. > > But please see below. And please rebase onto branch rcu/dev in > git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git, > as this patch set does not app

Re: [PATCH tip/core/rcu 06/17] rcu: Eliminate read-modify-write ACCESS_ONCE() calls

2014-07-08 Thread Paul E. McKenney
On Tue, Jul 08, 2014 at 12:59:46PM -0400, Pranith Kumar wrote: > Hi Paul, > > On Mon, Jul 7, 2014 at 6:38 PM, Paul E. McKenney > wrote: > > From: "Paul E. McKenney" > > > > RCU contains code of the following forms: > > > > ACCESS_ONCE(x)++; > > ACCESS_ONCE(x) += y; > > AC

Re: [PATCH tip/core/rcu 06/17] rcu: Eliminate read-modify-write ACCESS_ONCE() calls

2014-07-08 Thread Pranith Kumar
Hi Paul, On Mon, Jul 7, 2014 at 6:38 PM, Paul E. McKenney wrote: > From: "Paul E. McKenney" > > RCU contains code of the following forms: > > ACCESS_ONCE(x)++; > ACCESS_ONCE(x) += y; > ACCESS_ONCE(x) -= y; > > Now these constructs do operate correctly, but they really res

[PATCH tip/core/rcu 06/17] rcu: Eliminate read-modify-write ACCESS_ONCE() calls

2014-07-07 Thread Paul E. McKenney
From: "Paul E. McKenney" RCU contains code of the following forms: ACCESS_ONCE(x)++; ACCESS_ONCE(x) += y; ACCESS_ONCE(x) -= y; Now these constructs do operate correctly, but they really result in a pair of volatile accesses, one to do the load and another to do the store