Messages in this thread | | | Date | Mon, 14 Oct 2013 02:23:55 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH 0/6] Optimize the cpu hotplug locking -v2 |
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On Mon, Oct 14, 2013 at 11:05:08AM +0200, Peter Zijlstra wrote: > On Sat, Oct 12, 2013 at 07:06:56PM +0200, Oleg Nesterov wrote: > > it even disables irqs, so this should always imply rcu_read_lock() with > > any implementation, > > Not so; I could make an RCU implementation that drives the state machine > from rcu_read_unlock(). Such an implementation doesn't need the > interrupt driven poll-state driver we currently have and could thus > subvert that assumption :-) > > Then again, there's a good reason PaulMck didn't pick this > implementation.
True enough, but there really are some out-of-tree RCU implementations that do take this approach and where disabling interrupts would not block preemptible RCU. So please do not rely on this implementation detail. You never know...
> > In fact I do not even understand why getaffinity() doesn't simply > > return ->cpus_allowed, but this is off-topic. > > Yeah, me neither :-(, it always surprises me. But changing it is likely > to break stuff so there we are.
I know that feeling...
Thanx, Paul
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