Il 13/02/2014 10:11, Alex Bligh ha scritto:
Mike,
On 12 Feb 2014, at 19:09, Mike Day wrote:
Allow readers to use RCU when reading Qemu timer lists. Applies to
Paolo Bonzini's RCU branch, https://github.com/bonzini/qemu/tree/rcu.
This patch is for comment and review only. The rcu branch needs to be
rebased on upstream.
I'll certainly have a look through this. However before I do, what
problem is this trying to solve? Do we think there is possibility
of contention on the active timers lock? I used to think this was
taken (let alone contented) relatively infrequently, but Rob Herring's
recent email suggests to me the list is being modified in some
circumstances rather more frequently than I thought.
I think that, more than contention, it tries to reduce the cost of
synchronization primitives, especially the locking and unlocking of the
list around the invocation of timer callbacks.
Paolo
