On 05/10/2012 10:04 PM, Christoph Lameter wrote: > On Wed, 9 May 2012, Michael S. Tsirkin wrote: > > > kvm needs to update some hypervisor variables atomically > > in a sense that the operation can't be interrupted > > in the middle. However the hypervisor always runs > > on the same CPU so it does not need any memory > > barrier or lock prefix. > > > > Add _local bitops for this purpose: define them > > as non-atomics for x86 and (for now) atomics for > > everyone else. > > Have you tried to use the this_cpu_ops for that purpose? They create the > per cpu atomic instructions that you want without a lock prefix and can > also relocate the per cpu pointer to the correct processor via a > segment register prefix. > > There are no bit operations provided right now but those can either be > improvised using this_cpu_cmpxchg or added. this_cpu_xchg() should be sufficient, since only bit zero has any meaning in our use case (so xchg with zero is equivalent to test_and_clear_bit). -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
