On Thu, 2012-07-12 at 11:12 +0300, Avi Kivity wrote: > On 07/12/2012 05:17 AM, Benjamin Herrenschmidt wrote: > >> ARM doesn't have an instruction for cpu_relax(), so it can't intercept > >> it. Given ppc's dislike of overcommit, and the way it implements > >> cpu_relax() by adjusting hw thread priority, I'm guessing it doesn't > >> intercept those either, but I'm copying the ppc people in case I'm > >> wrong. So it's s390 and x86. > > > > No but our spinlocks call __spin_yield() (or __rw_yield) which does > > some paravirt tricks already. > > > > We check if the holder is currently running, and if not, we call the > > H_CONFER hypercall which can be used to "give" our time slice to the > > holder. > > > > Our implementation of H_CONFER in KVM is currently a nop though. > > Okay, so you can join the party. See yield_to() and kvm_vcpu_on_spin(). Thanks ! I'll have a look eventually :-) Cheers, Ben. -- 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
