On 16/2/07 08:37, "Dan Hecht" <dhecht at vmware.com> wrote: > Hmm? I thought the periodic timer and one-shot timer both generate the > same VIRQ. So, how can you mask one without masking the other? > > The tickless idle works since the block hypercall disables the periodic > timer. But for dynticks (aka NO_HZ), you'll need to mask the periodic > timer (even for a running vcpu), while keeping the one-shot timer > unmasked. I don't think Xen provides an interface to do that. There's no interface for this right now, but we can easily add one in a backward compatible way. This also will not prevent a dyntick kernel from running on an older Xen -- the guest will then receive to many timer interrupts, but that should only be a performance concern fixable by upgrading the hypervisor component of the system. -- Keir
