On 12/10/2014 12:06 PM, Marcelo Tosatti wrote: > For the hrtimer which emulates the tscdeadline timer in the guest, > add an option to advance expiration, and busy spin on VM-entry waiting > for the actual expiration time to elapse. > > This allows achieving low latencies in cyclictest (or any scenario > which requires strict timing regarding timer expiration). > > Reduces cyclictest avg latency by 50%. > > Note: this option requires tuning to find the appropriate value > for a particular hardware/guest combination. One method is to measure the > average delay between apic_timer_fn and VM-entry. > Another method is to start with 1000ns, and increase the value > in say 500ns increments until avg cyclictest numbers stop decreasing. It would be good to document how this is used, in the changelog. -- 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
