On Mon, Jan 20, 2014 at 11:59:39PM +0900, Fernando Luis Vazquez Cao wrote: > (2014/01/20 22:33), Marcelo Tosatti wrote: > >On Mon, Jan 20, 2014 at 11:56:56AM +0200, Nadav Har'El wrote: > >>If KVM_SYSTEM_TIME is not a correct way to get a monotonic paravirtual clock > >>from KVM, is there a correct way? > >Inside a Linux guest? Can use sched_clock(). > > I would like to mention that Linux guests usually do not use sched_clock() > directly. The reason being that the kvm_clock based sched_clock() is not > marked stable (sched_clock_stable is 0), which means that the pair of > wrappers sched_clock_local()/sched_clock_remote() is used instead. Should verify the requirements of sched_clock_cpu() and enable sched_clock_stable in case it fulfills requirements (kvmclock_read can be nondecreasing due to TSC->nanosecond scaling, and not increase for a longer duration with global accumulator, due to cmpxchg). -- 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
