On Wed, 2017-03-15 at 09:43 +0100, Christoffer Dall wrote: > Yes, I think the key is whether you end up taking a timer interrupt > before or after switchign PF_VCPU. So you can spend X jiffies in the > guest, come back, change PF_VCPU (timer still hasen't expired), and > then > the timer expires immediately afterwards, and the whole block of > jiffies > that are incremented as a result of the timer gets accounted as > kernel > time. > > (Note that jiffies on clocksourced architectures is an arbitrary > number, > which somehow scales according to the clocksource frequency, > depending > on the CONFIG_HZ, so a single timer interrupt can increment jiffies > by > more than 1. > That really should not happen with nohz_full. The housekeeping CPU should get a timer interrupt every jiffy, unless something changed recently that I am not aware of. Frederic, am I totally off base?
