On Thu, Apr 20, 2017 at 02:00:58PM +0200, Paolo Bonzini wrote:
> I'm not trying too hard yet.  Later, with multiqueue support,
> this may cause cacheline bouncing.

This patch calls qemu_clock_get_ns() within a spinlock region.  It's
probably just a memory load, rdtsc, and some math but more heavy-weight
code paths are possible too.

Taking the clock reading outside the lock region should be fine and
reduces the chance of contention.