With this set we finally remove tb_lock. The performance gains
when booting a guest are compelling at low core counts. However,
beyond 8 cores performance doesn't improve due to unrelated
contention--see results in the last patch of the series
("tcg: remove tb_lock").

I have another series that greatly reduces this other contention by
using per-CPU locks instead of the BQL to keep track of a subset
of CPUState. But that series is pretty large so let's deal with
this first.

You can fetch the patches from:
  https://github.com/cota/qemu/tree/tb-lock-removal-redux-v1

Thanks,

		Emilio