urns out to be 0, even though this_offset > last_offset. +Added fix From: Toyo Abe The x86_64-mm-monotonic-clock.patch in 2.6.18-rc4-mm2 made a change to the updating of monotonic_base. It now uses cycles_2_ns(). I suggest that a set_cyc2ns_scale() should be done prior to the setup_irq(). Because cycles_2_ns() can be called from the timer ISR right after the irq0 is enabled. Signed-off-by: Toyo Abe Signed-off-by: Dimitri Sivanich Signed-off-by: Andi Kleen