On Wed, 14 Mar 2007 12:07:14 -0700 Jeremy Fitzhardinge [off-list ref] wrote:

Subject: Add a sched_clock paravirt_op

The tsc-based get_scheduled_cycles interface is not a good match for
Xen's runstate accounting, which reports everything in nanoseconds.

This patch replaces this interface with a sched_clock interface, which
matches both Xen and VMI's requirements.

In order to do this, we:
   1. replace get_scheduled_cycles with sched_clock
   2. hoist cycles_2_ns into a common header
   3. update vmi accordingly

One thing to note: because sched_clock is implemented as a weak function in
kernel/sched.c, we must define a real function in order to override this weak
binding.  This means the usual paravirt_ops technique of using an inline
function won't work in this case.

include/asm/paravirt.h: In function 'paravirt_sched_clock':
include/asm/paravirt.h:281: warning: implicit declaration of function 'PVOP_CALL0'
include/asm/paravirt.h:281: error: expected expression before 'unsigned'