Re: [PATCH/RFC] replace get_scheduled_cycles with sched_clock paravirt_op

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 14 Mar 2007 12:07:14 -0700 Jeremy Fitzhardinge <jeremy@goop.org> 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'