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

From: Zachary Amsden
Date: Wed Mar 14 2007 - 16:34:44 EST


Jeremy Fitzhardinge 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.

Acked-by: Zachary Amsden <zach@xxxxxxxxxx>


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