From 6cb9a8350aee789100a365794272ed20cc8f2401 Mon Sep 17 00:00:00 2001 From: Zachary Amsden Date: Mon, 5 Mar 2007 00:30:35 -0800 Subject: [PATCH] vmi: sched clock paravirt op fix The custom_sched_clock hook is broken. The result from sched_clock needs to be in nanoseconds, not in CPU cycles. The TSC is insufficient for this purpose, because TSC is poorly defined in a virtual environment, and mostly represents real world time instead of scheduled process time (which can be interrupted without notice when a virtual machine is descheduled). To make the scheduler consistent, we must expose a different nature of time, that is scheduled time. So deprecate this custom_sched_clock hack and turn it into a paravirt-op, as it should have been all along. This allows the tsc.c code which converts cycles to nanoseconds to be shared by all paravirt-ops backends. It is unfortunate to add a new paravirt-op, but this is a very distinct abstraction which is clearly different for all virtual machine implementations, and it gets rid of an ugly indirect function which I ashamedly admit I hacked in to try to get this to work earlier, and then even got in the wrong units. Signed-off-by: Zachary Amsden Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-i386/vmi_time.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/asm-i386/vmi_time.h') diff --git a/include/asm-i386/vmi_time.h b/include/asm-i386/vmi_time.h index c1293121100..f59c35d3735 100644 --- a/include/asm-i386/vmi_time.h +++ b/include/asm-i386/vmi_time.h @@ -49,7 +49,7 @@ extern struct vmi_timer_ops { extern void __init vmi_time_init(void); extern unsigned long vmi_get_wallclock(void); extern int vmi_set_wallclock(unsigned long now); -extern unsigned long long vmi_sched_clock(void); +extern unsigned long long vmi_get_sched_cycles(void); #ifdef CONFIG_X86_LOCAL_APIC extern void __init vmi_timer_setup_boot_alarm(void); -- cgit v1.2.3-70-g09d2