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authorZachary Amsden <zach@vmware.com>2007-03-05 00:30:35 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-03-05 07:57:52 -0800
commit6cb9a8350aee789100a365794272ed20cc8f2401 (patch)
treec2e319b30ebcb6c9d247382303f7fcff1ab0d641 /include/asm-i386/vmi_time.h
parent7507ba34e827ca3c6bbcd34d20a8df8ba365fca6 (diff)
[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 <zach@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/asm-i386/vmi_time.h')
-rw-r--r--include/asm-i386/vmi_time.h2
1 files changed, 1 insertions, 1 deletions
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);