Re: [RFC 2/7] change headers preparing for steal time

[Glauber Costa <glommer@redhat.com>]

On Thu, Aug 26, 2010 at 05:04:02PM -0400, Rik van Riel wrote:
> On 08/26/2010 04:44 PM, Zachary Amsden wrote:
> >On 08/25/2010 11:43 AM, Glauber Costa wrote:
> >>This guest/host common patch prepares infrastructure for
> >>the steal time implementation. Some constants are added,
> >>and a name change happens in pvclock vcpu structure.
> >>
> >>Signed-off-by: Glauber Costa<glommer@redhat.com>
> >>---
> >>arch/x86/include/asm/kvm_para.h | 1 +
> >>arch/x86/include/asm/pvclock-abi.h | 4 +++-
> >>2 files changed, 4 insertions(+), 1 deletions(-)
> >>
> >>diff --git a/arch/x86/include/asm/kvm_para.h
> >>b/arch/x86/include/asm/kvm_para.h
> >>index 05eba5e..1759c81 100644
> >>--- a/arch/x86/include/asm/kvm_para.h
> >>+++ b/arch/x86/include/asm/kvm_para.h
> >>@@ -25,6 +25,7 @@
> >>* in pvclock structure. If no bits are set, all flags are ignored.
> >>*/
> >>#define KVM_FEATURE_CLOCKSOURCE_STABLE_BIT 24
> >>+#define KVM_FEATURE_CLOCKSOURCE_STEAL_BIT 25
> >>
> >>#define MSR_KVM_WALL_CLOCK 0x11
> >>#define MSR_KVM_SYSTEM_TIME 0x12
> >>diff --git a/arch/x86/include/asm/pvclock-abi.h
> >>b/arch/x86/include/asm/pvclock-abi.h
> >>index 35f2d19..417061b 100644
> >>--- a/arch/x86/include/asm/pvclock-abi.h
> >>+++ b/arch/x86/include/asm/pvclock-abi.h
> >>@@ -24,7 +24,7 @@
> >>
> >>struct pvclock_vcpu_time_info {
> >>u32 version;
> >>- u32 pad0;
> >>+ u32 steal_time;
> >>u64 tsc_timestamp;
> >>u64 system_time;
> >>u32 tsc_to_system_mul;
> >>@@ -40,5 +40,7 @@ struct pvclock_wall_clock {
> >>} __attribute__((__packed__));
> >>
> >>#define PVCLOCK_TSC_STABLE_BIT (1<< 0)
> >>+#define PVCLOCK_STEAL_BIT (2<< 0)
> >>+
> >>#endif /* __ASSEMBLY__ */
> >>#endif /* _ASM_X86_PVCLOCK_ABI_H */
> >
> >
> >Will 32 bits be enough?
> 
> Good question.   Reading the rest of the code,
> I suspect it won't be, but Glauber will know
> better.

We are at msec resolution, not nanoseconds.
And I doubt we need more than that, since
we'll later on convert to jiffie granularity.

it gives us enough for about 50 days of steal
time.