Re: [PATCH 12/17] Add helper function get_kernel_ns

Avi Kivity
2010-06-15T08:41:43Z

On 06/15/2010 10:34 AM, Zachary Amsden wrote:
> Add a helper function for the multiple places this is used. Note that it
> must not be called in preemptible context, as that would mean the kernel
> could enter software suspend state, which would cause non-atomic operation
> of the monotonic_to_bootbased computation.
>
> Open question: should the KVM_SET_CLOCK / KVM_GET_CLOCK ioctls use this
> as well? Currently, they are not bootbased (but perhaps should be).
>
> Signed-off-by: Zachary Amsden<zamsden@redhat.com>
> ---
> arch/x86/kvm/x86.c | 26 +++++++++++++-------------
> 1 files changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 703ea43..15c7317 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -915,6 +915,16 @@ static void kvm_get_time_scale(uint32_t scaled_khz, uint32_t base_khz,
> __func__, base_khz, scaled_khz, shift, *pmultiplier);
> }
>
> +static inline u64 get_kernel_ns(void)
> +{
> + struct timespec ts;
> +
> + WARN_ON(preemptible());
> + ktime_get_ts(&ts);
> + monotonic_to_bootbased(&ts);
> + return timespec_to_ns(&ts);
> +}
> +
> static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz);
>
>

Isn't something like this a candidate for the time infrastructure?

--
error compiling committee.c: too many arguments to function