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SubjectRe: [Xen-devel] [PATCH RFC v2 4/4] xen/arm: account for stolen ticks
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On Mon, 2013-05-06 at 15:51 +0100, Stefano Stabellini wrote:
> Register the runstate_memory_area with the hypervisor.
> Use pv_time_ops.steal_clock to account for stolen ticks.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> ---
> arch/arm/xen/enlighten.c | 23 +++++++++++++++++++++++
> 1 files changed, 23 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> index ee86bfa..2a5cc82 100644
> --- a/arch/arm/xen/enlighten.c
> +++ b/arch/arm/xen/enlighten.c
> @@ -14,7 +14,10 @@
> #include <xen/xen-ops.h>
> #include <asm/xen/hypervisor.h>
> #include <asm/xen/hypercall.h>
> +#include <asm/arch_timer.h>
> #include <asm/system_misc.h>
> +#include <asm/paravirt.h>
> +#include <linux/jump_label.h>
> #include <linux/interrupt.h>
> #include <linux/irqreturn.h>
> #include <linux/module.h>
> @@ -152,6 +155,20 @@ int xen_unmap_domain_mfn_range(struct vm_area_struct *vma,
> }
> EXPORT_SYMBOL_GPL(xen_unmap_domain_mfn_range);
>
> +unsigned long long xen_stolen_accounting(int cpu)
> +{
> + struct vcpu_runstate_info state;
> +
> + if (cpu != get_cpu())

get_cpu disables preempt, so you need a matching put_cpu.

But actually I think you just want smp_processor_id and you probably
want the BUG_ON form to get unlikely etc.

That said, you don't use cpu for anything else, so why not drop it
entirely?

> + BUG();
> +
> + xen_get_runstate_snapshot(&state);
> +
> + WARN_ON(state.state != RUNSTATE_running);
> +
> + return state.time[RUNSTATE_runnable] + state.time[RUNSTATE_offline];
> +}
> +
> static void __init xen_percpu_init(void *unused)
> {
> struct vcpu_register_vcpu_info info;
> @@ -170,6 +187,8 @@ static void __init xen_percpu_init(void *unused)
> BUG();
> per_cpu(xen_vcpu, cpu) = vcpup;
>
> + xen_setup_runstate_info(cpu);
> +
> enable_percpu_irq(xen_events_irq, 0);
> }
>
> @@ -301,6 +320,10 @@ static int __init xen_init_events(void)
>
> on_each_cpu(xen_percpu_init, NULL, 0);
>
> + pv_time_ops.steal_clock = xen_stolen_accounting;
> + static_key_slow_inc(&paravirt_steal_enabled);
> + static_key_slow_inc(&paravirt_steal_rq_enabled);

We don't seem to do this on x86 -- is that a bug on x86 on Xen?

> +
> return 0;
> }
> postcore_initcall(xen_init_events);




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