Re: [PATCH v2] kvm: Fix accounting of interrupts during guest execution on s390

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Christian Borntraeger wrote:
> Avi pointed out, that my first patch was broken, here is the 2nd try.
> I tested the patch on s390 with CONFIG_VIRT_CPU_ACCOUNTING and on x86_64.
> Seems to work.
>
> Currently the scheduler checks for PF_VCPU to decide if this
> timeslice has to be accounted as guest time. On s390 host 
> interrupts are not disabled during guest execution. This causes
> theses interrupts to be accounted as guest time if
> CONFIG_VIRT_CPU_ACCOUNTING is set.
> Solution is to check if an interrupt triggered account_system_time.
> As the tick is timer interrupt based, we have to subtract
> hardirq_offset.
>
> Avi, Ingo, Laurent, feedback is welcome.
>
> CC: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>
> CC: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
> CC: Laurent Vivier <Laurent.Vivier-6ktuUTfB/bM@public.gmane.org>
> Signed-off-by: Christian Borntraeger <borntraeger-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
> ---
>  kernel/sched.c |    6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> Index: kvm/kernel/sched.c
> ===================================================================
> --- kvm.orig/kernel/sched.c
> +++ kvm/kernel/sched.c
> @@ -3395,10 +3395,8 @@ void account_system_time(struct task_str
>  	struct rq *rq = this_rq();
>  	cputime64_t tmp;
>  
> -	if (p->flags & PF_VCPU) {
> -		account_guest_time(p, cputime);
> -		return;
> -	}
> +	if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0))
> +		return account_guest_time(p, cputime);
>  
>  	p->stime = cputime_add(p->stime, cputime);
>  
>   

What's irq_count()?  Is it defined to ignore the timer tick?  Or is that 
hardirq_offset?

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


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