linux-kernel - Re: [PATCH v4 7/9] KVM-GST: KVM Steal time accounting

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Message-ID: <1309602628.10073.24.camel@twins>
Date:	Sat, 02 Jul 2011 12:30:28 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Glauber Costa <glommer@...hat.com>
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Rik van Riel <riel@...hat.com>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>,
	Avi Kivity <avi@...hat.com>,
	Anthony Liguori <aliguori@...ibm.com>,
	Eric B Munson <emunson@...bm.net>
Subject: Re: [PATCH v4 7/9] KVM-GST: KVM Steal time accounting

On Fri, 2011-07-01 at 17:22 -0400, Glauber Costa wrote:
> @@ -3929,6 +3945,23 @@ void account_process_tick(struct task_struct *p, int user_tick)
>                 return;
>         }
>  
> +#ifdef CONFIG_PARAVIRT
> +       if (static_branch(&paravirt_steal_enabled)) {
> +               u64 steal, st = 0;
> +
> +               steal = paravirt_steal_clock(smp_processor_id());
> +               steal -= this_rq()->prev_steal_time;
> +
> +               st = steal_ticks(steal);
> +               this_rq()->prev_steal_time += st * TICK_NSEC;
> +
> +               if (st) {
> +                       account_steal_time(st);
> +                       return;
> +               }
> +       }
> +#endif
> +
>         if (user_tick)
>                 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
>         else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET)) 

So I was about to send an Ack for this patch, when I noticed that this
will all be dead code when CONFIG_IRQ_TIME_ACCOUNTING &&
sched_clock_irqtime.

I think irqtime_account_process_tick() wants a similar hunk (which
suggests splitting it out into an inline function).
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