From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC 5/8] change kernel accounting to include steal time
Date: Mon, 30 Aug 2010 18:46:25 +0200
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To: Glauber Costa <glommer@redhat.com>
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On Mon, 2010-08-30 at 12:06 -0400, Glauber Costa wrote:
> This patch proposes a common steal time implementation. When no
> steal time is accounted, we just add a branch to the current
> accounting code, that shouldn't add much overhead.

But why not use alternative code and avoid that conditional
all-together?

>   * Account user cpu time to a process.
>   * @p: the process that the cpu time gets accounted to
> @@ -3169,6 +3179,12 @@ void account_user_time(struct task_struct *p, cputime_t cputime,
>  	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
>  	cputime64_t tmp;
>  
> +	tmp = get_steal_time_from_hypervisor();
> +	if (tmp) {
> +		account_steal_time(tmp);
> +		return;
> +	}
> +
>  	/* Add user time to process. */
>  	p->utime = cputime_add(p->utime, cputime);
>  	p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
> @@ -3234,6 +3250,12 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
>  		return;
>  	}
>  
> +	tmp = get_steal_time_from_hypervisor();
> +	if (tmp) {
> +		account_steal_time(tmp);
> +		return;
> +	}
> +
>  	/* Add system time to process. */
>  	p->stime = cputime_add(p->stime, cputime);
>  	p->stimescaled = cputime_add(p->stimescaled, cputime_scaled);

Why replicate that code and not restructure account_process_tick()?