From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@qumranet.com>
Subject: Re: [kvm-devel] [PATCH/RFC 3/4,	second shot]Introduce "account_guest_time"
Date: Fri, 17 Aug 2007 15:59:41 +0300
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Cc: kvm-devel <kvm-devel@lists.sourceforge.net>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	virtualization <virtualization@lists.linux-foundation.org>
To: Laurent Vivier <Laurent.Vivier@bull.net>
Return-path: <linux-kernel-owner+glk-linux-kernel-3=40m.gmane.org-S1764361AbXHQM7x@vger.kernel.org>
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List-Id: kvm.vger.kernel.org

Laurent Vivier wrote:
> This is another way to compute guest time... I remove the "account modifiers"
> mechanism and call directly account_guest_time() from account_system_time().
> account_system_time() computes user, system and guest times according value
> accumulated in vtime (a ktime_t) in task_struct by the virtual machine.
>   


> @@ -3246,6 +3277,10 @@
>  	struct rq *rq = this_rq();
>  	cputime64_t tmp;
>  
> +#ifdef CONFIG_GUEST_ACCOUNTING
> +	cputime = account_guest_time(p, cputime);
> +#endif
> +
>  	p->stime = cputime_add(p->stime, cputime);
>  
>  	/* Add system time to cpustat. */


In order to reduce the impact on whatever function this is in (use diff
-p please), you can always have a definition of account_guest_time:

#else

static cputime_t account_guest_time(struct task_struct *p, cputime_t cputime)
{
        return cputime;
}

#endif


This way the #ifdef/#endif is not necessary when calling it.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.