From mboxrd@z Thu Jan  1 00:00:00 1970
From: Hollis Blanchard <hollisb@us.ibm.com>
Subject: Re: [kvm-devel] Use virtual cpu accounting if available for guest
	times.
Date: Fri, 19 Oct 2007 11:57:36 -0500
Message-ID: <1192813056.10451.6.camel@basalt>
References: <47135D1B.1060004@bull.net>
	 <11926264852739-git-send-email-Laurent.Vivier@bull.net>
	 <200710181439.10390.borntraeger@de.ibm.com>
Reply-To: Hollis Blanchard <hollisb@us.ibm.com>
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Cc: Avi Kivity <avi@qumranet.com>,
	kvm-devel <kvm-devel@lists.sourceforge.net>,
	Laurent Vivier <Laurent.Vivier@bull.net>,
	linux-kernel@vger.kernel.org
To: Christian Borntraeger <borntraeger@de.ibm.com>
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List-Id: kvm.vger.kernel.org

On Thu, 2007-10-18 at 14:39 +0200, Christian Borntraeger wrote:
> Avi,
> 
> ppc and s390 offer the possibility to track process times precisely
> by looking at cpu timer on every context switch, irq, softirq etc.
> We can use that infrastructure as well for guest time accounting.
> We need to account the used time before we change the state. 
> This patch adds a call to account_system_vtime to kvm_guest_enter
> and kvm_guest exit. If CONFIG_VIRT_CPU_ACCOUNTING is not set,
> account_system_vtime is defined in hardirq.h as an empty function,
> which means this patch does not change the behaviour on other
> platforms.
> 
> I compile tested this patch on x86 and function tested the patch on
> s390.
> 
> Avi, please apply.
> 
> 
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> 
> ---
>  drivers/kvm/kvm.h |    3 +++
>  1 file changed, 3 insertions(+)
> 
> Index: kvm/drivers/kvm/kvm.h
> ===================================================================
> --- kvm.orig/drivers/kvm/kvm.h
> +++ kvm/drivers/kvm/kvm.h
> @@ -7,6 +7,7 @@
>   */
> 
>  #include <linux/types.h>
> +#include <linux/hardirq.h>
>  #include <linux/list.h>
>  #include <linux/mutex.h>
>  #include <linux/spinlock.h>
> @@ -669,11 +670,13 @@ __init void kvm_arch_init(void);
> 
>  static inline void kvm_guest_enter(void)
>  {
> +	account_system_vtime(current);
>  	current->flags |= PF_VCPU;
>  }
> 
>  static inline void kvm_guest_exit(void)
>  {
> +	account_system_vtime(current);
>  	current->flags &= ~PF_VCPU;
>  }

I don't understand. Should kvm_guest_exit() be calling
account_user_vtime() (instead of account_system_vtime())?

-- 
Hollis Blanchard
IBM Linux Technology Center