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From: Christian Borntraeger <borntraeger@de.ibm.com>
To: kvm-devel@lists.sourceforge.net
Cc: "Glauber de Oliveira Costa" <glommer@gmail.com>,
	"laurent.vivier@bull.net" <laurent.vivier@bull.net>,
	Jeremy Fitzhardinge <jeremy@goop.org>,
	John Stoffel <john@stoffel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	virtualization <virtualization@lists.linux-foundation.org>
Subject: Re: [kvm-devel] Réf. : Re: [PATCH 0/4] Virtual Machine Time Accounting
Date: Tue, 21 Aug 2007 10:06:42 +0200	[thread overview]
Message-ID: <200708211006.42938.borntraeger@de.ibm.com> (raw)
In-Reply-To: <5d6222a80708201334q27fc6cbcr7ce6a9d7147437a2@mail.gmail.com>

Am Montag, 20. August 2007 schrieb Glauber de Oliveira Costa:
> Although I don't know KVM to a that deep level, I think it should be
> possible to keep the virtual cpus in different process (or threads),
> and take the accounting time from there. Perfectly possible to know
> the time we spent running (user time), and the time the hypervisor
> spent doing things on our behalf (system time).

I disagree here. First thing, you dont want to have the virtual cpu in a 
different process than the hypervisor control code for that cpu. Otherwise  
communication has to be made via IPC. 
Secondly, Its not qemu/kvm that does the accouting. Its existing userspace 
code like top/snmp agents and clients! etc. that would require additional 
knowledge which thread is guest code.

I personally like the approach Laurent has taken. Maybe it needs some polish 
and maybe we want an account_guest_time function, but in general I think he 
is doing the right thing. 

Christian

WARNING: multiple messages have this Message-ID (diff)
From: Christian Borntraeger <borntraeger-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
To: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Cc: Jeremy Fitzhardinge <jeremy-TSDbQ3PG+2Y@public.gmane.org>,
	John Stoffel <john-HgN6juyGXH5AfugRpC6u6w@public.gmane.org>,
	linux-kernel
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	virtualization
	<virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>
Subject: Re: Réf. : Re: [PATCH 0/4] Virtual Machine Time Accounting
Date: Tue, 21 Aug 2007 10:06:42 +0200	[thread overview]
Message-ID: <200708211006.42938.borntraeger@de.ibm.com> (raw)
In-Reply-To: <5d6222a80708201334q27fc6cbcr7ce6a9d7147437a2-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

Am Montag, 20. August 2007 schrieb Glauber de Oliveira Costa:
> Although I don't know KVM to a that deep level, I think it should be
> possible to keep the virtual cpus in different process (or threads),
> and take the accounting time from there. Perfectly possible to know
> the time we spent running (user time), and the time the hypervisor
> spent doing things on our behalf (system time).

I disagree here. First thing, you dont want to have the virtual cpu in a 
different process than the hypervisor control code for that cpu. Otherwise  
communication has to be made via IPC. 
Secondly, Its not qemu/kvm that does the accouting. Its existing userspace 
code like top/snmp agents and clients! etc. that would require additional 
knowledge which thread is guest code.

I personally like the approach Laurent has taken. Maybe it needs some polish 
and maybe we want an account_guest_time function, but in general I think he 
is doing the right thing. 

Christian

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  parent reply	other threads:[~2007-08-21  8:07 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-20 17:54 Réf. : Re: [PATCH 0/4] Virtual Machine Time Accounting laurent.vivier
2007-08-20 20:34 ` Glauber de Oliveira Costa
2007-08-20 20:34   ` Glauber de Oliveira Costa
2007-08-21  7:45   ` Laurent Vivier
2007-08-21  7:45     ` Laurent Vivier
2007-08-21 17:46     ` Glauber de Oliveira Costa
2007-08-21 17:46       ` Glauber de Oliveira Costa
2007-08-21 17:46     ` Glauber de Oliveira Costa
2007-08-21  7:45   ` Laurent Vivier
2007-08-21  8:06   ` [kvm-devel] " Christian Borntraeger
2007-08-21  8:06   ` Christian Borntraeger [this message]
2007-08-21  8:06     ` Christian Borntraeger
2007-08-21 17:47     ` [kvm-devel] " Glauber de Oliveira Costa
2007-08-21 17:47     ` Glauber de Oliveira Costa
2007-08-21 17:47       ` Glauber de Oliveira Costa
2007-08-20 20:34 ` Glauber de Oliveira Costa

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