From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1K4geS-0008OZ-4Q
	for qemu-devel@nongnu.org; Fri, 06 Jun 2008 14:27:00 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1K4geR-0008O3-7y
	for qemu-devel@nongnu.org; Fri, 06 Jun 2008 14:26:59 -0400
Received: from [199.232.76.173] (port=39049 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1K4geQ-0008Nq-Nd
	for qemu-devel@nongnu.org; Fri, 06 Jun 2008 14:26:58 -0400
Received: from pelvoux.gotadsl.co.uk ([81.6.248.91]:50253)
	by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32)
	(Exim 4.60) (envelope-from <lists@pelvoux.nildram.co.uk>)
	id 1K4geQ-00035R-Ex
	for qemu-devel@nongnu.org; Fri, 06 Jun 2008 14:26:58 -0400
Received: from localhost ([127.0.0.1] helo=ecrins ident=fozzy)
	by localhost with esmtp (Exim 4.69)
	(envelope-from <lists@pelvoux.nildram.co.uk>) id 1K4gBT-0004Yy-M1
	for qemu-devel@nongnu.org; Fri, 06 Jun 2008 18:57:03 +0100
Date: Fri, 06 Jun 2008 18:57:03 +0100
From: Steve Fosdick <lists@pelvoux.nildram.co.uk>
Message-Id: <1212775023.17383.0@ecrins>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable
Subject: [Qemu-devel] Linux CPU accouting with kqemu
Reply-To: qemu-devel@nongnu.org
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: qemu-devel@nongnu.org

I have noticed that the Linux system CPU usage seems remarkably high=20
when running Windows XP as a guest under qemu/kqemu, but not when=20
running under qemu without kqemu.

Just today I was reading the kqemu API documentation and it occurred to=20
be that from the Linux perspective the user/system CPU times may be=20
backward with kqemu.

Is it perhaps the case that when kqemu has been told to run code in the=20
guest VM (KQEMU_EXEC ioctl) and this is happenning without any=20
exceptions (more likely when the guest is running user-mode code rather=20
than OS code) Linux still sees this as running in the kernel and=20
records it as "system" time but when kqemu returns to qemu (because of=20
an exception) the Linux kernel now sees this as user CPU time when in=20
all likelihood the guest OS is now executing somewhere it it's kernel?

Regards,
Steve.