From mboxrd@z Thu Jan  1 00:00:00 1970
From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Subject: Time Skewing on Windows XP
Date: Mon, 11 Mar 2013 23:40:28 -0500
Message-ID: <513EB1BC.9050803@amd.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"; Format="flowed"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: George.Dunlap@eu.citrix.com, Jan Beulich <JBeulich@suse.com>
Cc: "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
List-Id: xen-devel@lists.xenproject.org

Hi,

While I was investigating the following issue on Windows XP (both 32-bit and 64-bit):

* AMD NPT performance regression after c/s 24770:7f79475d3de7
    Reference:http://marc.info/?l=xen-devel&m=135075376805215


On the latest source form xen-unstable, I ran into an issue where the timing on the HVM guests skewing about 2x slower than the actual wall clock time.  This results in the system time slowing down. This is regardless of the cpufreq governor scaling. (I tried with both ondemand and performance).

However, I don't see the same behavior on the Win7 HVM guests. Is this a known issue. I assume that XP and Win7 uses different mechanism for keeping time (e.g. rdtsc vs. HPET)?

Thank you,

Suravee