From mboxrd@z Thu Jan 1 00:00:00 1970 From: Erik Rull Subject: kvm-77 Excessive Disk Access causes real time clock hang! Date: Fri, 24 Apr 2009 17:29:57 +0200 Message-ID: <49F1DAF5.2060805@rdsoftware.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from moutng.kundenserver.de ([212.227.126.177]:56763 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751578AbZDXPaA (ORCPT ); Fri, 24 Apr 2009 11:30:00 -0400 Sender: kvm-owner@vger.kernel.org List-ID: Hi all, I'm running kvm-77 and windows xp as guest. When I start the defragmentation of the virtualized drive within the windows guest (well this is not a fine way, but it should work :-)), the real time clock starts hanging - I recognized that because some underlying hardware with own timers began to run out of synchronization. I did some research, took a stopwatch and measured against the system time. During the measurement of ~ 30 seconds I got a difference to the linux time (I just called "watch -n 1 date" which should come from the mainboard system time, doesn't it?) of ~10 seconds! This was the biggest difference I could measure, sometimes it was a little bit less. What's happening here? I reduced the io priority and the guest process priority to a very low one - it didn't help! Oh - I'm running the stuff on an Intel Core2Duo T5600 @ 1.83GHz with 2 Gig of RAM (Windows gets 1.5 Gig), the disk is an SATA with 40 Gigs. Best regards, Erik