WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] weird hvm performance issue.

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] weird hvm performance issue.
From: "Luke S. Crawford" <lsc@xxxxxxxxx>
Date: Mon, 29 Jan 2007 10:08:52 -0800 (PST)
Delivery-date: Mon, 29 Jan 2007 10:08:32 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx

(I posted this on xen-users last week, and nobody seemed to know what was up. It is time, I suppose then, to dust off the debugger; I was hoping one of you could point me in the correct direction to begin troubleshooting this.)

I'm HVM booting our install-disks (systemimager) here, and I'm spotting some weird performance issues. Our install uses rsync and prints every file as it copies it. I notice that files scroll quickly for a while, then slowly. the slowness continues until I press a button (within xm console) at which point the slowness immediately vanishes.


I watch 'top' in the Dom0 in another window, and I see that when files scroll slowly, qemu-dm uses at most 1% cpu; once I press a key and it moves fast again, qemu-dm uses up to 70% of a CPU. (this is on a box with 4 cores) The correlation is extremely strong; I'm fairly certain it's not just in my head.

The CPU usage of qemu-dm correlates with the speed of the scroll; exiting from the xm console does not appear to effect the cpu usage of qemu-dm- it will drop to 1% after several minutes.

any ideas what is going on here? any ideas how I could debug this further?

my xm config file looks something like this:

kernel = "/usr/lib/xen/boot/hvmloader"
device_model = '/usr/lib64/xen/bin/qemu-dm'
builder='hvm'
memory = 512
shadow_memory = 8
vcpus=1
vif = [ 'type=ioemu, bridge=xenbr0' ]
nographic=1
sdl=0
vnc=0
serial='pty'
name = "VM1-64"
fda='/var/tmp/disk_dev.img'
disk = ['file:/var/tmp/si.iso,hdb:cdrom,w',
'phy:/dev/sda5,hda,w']
boot='da'
on_poweroff = 'destroy'
on_crash    = 'restart'



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

<Prev in Thread] Current Thread [Next in Thread>