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[Xen-users] GPL PV: Performance issues with Xen 3.1.0 and xp64.

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] GPL PV: Performance issues with Xen 3.1.0 and xp64.
From: Juan Pablo Rojas Jiménez <jprojas@xxxxxxxxxxxxxxx>
Date: Tue, 26 Aug 2008 18:34:12 +0200
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Hi all,

I've been playing around quite a bit with xen, windows and the GPL PV drivers... My setup is an opensuse 10.3 (xen 3.1) with two dual core Opteron and a raid5 (md)/ LVM setup used for domU block devices.

My problem/issue here is that, when enabling the GPL PV drivers ( /gplpv option ), everything seems to work fine (all pv devices get enabled, qemu devices get hidden and so), but the IO performance is much more slow than through the default qemu setup.

Usually, the raid+lvm setup give's me a 30 MB/s sustained write performance... from the xp64 domU under qemu i get around 13MB/s (i'm using a tool called disktt that uses windows system calls to write a file of a certain size), and enabling /gplpv the speed goes down until 4MB/s or less.

Other thing i've seen is that qemu with an xp32 is also in the 3-4MB/s' when writing.

I've tried changing the vm config from hda to xvda but the vm doesn't boot , changing windows 'optimization' options in the device, formating from the guest domU with different block sizes (just to try), and i get no performance gain's when enabling gplpv. Tried with tap:aio devices created under a lvm supported filesystem, ...

Does anybody know if there's some trick i've missed in the vm configuration or maybe the dom0 ? I don't know what else to try :(

Here you have the vm config file for xp64, so you can check if i've something wrong.

-------------------------------------------
name="xp64sp2.base"
ostype="windowsxp"
uuid="5672033b-f819-b3a8-26fe-8876743c5112"
memory=512
vcpus=2
cpus = "2,3"
on_crash="destroy"
on_poweroff="destroy"
on_reboot="restart"
localtime=1

builder="hvm"
extid=0
device_model="/usr/lib64/xen/bin/qemu-dm"
kernel="/usr/lib/xen/boot/hvmloader"
extra=" clocksource=jiffies "
boot="c"
disk=[
       'phy:/dev/vg_md1/lv_xen_xp64sp2_base,hda,w',
#       'file:/admin/ooss/xp64sp2/xp64sp2.iso,hdc:cdrom,r',
]
#vif=[ 'mac=00:16:3e:26:00:26,model=rtl8139,bridge=xenbr0', ]
vif=['mac=00:16:3e:26:00:26',]
vfb=['type=vnc,vncdisplay=26,vnclisten=0.0.0.0,vncpasswd=vncadmin,display=0',]
stdvga=0
vnc=1
vncunused=1
apic=1
acpi=1
pae=1
usb=1
usbdevice='tablet'
serial="pty"
-----------------------------------------------

Thank so much, and congrats for the great job,

Juan Pablo

Attachment: jprojas.vcf
Description: Vcard

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