[Xen-users] Guest disk (LVM on SSD) too slow. Xen unstable, DomU-win XP sp2

["biwebco.com" <info@xxxxxxxxxxx>]

nice time, Xen community.

my DomU has very slow Disk performance, despite the usage of SSD's. Maybe somebody can give some good tips to accelerate, or point out my mistakes.

DomU CristalDiskMark 3.0.1 test(roundet):
seq (R/W)   :71 / 86 MB/s
512k(R/W)   :76 / 80 MB/s
4K(R/W)     :4  / 3 MB/s
4K QD32(R/W):4  / 4 MB/s

The same guest running in KVM-Qemu (standard installed on Ubuntu 12.04) has:
seq (R/W)   :319 / 146 MB/s
512k(R/W)   :306 / 143 MB/s
4K(R/W)     :10  / 7 MB/s
4K QD32(R/W):12  / 9 MB/s


Need only Xen because of second graphic card pass through (here works fine)..
 
I have:
intel e5-1620, 64 GB uDDR @1333Mgz, Dom0 on SSD OCZ Vertex4(@SATA3 port). Second SSD OCZ Agility 3 (@SATA3 port) with LVM 2 only for DomU.
Kernel (3.4.7) + Xen unstable(rev 25705, Aug 02 14:44:53 2012 +0100) self compiled (according to Manual of Teo En Ming)
DimU: Windows XP sp 2

# lvdisplay
File descriptor 8 (pipe:[16062]) leaked on lvdisplay invocation. Parent PID 4821: bash
  --- Logical volume ---
  LV Name                /dev/SSDagility/win_xp
  VG Name                SSDagility
  LV UUID                IsYry9-rirf-G7oW-WSVC-fUOI-0VV1-TnQcIA
  LV Write Access        read/write
  LV Status              available
  # open                 2
  LV Size                58,59 GiB
  Current LE             15000
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           252:0
....

--------------------------DomU configuration file------------------------
name = "winxp"
#kernel = "/usr/lib/xen/boot/hvmloader"
firmware_override = "/usr/lib/xen/boot/hvmloader"

builder='hvm'
#device_model_stubdomain_override = 1
#device_model='qemu-dm'
#device_model='stubdom'
#device_model='stubdom-dm'
#device_model='qemu-xen'

memory = 3096
vcpus=4
boot='cd'

disk = [ 'phy:/dev/SSDagility/win_xp,sda,rw', 'file:/home/looser/Downloads/wind_xp.iso,hdb:cdrom,r']


on_reboot   = 'restart'
on_crash    = 'restart'
keymap = "de"

sdl=1
stdvga=1

serial='pty'
pci = ['04:00.0', '04:00.1']
pci_power_mgmt=1
pci_msitranslate=1
xen_platform_pci=1
viridian=1

#High Precision Event Timer
hpet=1

pae=0
#Advanced Configuration and Power Interface
acpi=1
#Advanced Programmable Interrupt Controller
apic=1
gfx_passthru=0
--------------------------END DomU config ------------------------

to start DomU I do: xl -f create winxp

in DomU, Windows detected IDE-Controller: Intel 82371SB-PCI-Bus-Master-IDE-Controller
HDD detected: QEMU HARDDISK (disabling write cache don't work, after reboot it will be automatically activated back)


For good and functioning tip and I'm buying beer :)

Best thanks.
Denis.
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