Re: Question about VirtIO on Xen - Disk performance issues

[Luca Tongiani <luca.tongiani@sinte.net>]

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Hi,
thanks in advance for your reply :)


I have attached the following email configuration DomU and the output 
you have requested .
Performance disk are all my machines the most serious problem , even if 
they are used powerful hardware .
Differences in Disk writing in DomU are 1/3 of those of the Dom0 .


Thank you in advance Luca







Il 05/01/2016 12:09, Stefano Stabellini ha scritto:
> Could you please post your VM config file and the output of
> xenstore-ls once the VM has completed the boot sequence?
>
> On Tue, 5 Jan 2016, Luca Tongiani wrote:
>> Hi Stefano,
>> im writing to you because im having issue with I/O disk in my DomU With Xen (Gentoo based system).
>>
>> I tried to use the driver that you provided for the PV .
>> But the results are still not good , there is no way to support the use of Xen VirtIO disk ? Many thanks in
>> advance
>>
>> Luca
>>
>> Il 12/16/15 12:31, Stefano Stabellini ha scritto:
>>
>> Hello Luca,
>>
>> the recommended way to increase disk performance would be to use Xen PV
>> disks. You just need to install the Windows PV drivers:
>>
>> http://www.xenproject.org/developers/teams/windows-pv-drivers.html
>>
>> But using VirtIO disk should also increase performance, even though
>> most probably not as much.
>>
>> Cheers,
>>
>> Stefano
>>
>> On Tue, 15 Dec 2015, Luca Tongiani wrote:
>>
>> Hi to all,
>> I'm writing you this mail for asking some advice about a great problem i'm havin in running a Windows VM
>> (HVM) onto a Xen (Gentoo based) Hypevisor.
>>
>> I need to achieve maximum performance from this VM because of intense SQL tasks running in it.
>>
>> I've seen good improvement in IO on disk using VirtIO on a Windows VM onto a QEMU (QNAP) hypervisor, and i'm
>> tryin to use this feature also on my Xen HV.
>> Is VirtIO disk a good way to improve performance?
>>
>> Thx in advance and hope to keep in touch
>> --
>>
>> Luca Tongiani
>>
>> Sinte srl
>> Soluzioni Informatiche e Telematiche
>> via Monte Grappa 4/B
>> 20900 Monza (MB)
>>
>> Cel (+39) 339 745 49 21
>> Tel (+39) 039 200 59 60
>> Fax (+39) 039 200 69 42
>> Web www.sinte.net
>>
>>
>>
>>
>> --
>>
>> Luca Tongiani
>>
>> Sinte srl
>> Soluzioni Informatiche e Telematiche
>> via Monte Grappa 4/B
>> 20900 Monza (MB)
>>
>> Tel (+39) 039 200 59 60
>> Fax (+39) 039 200 69 42
>> Web www.sinte.net
>>
>>
>>

-- 

*Luca Tongiani*

*Sinte* srl
Soluzioni Informatiche e Telematiche
via Monte Grappa 4/B
20900 Monza (MB)

*Tel* (+39) 039 200 59 60
*Fax* (+39) 039 200 69 42
*Web* www.sinte.net <http://www.sinte.net/>


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[-- Attachment #2: xenstore-ls_output_backupvm --]
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 00000000-0000-0000-0000-000000000000-25 = ""
  on_xend_stop = "ignore"
  pool_name = "Pool-0"
  shadow_memory = "0"
  uuid = "00000000-0000-0000-0000-000000000000"
  on_reboot = "restart"
  image = "(linux (kernel '') (superpages 0) (nomigrate 0) (tsc_mode 0))"
   ostype = "linux"
   kernel = ""
   cmdline = ""
   ramdisk = ""
  on_poweroff = "destroy"
  bootloader_args = ""
  on_xend_start = "ignore"
  on_crash = "restart"
  xend = ""
   restart_count = "0"
  vcpus = "2"
  vcpu_avail = "3"
  bootloader = ""
  name = "Domain-0"
 6d2e6572-6316-8527-1bc3-7a32b7fdd35f = ""
  image = "(linux (kernel /var/xen/boot/vmlinuz-2.6.38-gentoo-r6) (args 'roo\..."
   ostype = "linux"
   kernel = "/var/xen/boot/vmlinuz-2.6.38-gentoo-r6"
   cmdline = "root=/dev/xvda1 xencons=hvc0"
   ramdisk = ""
  device = ""
   tap = ""
    51713 = ""
     frontend = "/local/domain/5/device/vbd/51713"
     frontend-id = "5"
     backend-id = "0"
     backend = "/local/domain/0/backend/tap/5/51713"
    51715 = ""
     frontend = "/local/domain/5/device/vbd/51715"
     frontend-id = "5"
     backend-id = "0"
     backend = "/local/domain/0/backend/tap/5/51715"
   vbd = ""
    51714 = ""
     frontend = "/local/domain/5/device/vbd/51714"
     frontend-id = "5"
     backend-id = "0"
     backend = "/local/domain/0/backend/vbd/5/51714"
   vif = ""
    0 = ""
     frontend = "/local/domain/5/device/vif/0"
     frontend-id = "5"
     backend-id = "0"
     backend = "/local/domain/0/backend/vif/5/0"
   console = ""
    0 = ""
     frontend = "/local/domain/5/device/console/0"
     frontend-id = "5"
     backend-id = "0"
     backend = "/local/domain/0/backend/console/5/0"
  on_xend_stop = "ignore"
  pool_name = "Pool-0"
  shadow_memory = "0"
  uuid = "6d2e6572-6316-8527-1bc3-7a32b7fdd35f"
  on_reboot = "restart"
  start_time = "1343314858.24"
  on_poweroff = "destroy"
  bootloader_args = ""
  on_xend_start = "ignore"
  on_crash = "restart"
  xend = ""
   restart_count = "0"
  vcpus = "1"
  vcpu_avail = "1"
  bootloader = ""
  name = "bmsbackup"

[-- Attachment #3: conf_DomU_Xen --]
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 #  -*- mode: python; -*-
#============================================================================
# Python configuration setup for 'xm create'.
# This script sets the parameters used when a domain is created using 'xm create'.
# You use a separate script for each domain you want to create, or 
# you can set the parameters for the domain on the xm command line.
#============================================================================

#----------------------------------------------------------------------------
# Kernel image file.
#kernel = "/var/xen/boot/vmlinuz-2.6.32-gentoo-r7"
#kernel = "/var/xen/boot/vmlinuz-2.6.34-xen"
#kernel = "/var/xen/boot/vmlinuz-2.6.38-gentoo-r6"
kernel = "/var/xen/boot/vmlinuz-4.0.5-gentoo_bmsbackup"                                                                                                                 
                                                                                                                                                                        
                                                                                                                                                                        

# Optional ramdisk.
#ramdisk = "/boot/initrd.gz"

# The domain build function. Default is 'linux'.
#builder='linux'

# Initial memory allocation (in megabytes) for the new domain.
#
# WARNING: Creating a domain with insufficient memory may cause out of
#          memory errors. The domain needs enough memory to boot kernel
#          and modules. Allocating less than 32MBs is not recommended.
memory = 2048

# A name for your domain. All domains must have different names.
name = "bmsbackup"

# 128-bit UUID for the domain.  The default behavior is to generate a new UUID
# on each call to 'xm create'.
#uuid = "06ed00fe-1162-4fc4-b5d8-11993ee4a8b9"

# List of which CPUS this domain is allowed to use, default Xen picks
#cpus = ""         # leave to Xen to pick
#cpus = "0"        # all vcpus run on CPU0
#cpus = "0-3,5,^1" # all vcpus run on cpus 0,2,3,5
#cpus = ["2", "3"] # VCPU0 runs on CPU2, VCPU1 runs on CPU3
cpus = "1"

# Number of Virtual CPUS to use, default is 1
vcpus = 1

#----------------------------------------------------------------------------
# Define network interfaces.

# By default, no network interfaces are configured.  You may have one created
# with sensible defaults using an empty vif clause:
#
# vif = [ '' ]
#
# or optionally override backend, bridge, ip, mac, script, type, or vifname:
#
# vif = [ 'mac=00:16:3e:00:00:11, bridge=xenbr0' ]
#
# or more than one interface may be configured:
#
# vif = [ '', 'bridge=xenbr1' ]

vif = [ 'bridge=xenbr0' ]

#----------------------------------------------------------------------------
# Define the disk devices you want the domain to have access to, and
# what you want them accessible as.
# Each disk entry is of the form phy:UNAME,DEV,MODE
# where UNAME is the device, DEV is the device name the domain will see,
# and MODE is r for read-only, w for read-write.

#disk = [ 'tap:aio:/var/xen/mailserver.img,xvda1,w', 'phy:/dev/drbd1,xvda2,w' ]
disk = [ 'tap:aio:/var/xen/bmsbackup_new.img,xvda1,w', 'phy:/dev/vm/dati,xvda2,w', 'tap:aio:/var/xen/bmsbackup.swap,xvda3,w' ]

#----------------------------------------------------------------------------
# Define frame buffer device.
#
# By default, no frame buffer device is configured.
#
# To create one using the SDL backend and sensible defaults:
#
# vfb = [ 'sdl=1' ]
#
# This uses environment variables XAUTHORITY and DISPLAY.  You
# can override that:
#
# vfb = [ 'sdl=1,xauthority=/home/bozo/.Xauthority,display=:1' ]
#
# To create one using the VNC backend and sensible defaults:
#

#vfb = [ 'vnc=1' ]

vnc=1

#
# The backend listens on 127.0.0.1 port 5900+N by default, where N is
# the domain ID.  You can override both address and N:
#
# vfb = [ 'vnc=1,vnclisten=127.0.0.1,vncdisplay=1' ]
#
# Or you can bind the first unused port above 5900:
#

# vfb = [ 'vnc=1,vnclisten=0.0.0.0,vncunused=1' ]

#
# You can override the password:
#
# vfb = [ 'vnc=1,vncpasswd=MYPASSWD' ]
#
# Empty password disables authentication.  Defaults to the vncpasswd
# configured in xend-config.sxp.

#----------------------------------------------------------------------------
# Define to which TPM instance the user domain should communicate.
# The vtpm entry is of the form 'instance=INSTANCE,backend=DOM'
# where INSTANCE indicates the instance number of the TPM the VM
# should be talking to and DOM provides the domain where the backend
# is located.
# Note that no two virtual machines should try to connect to the same
# TPM instance. The handling of all TPM instances does require
# some management effort in so far that VM configration files (and thus
# a VM) should be associated with a TPM instance throughout the lifetime
# of the VM / VM configuration file. The instance number must be
# greater or equal to 1.
#vtpm = [ 'instance=1,backend=0' ]

#----------------------------------------------------------------------------
# Set the kernel command line for the new domain.
# You only need to define the IP parameters and hostname if the domain's
# IP config doesn't, e.g. in ifcfg-eth0 or via DHCP.
# You can use 'extra' to set the runlevel and custom environment
# variables used by custom rc scripts (e.g. VMID=, usr= ).

# Set if you want dhcp to allocate the IP address.
#dhcp="dhcp"
# Set netmask.
#netmask=
# Set default gateway.
#gateway=
# Set the hostname.
#hostname= "vm%d" % vmid


# Set root device.
root = "/dev/xvda1"
console = "hvc0"

# Root device for nfs.
#root = "/dev/nfs"
# The nfs server.
#nfs_server = '192.0.2.1'  
# Root directory on the nfs server.
#nfs_root   = '/full/path/to/root/directory'

# Sets runlevel 4.
#extra = "4"
extra = "xencons=hvc0"

#----------------------------------------------------------------------------
# Configure the behaviour when a domain exits.  There are three 'reasons'
# for a domain to stop: poweroff, reboot, and crash.  For each of these you
# may specify:
#
#   "destroy",        meaning that the domain is cleaned up as normal;
#   "restart",        meaning that a new domain is started in place of the old
#                     one;
#   "preserve",       meaning that no clean-up is done until the domain is
#                     manually destroyed (using xm destroy, for example); or
#   "rename-restart", meaning that the old domain is not cleaned up, but is
#                     renamed and a new domain started in its place.
#
# In the event a domain stops due to a crash, you have the additional options:
#
#   "coredump-destroy", meaning dump the crashed domain's core and then destroy;
#   "coredump-restart', meaning dump the crashed domain's core and the restart.
#
# The default is
#
#   on_poweroff = 'destroy'
#   on_reboot   = 'restart'
#   on_crash    = 'restart'
#
# For backwards compatibility we also support the deprecated option restart
#
# restart = 'onreboot' means on_poweroff = 'destroy'
#                            on_reboot   = 'restart'
#                            on_crash    = 'destroy'
#
# restart = 'always'   means on_poweroff = 'restart'
#                            on_reboot   = 'restart'
#                            on_crash    = 'restart'
#
# restart = 'never'    means on_poweroff = 'destroy'
#                            on_reboot   = 'destroy'
#                            on_crash    = 'destroy'

#on_poweroff = 'destroy'
#on_reboot   = 'restart'
#on_crash    = 'restart'

#-----------------------------------------------------------------------------
#   Configure PVSCSI devices:
#
#vscsi=[ 'PDEV, VDEV' ]
#
#   PDEV   gives physical SCSI device to be attached to specified guest
#          domain by one of the following identifier format.
#          - XX:XX:XX:XX (4-tuples with decimal notation which shows
#                          "host:channel:target:lun")
#          - /dev/sdxx or sdx
#          - /dev/stxx or stx
#          - /dev/sgxx or sgx
#          - result of 'scsi_id -gu -s'.
#            ex. # scsi_id -gu -s /block/sdb
#                  36000b5d0006a0000006a0257004c0000
#
#   VDEV   gives virtual SCSI device by 4-tuples (XX:XX:XX:XX) as 
#          which the specified guest domain recognize.
#

#vscsi = [ '/dev/sdx, 0:0:0:0' ]

#============================================================================

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