----- Original Message -----
Every benchmark out there features KVM as the best virtualisation
technology. Even in the I/O write category. My results with oVirt
are deceiving. So I'm going to explain my test machine, setup and
ask your for advice to find out what's wrong. Any more data you
need please ask for it. I like oVirt mostly because of its
datacentre-aware web manager. But if it gets unusable I would have
to take a look at other systems.
Hardware machine for the host OS
---------------------------------
* Sandy Bridge E
* CPU : Intel Xeon E5-1620 (10 MB Intel Smart Cache)
* Cores / Threads : 4 / 8
* Frecuency : 3.6GHz / 3.8GHz Turbo Boost
* RAM : 64 GB DDR3 ECC
* Hard Disk : 2x 2TB SATA3
* VT technology: Intel VT
Common OS Setup for the host OS
---------------------------------
* 2 hard disks RAIDSoft
Guest OS common setup
---------------------
* 1 socket x 1 core x 1 thread
* 2 GB RAM
* 300 GB Preallocated hard disk
* Virtualmin installed (Just an excuse to have a mysql server)
* Ubuntu 12.04 64bit
Write I/O test
--------------
The write I/O test is not standard one but a custom one. One of our
needs is to create new Mysql INNODB tables. These tables have to be
created in less than php maximum execution time so that some web
installations don't timeout when creating their databases.
DISCLAIMER: If you want to evaluate oVirt don't trust on these times,
please do your own tests.
So the test creates table0 with two ints columns which are then
filled with 100 insert intos. Repeat that for 99 more tables.
Finally drop (delete) all the create tables.
What I run is:
mysql -u root -p -e "drop database test_create_tables"
mysql -u root -p -e "create database test_create_tables"
time mysql -u root -p test_create_tables < test_mysql.sql
I attach test_mysql.sql gzipped just in case anyone is curious.
Note that all the Proxmox tests are: Debian Squeeze + Proxmox (KVM).
It was never used openvz as a virtualisation technology.
Test A - Debian Squeeze + Proxmox (KVM)
-----------------
Description: This is proxmox booting a machine as KVM (not as
openvz). As said before only 1 socket and 1 core.
real 0m9.453s
user 0m0.104s
sys 0m0.076s
Test B - Proxmox (KVM, aio=threads)
----------------------------
Description: Proxmox again. Qemu was run at hand by changing aio
parametre to be aio=threads (as oVirt uses) instead of aio=native.
real 0m9.510s
user 0m0.080s
sys 0m0.096s
Test C - Proxmox (linux-image-virtual kernel installed, aio=threads)
--------
Description: If we install linux-image-virtual kernel inside the
guest machine times are improved a bit.
real 0m8.691s
user 0m0.104s
sys 0m0.080s
Test D - Proxmox (ubuntu, linux-virtual, aio=threads y: -cpu
kvm64,+lahf_lm,+ssse3,-cx16)
-----------
real 0m8.790s
user 0m0.084s
sys 0m0.096s
Test E - Proxmox (ubuntu, linux-virtual, aio=threads y: -cpu
kvm64,+lahf_lm,+ssse3,-cx16 -M pc-01.4)
---------
real 0m8.720s
user 0m0.100s
sys 0m0.080s
Test F - Proxmox (ubuntu, linux-virtual, aio=threads y: -cpu
kvm64,+lahf_lm,+ssse3,-cx16 -M pc-01.4 -rtc
base=2013-02-22T02:26:29,driftfix=slew)
--------
real 0m8.790s
user 0m0.096s
sys 0m0.084s
Test G - Virtualbox
------
Description: Ubuntu 12.04 64bit as a host. This is Virtualbox 4.2
with the extension pack installed. Notice that neither I installed
the guest additions tools in the guest machine nor the
linux-image-virtual kernel.
real 0m36.176s
user 0m0.612s
sys 0m0.468s
Test H - Fedora 17 64bit - oVirt 3.1
-------
Description: This is Fedora 17 64bit oVirt 3.1 being installed in the
Host. Web manager is installed in another machine. SELinux is in
Permissive mode. Virtual machine is run at the same virtual machine
where storage is. The datacenter is setup as "Localhost on host"
type. Linux-image-virtual kernel installed inside the guest machine.
real 0m52.246s
user 0m0.200s
sys 0m0.128s
Test I - Fedora - oVirt 3.1 - vdsmd stopped.
-------
Description: This is Fedora 17 64bit oVirt 3.1 being installed in the
Host. Web manager is installed in another machine. SELinux is in
Permissive mode. Virtual machine is run at the same virtual machine
where storage is. The datacenter is setup as "Localhost on host"
type. Linux-image-virtual kernel installed inside the guest machine.
vdsmd daemon was stopped at the host was stopped just in case it was
the I/O decrease reason.
real 0m45.932s
user 0m0.216s
sys 0m0.100s
Some bits about the test:
* If you're asking, yes, I've repeated the test several times and the
times I give here are representative.
The password was inserted manually when running mysql commands but
that's only 1 to 2 seconds less which doesn't explain the huge
differences between the tests.
* I also tried Fedora 64bit and Centos 64bit as guest systems and the
results were worse.
* I also tried other less powerful machines which work ok with
Virtualbox but have poor I/O write results with oVirt.
* The B-F Proxmox tests were trying to reproduce the oVirt parametres
which might be wrong but nothing triggered the 52 secs of Fedora
test so they were kind of useless.
* At H and I tests (the Fedora ones) if you check top command when
the test is being run you get often from 80% to 90% wa(iting).
Some random questions:
* Is it a problem that sandbridge architecture is being detected as
an Intel Conroe architecture?
* Is there any easy way to test aio=native in oVirt when running
virtual machines just for testing it?
Our testing showed that aio=threads works better for file-based storage (vs. aio=native
for block storage).
* Should I test oVirt 3.2? Is there any improvement in I/O writing?
Probably not, but you should try with oVirt 3.2 nevertheless, for the wealth of other
features that might be useful now or later (direct LUN for example).
* What about Fedora 18? Any improvements in I/O writing or, I
don't
know, the Virtio system?
Probably a newer QEMU and KVM can provide better performance. Did not go through the
complete changelog to verify it.
* Any ovirt-node package for Debian/Ubuntu? The wiki seems like a
draft (
http://www.ovirt.org/Ovirt_build_on_debian/ubuntu).
* Any I/O write consuming package that I should remove from stock
Fedora just before installing it from the web manager?
So... Any idea?
I'd start with comparing the complete QEMU command line between the instances. I
don't think it's only the -cpu that'll affect the performance (unless the test
is CPU bound?). Specifically, what about the cache= setting? We use, for data safety,
cache=none.
Y.
Thank you very much!
P.S.: Thanks to my workmate Sergi which found out the mysql test and
was kind to test some of my setups.
--
--
Adrián Gibanel
I.T. Manager
+34 675 683 301
www.btactic.com
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