On 06/29/2015 08:25 AM, Narayanan, Krishnaprasad wrote:
Hi Jay,

The MySQL database version on both the VMs share the same version which is "mysql  
Ver 14.14 Distrib 5.5.40, for debian-linux-gnu (x86_64) using readline 6.3". The 
my.cnf settings are the same on both the VMs.

Please see my comment about too many variables changing between environments to make it possible to determine causal relationships between the environment and the performance degradation.

Best,
-jay

Regards,
Krishnaprasad

-----Original Message-----
From: Jay Pipes [mailto:jaypi...@gmail.com]
Sent: Montag, 29. Juni 2015 14:05
To: openstack@lists.openstack.org
Subject: Re: [Openstack] MySQL IO performance

On 06/29/2015 07:19 AM, Narayanan, Krishnaprasad wrote:
Hello all,

I ran tests under the following settings to measure the IO performance
of MySQL database. I used Sysbench as the client workload generator. I
found that the performance of MySQL (both resource utilization and
application) has degraded by more than 50% after switching from
setting
a) to setting b).

Setting a): Controller & Compute node OS - Ubuntu 12.04, cloud software:
OpenStack Havana, networking: nova-network, Hypervisor: KVM, Libvirt
version: 1.1.1, QEMU version: 1.5.0, Host disk write cache: enabled,
Guest disk cache: none and host OS scheduler: CFQ.

Setting b): Controller & Compute node OS - Ubuntu 14.04, cloud software:
OpenStack Icehouse, networking: Neutron, Hypervisor: KVM, Libvirt
version: 1.2.2, QEMU version: 2.0.0, Host disk write cache: enabled,
Guest disk cache: none and host OS scheduler: CFQ.

May I know has anybody performed such tests and if yes, can you please
share details on the IO performance of VMs and the application?

I don't know whether is the right question to ask in this forum. Can
somebody share information at a high level about the improvements made
in Libvirt (from version 1.1.1 to 1.2.2) for handling IO requests?

Since you changed so many variables between setting a) and b), there's no 
possible way to say which one of those changes resulted in the degraded 
performance of MySQL.

You also have not given the different versions of MySQL you were running, nor 
provided the diffs of the my.cnf settings you used...

I'd recommend trying to reduce the delta of your environment changes and then 
re-running sysbench.

Best,
-jay

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