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Hi Dan,

Thanks for the pointer. I will try it out.

Regards,
Krishnaprasad

-----Original Message-----
From: Dan Yocum [mailto:dyocum at redhat.com] 
Sent: Dienstag, 30. Juni 2015 23:03
To: openstack at lists.openstack.org; Narayanan, Krishnaprasad
Subject: Re: [Openstack] MySQL IO performance

Krishnaprasad,

If you're using spinning disks, the host OS scheduler should be deadline, not CFQ.  If you're using SSD, it should be noop, just like the guest system.

I had similar performance problems, client timeouts, etc. between havana
-> icehouse and tweaking the scheduler resolved the issues.

Dan



On 06/29/2015 06:19 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?
> 
>  
> 
> Regards,
> 
> Krishnaprasad
> 
> 
> 
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--
Dan Yocum
Principal Systems Engineer
OpenShift on OpenStack by Red Hat
dyocum at redhat.com