[CentOS-virt] Very high cpu waiting on xen domU
frederic.soulier at univ-tlse1.fr
Fri Oct 31 10:49:31 UTC 2008
I have some xen domU on Centos 5.2 server.
For some weeks i had a problem with "xen domU" performances.
Indeed my xen domU spend a lot of time in cpu waiting.
Reading some informations on the net it seems to come ith I/O heavy load.
Using collectd in my domU to monitor the "traffic" on virtual disk and
virtuel network i don't see heavy I/O rates.
Thinking my dom0 was overloaded by my domUs i have stopped all my domUs
except one but the problem persist.
I don't know how to get more informations in order to solve my problem.
For information our config is :
- Hitachi SAN infrastructure
- DELL 1950 servers with 2 qlogic hba adapters (we used qla2xx drivers
and linux dm-multipath for multipathing )
- We have 1 LUN on the SAN for each domU
- The dom0 manage theses LUNs using LVM
- A domU xen disk configuration looks like this : disk = [
- In the domU we doesn't use LVM.
- At the network level we share a gigabit interface with all the domU
using linux bridges. Each bridge refer to a different vlan.
Anyone encoutered I/O performances problems with latests centos 5.2 xen
releases ? (In fact i don't really understand if it's a xen problem or a
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