Hi list, I need some expert opinion on some problem I am facing with OpenStack+Ceph environment.
I running a 3+ node cluster with OpenStack Juno. It is using ceph RBDs as cinder volumes. Functionally setup is working fine. However my expectation are related to block performance of RBDs inside a VM. I am observing a throttling effect in 100%- 4K RR iops after a point. Lots of CPU cycles got wasted in iowait. I suspect a single iothread per VM is causing this.I came to know about few tuning parameter that libvirt provides. It looks pretty straight forward to set these parameter in domain xml . However I am not able to do so. I didn't find any way to pass these parameter form nova directly, and when I edit domain.xml directly using 'virsh edit' the changes vanish even after saving the xml properly.(I know it is not a clean way to this, but a hack) It could be validation problem:- ############ #virsh dumpxml instance-000000c5 > vm.xml #virt-xml-validate vm.xml Relax-NG validity error : Extra element cpu in interleave vm.xml:1: element domain: Relax-NG validity error : Element domain failed to validate content vm.xml fails to validate ################## Second approach I took was to setting QoS in volumes types. But there is no option to set iothreads per volume, there are parameters related to max_read/wrirte ops/bytes. Thirdly, editing Nova flavor and proving extra specs like hw:cpu_socket/thread/core, can change guest CPU topology however again no way to set iothread. It does accept hw_disk_iothreads(no type check in place, i believe ), but can not pass the same in domain.xml. Please suggest me a way to set the same. -- -Pushpesh _______________________________________________ OpenStack-operators mailing list [email protected] http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators
