On Wed, May 18, 2016 at 8:01 PM, Karli Sjöberg <karli.sjoberg@slu.se> wrote:
I tried a vanilla centos-7.1 as well and the same happens. I'm of the same opinion that this is more a guest related issue, it's just I'd like to find out why this only happens with QXL and not with CIRRUS.
Thanks.
Very interesting. Are your hosts all of the same architecture(family)?
/K
Actually we have a nice mixture of manufacturers. We run 7 hosts, paired 4-2-1 in relation to architecture. All of them have the same resources, though (CPUs + RAM). In this case, I can't test the VM on different hosts because we've separated one of them (one of the "4") on a standalone oVirt datacenter as we're making tests on it, but I remember this has already happened to me in the past (I didn't have the time to debug it at that time, though).
And it doesn't happen with a similar VM in the other datacenter, on the same hardware?
/K
Hello, I would like to come back to the original post to get some clarifications: you write " I've deployed a pretty basic VM (ubuntu 14.04 server, 4GB RAM, 4 CPUs, 15GB storage). " It seems to me not so basic a VM with 4 vcpus for a desktop.... what are your needs for it? In general a multi cpu VM could have a worse performance than a mono cpu one, depending on its actual workload, because from the host side there is a continuous scheduling of these 4 vcpus among the real cpus/cores/threads. I worked in the past with a 4 vcpu VM and 24Gb of ram (in vSphere) used as JDEdwards database server with hundreds of concurrent users ... Also with JBoss VMs configured with 4-6 vcpus .. But for a basic VM seems somehow overestimated... In my case on a nuc6i5 with 2 cores + ht and 32Gb of ram, configured as hypervisor with self hosted engine VM, I have a CentOS 6 VM configured with 3Gb of ram and 1 cpu and it runs quite smooth from inside a spice session configured with resolution of 1680x1050 and its cpu usage shows 98.5% idle. Also from the host point of view PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 16025 qemu 20 0 8988404 3.070g 10524 S 1.7 9.9 90:16.07 qemu-kvm <--- engine VM 24367 qemu 20 0 3852288 1.929g 12188 S 0.0 6.2 41:12.79 qemu-kvm <---- CentOS 6 VM If I add to the mix a CentOS 7.2 VM configured with 1 vcpu and 3Gb of ram and with a classic gnome desktop session and open it with 1680x1050 resolution too in spice, I can work without problems and with great fluidity. I see inside vm its cpu jumping from 1% to 6% because of gnome-shell. I see this at host side while in CentOS 7 VM the packagekitd daemon is downloading the updates and so it is comsuming cpu cycles, also due to virtual network activity PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 16025 qemu 20 0 9004796 3.077g 10524 S 2.0 9.9 90:27.34 qemu-kvm 24367 qemu 20 0 3852288 1.929g 12188 S 0.7 6.2 41:17.35 qemu-kvm 31277 qemu 20 0 4121224 2.116g 12056 S 16.3 6.8 2:13.80 qemu-kvm Otherwise very few cpu usage, after packagekitd completes its work; PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 16025 qemu 20 0 9004796 3.077g 10524 S 2.3 9.9 90:34.42 qemu-kvm 24367 qemu 20 0 3852288 1.929g 12188 S 0.7 6.2 41:20.42 qemu-kvm 31277 qemu 20 0 3834364 2.138g 12056 S 1.0 6.9 2:28.80 qemu-kvm HIH debugging, Gianluca