[Qemu-discuss] Performance Issues with qemu-kvm 0.12.1.2: Updating Questions

[Steve Amerige]

Hi,

I've just joined this group as I've been using qemu-kvm as it is made available to me via CentOS 6.4 x64:

    qemu-kvm-0.12.1.2-2.355.0.1.el6.centos.2.x86_64

The issue for me is that qemu-kvm consumes a lot of CPU even when the guests (Windows mostly, but also CentOS guests) are all idle.

top - 08:41:35 up 68 days, 23:15,  3 users,  load average: 4.78, 5.10, 4.97
Tasks: 555 total,   1 running, 554 sleeping,   0 stopped,   0 zombie
Cpu(s):  2.0%us,  2.1%sy,  0.0%ni, 83.3%id, 12.6%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:  132112512k total, 95524192k used, 36588320k free,     5564k buffers
Swap: 150994936k total,  6036376k used, 144958560k free,    27560k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
32507 root      20   0 19.7g  15g 1548 S 17.3 12.4 100:12.13 qemu-kvm
 4047 root      20   0 19.7g  15g 1012 S 14.6 12.7  13553:29 qemu-kvm
 4719 root      20   0 20.5g  15g 1016 S 12.6 12.7  10208:44 qemu-kvm
20430 root      20   0  703m  74m 6940 S 12.6  0.1 155:17.60 python

I've done some googling and see that there have been performance improvements on qemu-kvm that happened as of 0.12.4.  I find it odd that CentOS 6.4 is so far behind (0.12.1.2 compared to 1.3.1 or 1.4.1 that I see on the qemu.org download page).  Is the qemu-kvm that comes with CentOS 6.4 from some other development organization?

The question is: can I replace the qemu-kvm on the CentOS 6.4 x64 system to fix this performance problem?  Do I have to install more than just the qemu-kvm?  Is there an RPM that I can use to install this?  Or, do I need to compile from sources.

Any advice is appreciated.  If I've asked questions that have wrong assumptions, please correct me.  Also, please feel free to ask for clarification if you need any more info.

Many thanks,
Steve Amerige