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From: | Dennis Jacobfeuerborn |
Subject: | [Qemu-devel] qemu-kvm idle guest using 10% cpu and causes significant increase of read_hpet calls on host |
Date: | Sat, 30 Jul 2011 15:14:48 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:5.0) Gecko/20110719 Thunderbird/5.0 |
Hi,I've started running a Centos6 minimal install virtual machine on a Centost6 host and noticed that even when the guest is completely idle the qemu-kvm process on the host shows up with 10% cpu usage on in "top".
Using perf and oprofile I noticed that once the guest is running the amount of read_hpet calls increases by a factor of 10. So I went and booted the host with "hpet=disable" which resulted in the qemu-kvm process now showing up with 15% cpu usage instead of 10%. So this seems to have an impact but certainly not the intended one.
I'm not well versed in these matters so I'm looking for any pointers in terms of for example kernel options I could test on the guest/host to find out what the cause of this is.
I opened a bug here: http://bugs.centos.org/view.php?id=5028According to one developer this is also seen by users on RHEL6 and SL6 which is why I decided to ask for help here since it doesn't seem to be a distribution specific problem.
Regards, Dennis
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