[PVE-User] linux idle cpu overhead in kvm - old issue, but still there in 2020...
devzero at web.de
Tue Jul 14 19:16:40 CEST 2020
what guest OS do you use and which showed the problem ?
as i think that q35 will not be default in kvm or proxmox anytime soon,
shouldn't we perhaps file a bug report for every distro affected ?
is there someone who likes to work with this (help testing,
writing/tracking bug reports...) ?
could perhaps save some tons of CO2 ....
Am 14.07.20 um 18:05 schrieb Atila Vasconcelos:
> Wow, I just tried this at my servers (very old Dell PowerEdge 2950);
> The results are impressive!
> On 2020-07-13 3:15 a.m., Roland wrote:
>> i have found that there is an old bug still around in linux, which is
>> causing quite an amount of unnecessary cpu consumption in kvm/proxmox,
>> and thus, wasting precious power.
>> i run some proxmox installations on older systems and on those, it's
>> quite significant difference.
>> on the slowest system, a single debian 10 VM , kvm process is at 20% cpu
>> (VM is 100% idle) when this issue is present.
>> if i change VMs machine type from i440fx(default) to q35 the problem
>> goes away.
>> the same applies when running "powertop --auto-tune" inside the guest
>> (with i440fx type - enable autosuspend for usb-controller + tablet
>> on some L5630 machine, in proxmox summary i see "CPU usage" drop from
>> 10% to <1%.
>> i guess this information could make a difference for people who run a
>> large amount of virtual machines or use older systems/cpu's.
>> on most recent cpu's, i think the difference is not that big.
>> anyway, i really wonder how linux bugs have such great survival
>> more references:
>> pve-user mailing list
>> pve-user at lists.proxmox.com
> pve-user mailing list
> pve-user at lists.proxmox.com
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