[libvirt-users] Resource control is not supported on this host

[Allence]

Libvirt release version V4.1.0
It add a element is cachetune
After we add this, We can use host-cpu-cache
But when i add it, my host get a error message:
"Resource control is not supported on this host"
Why?
Following is my environment:
kernel : 4.1.5,
libvirt : 4.1.0
qemu : 2.9
host : lfs-7.0


my add cachetune in xml:
<cachetune vcpus='0-3'>
<cache id='1' level='3' type='data' size='3' unit='MiB'/>
</cachetune>

[Michal Privoznik]

Post by Allence
Libvirt release version V4.1.0
It add a element is cachetune
After we add this, We can use host-cpu-cache
"Resource control is not supported on this host"
Why?

For Cache Allocation Technology you need support at CPU hardware level.
Currently, only less than dozen CPUs support it (all server level Xeons):

https://www.intel.com/content/www/us/en/communications/cache-monitoring-cache-allocation-technologies.html#xeoncmtcat

Michal

[Peter Krempa]

Post by Michal Privoznik

Post by Allence
Libvirt release version V4.1.0
It add a element is cachetune
After we add this, We can use host-cpu-cache
"Resource control is not supported on this host"
Why?

For Cache Allocation Technology you need support at CPU hardware level.
https://www.intel.com/content/www/us/en/communications/cache-monitoring-cache-allocation-technologies.html#xeoncmtcat

Also besides that, the feature depends on a kernel feature which was
broken upstream and deemed unusable and thus reverted. Until libvirt is
rewritten to use the new resource control interface, the feature will
not work with new kernels.

[Daniel P. Berrangé]

Post by Peter Krempa

Post by Michal Privoznik

Post by Allence
Libvirt release version V4.1.0
It add a element is cachetune
After we add this, We can use host-cpu-cache
"Resource control is not supported on this host"
Why?

For Cache Allocation Technology you need support at CPU hardware level.
https://www.intel.com/content/www/us/en/communications/cache-monitoring-cache-allocation-technologies.html#xeoncmtcat

Also besides that, the feature depends on a kernel feature which was
broken upstream and deemed unusable and thus reverted. Until libvirt is
rewritten to use the new resource control interface, the feature will
not work with new kernels.

IIUC, that only applies to the perf stuff for reporting cache usage of
a VM.

The reporter here was trying to use the cache allocation stuff for
partitioning which AFAIK hasn't changed it userspace API

Regards,
Daniel

[Allence]

Thanks, I got it. My CPU dose't support it

Post by Daniel P. Berrangé

Post by Peter Krempa

Post by Michal Privoznik

Post by Allence
Libvirt release version V4.1.0
It add a element is cachetune
After we add this, We can use host-cpu-cache
"Resource control is not supported on this host"
Why?

For Cache Allocation Technology you need support at CPU hardware level.
https://www.intel.com/content/www/us/en/communications/cache-monitoring-cache-allocation-technologies.html#xeoncmtcat

Also besides that, the feature depends on a kernel feature which was
broken upstream and deemed unusable and thus reverted. Until libvirt is
rewritten to use the new resource control interface, the feature will
not work with new kernels.

IIUC, that only applies to the perf stuff for reporting cache usage of
a VM.
The reporter here was trying to use the cache allocation stuff for
partitioning which AFAIK hasn't changed it userspace API
Regards,
Daniel
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