Re: [libvirt] [resend v2 0/7] Support cache tune in libvirt
On Mon, Feb 06, 2017 at 10:23:35AM +0800, Eli Qiao wrote:
This series patches are for supportting CAT featues, which also
called cache tune in libvirt.
First to expose cache information which could be tuned in capabilites XML.
Then add new domain xml element support to add cacahe bank which will apply
on this libvirt domain.
This series patches add a util file `resctrl.c/h`, an interface to talk with
linux kernel's sys fs.
There are still some TODOs such as expose new public interface to get free
cache information.
Some discussion about this feature support can be found from:
https://www.redhat.com/archives/libvir-list/2017-January/msg00644.html
Two comments:
1) Please perform appropriate filesystem locking when accessing
resctrlfs, as described at:
http://www.spinics.net/lists/linux-tip-commits/msg36754.html
2)
<cachetune id='10' host_id='1' type='l3'
size='3072' unit='KiB'/>
[b4c270b5-e0f9-4106-a446-69032872ed7d]# cat tasks
8654
[b4c270b5-e0f9-4106-a446-69032872ed7d]# pstree -p | grep qemu
|-qemu-kvm(8654)-+-{qemu-kvm}(8688)
| |-{qemu-kvm}(8692)
| `-{qemu-kvm}(8693)
Should add individual vcpus to the "tasks" file, not the main QEMU
process.
The NFV usecase requires exclusive CAT allocation for the vcpu which
runs the sensitive workload.
Perhaps:
<cachetune id='10' host_id='1' type='l3'
size='3072' unit='KiB'/>
Adds all vcpus that are pinned to the socket which cachebank with
host_id=1.
<cachetune id='10' host_id='1' type='l3'
size='3072' unit='KiB' vcpus=2,3/>
Adds PID of vcpus 2 and 3 to resctrl directory created for this
allocation.