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.