[vfio-users] Can no longer pin CPUs with libvirt

Rokas Kupstys rokups at zoho.com
Wed Mar 2 16:37:19 UTC 2016


As of recently without any change to libvirt config it started
misbehaving. If i use cpu pinning (<cputune> in xml) i cant start VM any
more. Error:
> Unable to write to
> '/sys/fs/cgroup/cpuset/machine.slice/machine-qemu\x2dwin.scope/vcpu0/cpuset.cpus':
> Permission denied
Permissions on relevant dir:
> % ls -lah /sys/fs/cgroup/cpuset/machine.slice
> total 0
> drwxr-xr-x 2 root root 0 Kov  2 18:32 .
> drwxr-xr-x 5 root root 0 Kov  2 18:30 ..
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cgroup.clone_children
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cgroup.procs
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cpuset.cpu_exclusive
> -rw-r--r-- 1 root root 0 Kov  2 16:29 cpuset.cpus
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cpuset.effective_cpus
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cpuset.effective_mems
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cpuset.mem_exclusive
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cpuset.mem_hardwall
> -rw-r--r-- 1 root root 0 Kov  2 16:29 cpuset.memory_migrate
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cpuset.memory_pressure
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cpuset.memory_spread_page
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cpuset.memory_spread_slab
> -rw-r--r-- 1 root root 0 Kov  2 16:29 cpuset.mems
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cpuset.sched_load_balance
> -rw-r--r-- 1 root root 0 Kov  2 18:30 cpuset.sched_relax_domain_level
> -rw-r--r-- 1 root root 0 Kov  2 18:30 notify_on_release
> -rw-r--r-- 1 root root 0 Kov  2 18:30 tasks
Any idea why this would be? libvirtd runs as root. Should work. I didnt
update libvirt when this appeared.

P.S. hope its not too offtopic, if it is - sorry




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