Summary
I am unable to add an additional VPP worker core on an 8-core CPU system, even after applying CPU isolation parameters. The commit fails with the error: "Cannot set VPP "cpu corelist-workers": Not enough free CPUs in the system." This seems like a validation bug, as there should be enough isolated cores available.
Hardware
CPU: Intel(R) Xeon(R) E-2288G @ 3.70GHz, 8 physical cores (no Hyper-Threading, as per /proc/cpuinfo: cpu cores: 8, siblings: 8)
Memory: 16 GB
NIC: Mellanox MT27800 (ConnectX-5)
Full /proc/cpuinfo output attached:
DMI/hardware details: Supermicro X11SCL-F motherboard
set vpp settings cpu main-core '1' set vpp settings cpu corelist-workers '2' set vpp settings cpu corelist-workers '3' set vpp settings cpu corelist-workers '4' set vpp settings cpu corelist-workers '5' set vpp settings cpu corelist-workers '6' # Isolation: set system option kernel cpu isolate-cpus '1-7' set system option kernel cpu nohz-full '1-7' set system option kernel cpu rcu-no-cbs '1-7'
Steps to Reproduce
- Set up VPP with 5 workers (cores 2-6) and main-core 1 — commits successfully.
- Apply CPU isolation as above, commit, save, reboot.
- Try to add worker 7: set vpp settings cpu corelist-workers '7'
- Commit — fails with:
[ vpp ] Cannot set VPP "cpu corelist-workers": Not enough free CPUs in the system. [[vpp]] failed Commit failed
Alternative attempt: Move main-core to 0 and workers to 1-7 — same error.
cat /proc/cmdline BOOT_IMAGE=/boot/2025.08.28-0019-rolling/vmlinuz boot=live rootdelay=5 noautologin net.ifnames=0 biosdevname=0 vyos-union=/boot/2025.08.28-0019-rolling mitigations=off intel_idle.max_cstate=0 processor.max_cstate=1 isolcpus=1-7 nohz_full=1-7 rcu_nocbs=1-7 hugepagesz=1G hugepagesz=2M hugepages=3600 console=tty0 intel_iommu=on modules_load=vfio,vfio_iommu_type1,vfio_pci
cat /sys/devices/system/cpu/isolated