set interfaces ethernet eth1 address '192.0.2.1/30'
set system option kernel memory default-hugepage-size '2M'
set system option kernel memory hugepage-size 2M hugepage-count '2048'
set system sflow interface 'eth1'
set system sflow interface 'eth2'
set system sflow server 127.0.0.1
set system sflow vpp
set vpp settings interface eth1 driver 'dpdk'
set vpp settings interface eth2 driver 'dpdk'
set vpp settings unix poll-sleep-usec '222'
set vpp sflow interface 'eth1'
commit

set vpp sflow interface eth2
commit

vyos@r14# commit
[ vpp sflow ]
Traceback (most recent call last):
  File "/usr/libexec/vyos/services/vyos-configd", line 156, in run_script
    script.apply(c)
  File "/usr/libexec/vyos/conf_mode/vpp_sflow.py", line 127, in apply
    vpp.cli_cmd(f'sflow enable-disable {interface}')
  File "/usr/lib/python3/dist-packages/vyos/vpp/control_vpp.py", line 81, in check_retval_wrapper
    raise VPPValueError(f'VPP API call failed: {return_value.retval}')
vpp_papi.vpp_papi.VPPValueError: VPP API call failed: -1

[[vpp sflow]] failed
Commit failed

[edit]
vyos@r14#