While testing the AKS guide, I discovered that cilium monitor does not work with Cilium 1.8@f3b474ad3. As soon as I start cilium monitor (or enable Hubble), the agent crashes with failed to create perf ring for CPU 2: can't create perf event: can't create perf event: no such device. The crash itself will be addressed in #12068, but cilium monitor remains nonfunctional:

cilium monitor does not display any trace or drop events

$ cilium monitor
Listening for events on 128 CPUs with 64x4096 of shared memory
Press Ctrl-C to quit
>> Endpoint created: {"id":606,"pod-name":"pod-to-a-external-1111-7c5c99c6d9-ng8w7","namespace":"default"}
[ no trace/drop events ]

Cilium 1.7.5 works fine on the exact same cluster.
Note: The machine does not have 128 cpus, it has 2.

aksEngineVersion: v0.47.0-aks-gomod-55-aks
kubernetes: 1.15.11
zone: westeurope
os image: Ubuntu 16.04.6 LTS
kernel: Linux aks-ssh 4.15.0-1083-azure #93~16.04.1-Ubuntu SMP Thu May 7 18:39:44 UTC 2020 x86_64 GNU/Linux