Introduce ring buffers #163
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By default, the env var TMDIR is queried, which might not be shared in the test VMs.
Ring buffers offer several advantages compared to perf buffers, and they are the more modern solution for BPF -> userspace communication. They were introduced in Linux 5.8 so to ensure compatibility with older kernels this commit chooses ring buffers if they are available. This can be overriden with `--force-perf-buffer`. Two of the reasons why ring buffers are quite exciting are potentially less overhead when polling, thanks to the adaptative mechanism to try to balance overhead while minimising lost samples and sharing the memory for all the CPUs rather than having to have static per-CPU memory regions which can be less fair. Future work =========== The size of the ring buffers hasn't been tuned properly yet. Test Plan ========= Lots of manual tests + CI
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Introduce ring buffers
Ring buffers offer several advantages compared to perf buffers, and they
are the more modern solution for BPF -> userspace communication. They
were introduced in Linux 5.8 so to ensure compatibility with older
kernels this commit chooses ring buffers if they are available. This can
be overriden with
--force-perf-buffer.Two of the reasons why ring buffers are quite exciting are potentially
less overhead when polling, thanks to the adaptative mechanism to try to
balance overhead while minimising lost samples and sharing the memory
for all the CPUs rather than having to have static per-CPU memory
regions which can be less fair.
Future work
The size of the ring buffers hasn't been tuned properly yet.
Test Plan
Lots of manual tests + CI
vmtest: Specify architecture and use /tmp
By default, the env var TMDIR is queried, which might not be shared in
the test VMs.