Re: Documentation on eBPF map types?


Brendan Gregg
 

I did some in the bcc ref guide, but it's incomplete, and the bcc versions: https://github.com/iovisor/bcc/blob/master/docs/reference_guide.md

Brendan

On Fri, Jan 27, 2017 at 9:54 PM, Jesper Dangaard Brouer via iovisor-dev <iovisor-dev@...> wrote:
Hi IOvisor/eBPF people,

Do we have some documentation on eBPF maps?

Like that map types are available, and what they are useful for?

Notice, just list listing[1] the enum is not so useful:

 enum bpf_map_type {
        BPF_MAP_TYPE_UNSPEC,
        BPF_MAP_TYPE_HASH,
        BPF_MAP_TYPE_ARRAY,
        BPF_MAP_TYPE_PROG_ARRAY,
        BPF_MAP_TYPE_PERF_EVENT_ARRAY,
        BPF_MAP_TYPE_PERCPU_HASH,
        BPF_MAP_TYPE_PERCPU_ARRAY,
        BPF_MAP_TYPE_STACK_TRACE,
        BPF_MAP_TYPE_CGROUP_ARRAY,
        BPF_MAP_TYPE_LRU_HASH,
        BPF_MAP_TYPE_LRU_PERCPU_HASH,
 };

[1] http://lxr.free-electrons.com/source/tools/include/uapi/linux/bpf.h?v=4.9#L78

I also lack some documentation about how I interact with these maps...

--
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer
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