getaddrinfo/gethostbyname call latency sampler

[l2dy]

Reference: https://github.com/iovisor/bcc/blob/72dbe044395ccffd5249ed1f6c84a5fa4bd21be3/libbpf-tools/gethostlatency.bpf.c

[brayniac]

@l2dy - for this one, since this sampler is based around uprobes and not kprobes, I'm curious what you envisioned for this sampler. We'd need to attach the uprobes to each process on the system or have some mechanism for specifying and attaching to some group of processes.

Let me know if you had thoughts on this. Otherwise, I'm leaning towards closing this out.

[l2dy]

What I envisioned was that the uprobe is attached to the system's libc library, thereby probing all processes using it.

This method has its flaws like not working for statically linked binaries, so it's fine to close this if you consider it inappropriate.