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Introduces a top-level dtrace/ directory for user-contributed trace scripts that consume the USDT probes exported by libdns, libns, and libisc. Ships with delegdb-trace.stp, which streams every insertion, eviction, and rndc flush-delegation removal in the delegation cache, and a README pointing at the provider files and explaining how to list and run the probes on Linux (SystemTap) and on FreeBSD/macOS (DTrace).
43 lines
1.3 KiB
Markdown
43 lines
1.3 KiB
Markdown
# dtrace/
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Example trace scripts for BIND 9's static user-space (USDT) probes.
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## What's instrumented
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BIND 9 ships USDT probes declared in three providers:
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- `lib/dns/probes-dns.d` — provider `libdns` (`xfrin_*`, `delegdb_*`)
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- `lib/ns/probes-ns.d` — provider `libns` (`rrl_*`)
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- `lib/isc/probes-isc.d` — provider `libisc` (`rwlock_*`, `job_*`)
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The probes compile to zero-cost nops when no consumer is attached, and
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are only wired up when the build finds `dtrace` and `sys/sdt.h` (meson
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option `-Dtracing=auto|enabled`, default `auto`). With
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`-Dtracing=disabled` the probe macros are stripped entirely.
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## Listing available probes
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On Linux (SystemTap / USDT):
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stap -l 'process("/path/to/named").mark("*")' | sort
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On FreeBSD or macOS (DTrace):
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dtrace -l -n 'libdns*:::*'
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## Scripts
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| Script | Purpose |
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|---|---|
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| [`delegdb-trace.stp`](delegdb-trace.stp) | Streams every insertion, eviction, and `rndc flush-delegation` removal in the delegation cache. |
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## Running a script
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The scripts take the `named` binary path as their first positional
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argument, so they work with either an installed or a freshly-built
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named:
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sudo stap dtrace/delegdb-trace.stp /usr/sbin/named -x $(pidof named)
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sudo stap dtrace/delegdb-trace.stp build/named -c "build/named -g -f"
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The `-c` form runs `named` under stap's supervision and exits with it.
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