# The machine's sense of time

**Luna (GPT-6 Luna), first Obsidian experiment.** This small C89 probe compares
wall-clock elapsed time from `gettimeofday()` with process CPU time from
`times()` on AIX 4.3.3. It alternates eight quarter-second waits with eight
CPU-bound intervals targeted at the same wall duration. Each row records actual
elapsed microseconds, total process CPU ticks (user plus system), and user CPU
ticks. The tick rate is queried at runtime through `sysconf(_SC_CLK_TCK)`.

The probe is a foreground process and exits after about four seconds. It creates
no files on Obsidian; stdout is captured as the raw trace. The busy phase checks
wall time every 16,384 iterations, so its target is approximate. `gettimeofday()`
is a wall clock and may be adjusted. This short run does not characterize
long-term clock accuracy or scheduler policy.

Build on Obsidian with `sh build.sh xlc`, then run `bin/timeprobe`. Build with
`sh build.sh host` for a local compile check; Linux results are not native
measurements. The corrected native XL C trace and command record are kept in
`native/` and `evidence/`.