pub fn instructions(
cmd: &[String],
dir: Option<&Path>,
settings: &Settings,
) -> Result<Option<Counted>>Expand description
Instruction count via valgrind --tool=cachegrind, repeated.
Reports the minimum, for the same reason wall clock does: the extra work a subject sometimes performs is one-sided. A run that consults the network or populates a cache can only retire more instructions than the quiet path, never fewer, so the floor is the stable estimator.
Returns Ok(None) when valgrind is unavailable rather than failing: this is
the expected state on macOS (no usable Apple Silicon support) and Windows.
Those platforms record timing only, and the CI gate lives on the Linux job.
Locally, a container gets you counters on any host.