Function memory_availability_probe_count 

pub fn memory_availability_probe_count() -> u64

Number of completed OS/cgroup availability probes in this process.

Every resample_memory_availability call opens and parses /proc/meminfo plus the four to five cgroup files behind detect_cgroup_memory, so this counter is a direct census of that syscall traffic. It exists so a planner can assert in a test that its budget decisions cost a bounded number of probes rather than one per unit of work (#2560).