pub fn read_gpu_usage(proc_root: &Path, pid: Pid) -> Option<GpuUsage>Expand description
Read /proc/<pid>/fdinfo/* and sum every DRM descriptor’s counters.
§Cost
One readdir plus one open/read per file descriptor. On a desktop this is a
few thousand small reads per sample, which is why it is gated behind
ScanOptions::gpu — the same treatment smaps_rollup gets. A process with no
descriptors (kernel threads have no fd directory at all) costs one failed
readdir.
None means “no GPU work visible”: either the process holds no DRM fd, or the
files are unreadable because it belongs to another user.