Function parse_psi_line 

pub fn parse_psi_line(buf: &[u8]) -> Option<PsiLine>

Parse one line of /proc/pressure/<resource>.

some avg10=0.00 avg60=0.00 avg300=0.00 total=0

Parsed by key rather than by position: the kernel has added keys to this file before, and a positional parser would silently shift every value when it does again.