[$] Tracking pressure-stall information

All underutilized systems are essentially the same, but each overutilized
system tends to be overloaded in its own way. If one’s goal is to
maximize the use of the available computing resources, overutilization
tends not to be too far away, but when it happens, it can be hard to tell
where the problem is. Sometimes, even the fact that there is a problem at
all is not immediately apparent. The
pressure-stall information patch set
from Johannes Weiner may make life
easier for system
administrators by exposing more information about the real utilization
state of the system.

Source: LWN