Pressure Stall Information (PSI)

PSI provides for the first time a canonical way to see resource pressure increases as they develop, with new pressure metrics for three major resources—memory, CPU, and IO. These pressure metrics, in conjunction with cgroup2 and other kernel and userspace tools described below, allow you to detect resource shortages while they’re developing, and respond intelligently—by pausing or killing non-essentials, reallocating memory in the system, load shedding, or other actions. PSI stats are like barometers that provide fair warning of impending resource shortages, enabling you to take more proactive, granular, and nuanced steps when resources start becoming scarce.