This chapter briefly introduces tools that can be used to monitor and analyze system and application performance, and points out the situations in which each tool is most useful. The data collected by each tool can reveal bottlenecks or other system problems that contribute to less-than-optimal performance.
3.1. The proc File System
proc "file system" is a directory that contains a hierarchy of files that represent the current state of the Linux kernel. It allows applications and users to see the kernel's view of the system.
proc directory also contains information about the hardware of the system, and any currently running processes. Most of these files are read-only, but some files (primarily those in
/proc/sys) can be manipulated by users and applications to communicate configuration changes to the kernel.