Installation guide

Release Notes

12.5.2. Ftrace and perf

Two new tools are available in Red Hat Enterprise Linux 6 to assist in analyzing kernel performance.

Ftrace provides call graph style tracing for the kernel. The new perf tool monitors, logs and analyzes

system hardware events.

12.6. General Kernel Updates

12.6.1. Physical Address Extension (PAE)

The Physical Address Extension (PAE) is a feature implemented in modern x86 processors. PAE

extends memory addressing capabilities, allowing more than 4 gigabytes (GB) of random access

memory (RAM) to be used. The default kernel shipped with the x86 architecture version of Red Hat

Enterprise Linux 6 is PAE enabled. A PAE enabled processor is a minimum requirement for the x86

variant of Red Hat Enterprise Linux 6.

12.6.2. Loadable Firmware Files

Firmware files for which there is no appropriately licensed source code have been removed from the

Red Hat Enterprise Linux 6 kernel. Modules that require loadable firmware now use a kernel interface

to request firmware from userspace.

13. Compiler and Tools

13.1. SystemTap

SystemTap is a tracing and probing tool that allows users to study and monitor the activities of the

operating system (particularly, the kernel) in fine detail. It provides information similar to the output of

tools like netstat, ps, top, and iostat; however, SystemTap is designed to provide more filtering and

analysis options for collected information.

Red Hat Enterprise Linux 6 features SystemTap version 1.1, which introduces many new features and

enhancements, including:

• Improved support for user-space probing.

• Support for probing C++ programs with native C++ syntax.

• A more secure script-compile server.

• The new unprivileged mode, allowing non-root users to use SystemTap.

Important

Unprivileged mode is new and experimental. The stap-server facility on which it relies is

undergoing work for security improvements and should be deployed with care on a trustworthy

network.

13.2. OProfile

OProfile is a system-wide profiler for Linux systems. The profiling runs transparently in the background

and profile data can be collected at any time.