RHEA-2012:0047 - Product Enhancement Advisory

Topic

Updated Red Hat Enterprise MRG Realtime packages that add several enhancements
are now available for Red Hat Enterprise MRG 2.1 for Red Hat Enterprise Linux 6.

Description

Red Hat Enterprise MRG (Messaging, Realtime, and Grid) is a next-generation IT
infrastructure for enterprise computing. MRG offers increased performance,
reliability, interoperability, and faster computing for enterprise customers.

MRG Realtime provides the highest levels of predictability for consistent
low-latency response times to meet the needs of time sensitive workloads. MRG
Realtime provides new levels of determinism by optimizing lengthy kernel
codepaths to ensure that they do not become bottlenecks. This allows for better
prioritization of applications, resulting in consistent, predictable response
times for high-priority applications.

This update adds the following enhancements:

• The rt-tests package includes a set of programs that test and measure various

components of real-time kernel behavior. This package measures timer, signal,
and hardware latency and tests the functioning of priority-inheritance mutexes.
With this update, utility routines for mounting debugfs and event and tracing
manipulation have been added. (BZ#743962)

• The rt-setup package configures settings required by the Red Hat Enterprise

Linux real-time environment, such as creating the real-time group, adding
real-time user privileges to PAM (Pluggable Authentication Models), enabling the
configuration of the kdump utility in real time, and disabling the irqbalance
daemon by default. This update adds the cgroup setup logic for CPU isolation and
grouping of threads on cores and sockets. (BZ#723311)

• The tuna package provides graphical and command-line interfaces for changing

scheduler and interrupt request (IRQ) settings. Changes can be made to CPUs, by
thread or at the IRQ level, taking into account the topology of multi-socket and
multi-core systems. Tuna gives the ability to isolate CPU cores and sockets for
use by a specific application or hardware device. This update upgrades tuna to
use the Red Hat Enterprise Linux 6 numpy package to replace the previously used
python-numeric extension. (BZ#725801)

• Previous versions of the tuna utility regularly polled /proc/[PID] directories

to gather information about processes and threads, which may have led to a
workload disturbance. To avoid this, the tuna utility has been adapted to use
the perf events infrastructure. (BZ#666958)

• The rtctl package contains a set of scripts, which are used to manipulate the

scheduling priorities of groups of system threads. With this update, rtctl has
been modified to allow 3.0.x Realtime kernels to run with default priorities for
the ksoftirqd daemon and the kthreads library, which is different from previous
2.6.x Realtime kernels. (BZ#748974)

• In the MRG Realtime 2.1 kernel, the new uname26 utility activates the 2.6

personality kernel patch to transform data returned by the uname(2) system call
to the format of "2.6.40.[minor_release_number]".

• Some applications use flawed versioning logic that cannot recognize new Linux

kernel versions in the format of "3.x.y". As a workaround to this bug in
external applications, the new uname26 utility has been added to MRG Realtime
2.1 kernel. This utility activates the 2.6 personality kernel patch to transform
data returned by the uname(2) system call to the format of
"2.6.40.[minor_release_number]", and then executes the actual application.
(BZ#750336)

Users of the real-time capabilities of Red Hat Enterprise MRG 2.1, which is
layered on Red Hat Enterprise Linux 6, are advised to upgrade to these updated
packages, which add these enhancements.

Solution

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259

Affected Products

• MRG Realtime 2 x86_64

Fixes

• BZ - 750336 - RFE: add wrapper executable package for 2.6 personality feature

CVEs

(none)

References

(none)