Edition 1
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Phone: +1 919 754 3700
Phone: 888 733 4281
Fax: +1 919 754 3701
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To see the contents of the filemy_next_bestselling_novel
in your current working directory, enter thecat my_next_bestselling_novel
command at the shell prompt and press Enter to execute the command.
Press Enter to execute the command.Press Ctrl+Alt+F2 to switch to the first virtual terminal. Press Ctrl+Alt+F1 to return to your X-Windows session.
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. For example:
File-related classes includefilesystem
for file systems,file
for files, anddir
for directories. Each class has its own associated set of permissions.
Choose Mouse Preferences. In the Buttons tab, click the Left-handed mouse check box and click to switch the primary mouse button from the left to the right (making the mouse suitable for use in the left hand).→ → from the main menu bar to launchTo insert a special character into a gedit file, choose → → from the main menu bar. Next, choose → from the Character Map menu bar, type the name of the character in the Search field and click . The character you sought will be highlighted in the Character Table. Double-click this highlighted character to place it in the Text to copy field and then click the button. Now switch back to your document and choose → from the gedit menu bar.
Mono-spaced Bold Italic
or Proportional Bold Italic
To connect to a remote machine using ssh, typessh
at a shell prompt. If the remote machine isusername
@domain.name
example.com
and your username on that machine is john, typessh john@example.com
.Themount -o remount
command remounts the named file system. For example, to remount thefile-system
/home
file system, the command ismount -o remount /home
.To see the version of a currently installed package, use therpm -q
command. It will return a result as follows:package
.
package-version-release
Publican is a DocBook publishing system.
mono-spaced roman
and presented thus:
books Desktop documentation drafts mss photos stuff svn books_tests Desktop1 downloads images notes scripts svgs
mono-spaced roman
but add syntax highlighting as follows:
package org.jboss.book.jca.ex1; import javax.naming.InitialContext; public class ExClient { public static void main(String args[]) throws Exception { InitialContext iniCtx = new InitialContext(); Object ref = iniCtx.lookup("EchoBean"); EchoHome home = (EchoHome) ref; Echo echo = home.create(); System.out.println("Created Echo"); System.out.println("Echo.echo('Hello') = " + echo.echo("Hello")); } }
Real_Time_Installation_Guide - MRG Realtime Installation Guide
syscall
interface is compatible with standard Red Hat Enterprise Linux 5.6. These compatibility restrictions pertain only to kernel modules not supplied by Red Hat.
kernel-rt-trace
has less overhead than kernel-rt-debug
.
Vanilla
kernel does not include the MRG Realtime features. This is used to help distinguish whether bugs were introduced in the MRG Realtime features, or are inherent bugs in the baseline kernel. See Section 4.1, “Reporting Bugs” for more information.
Variant | Intended Usage | Notes |
---|---|---|
x86_64 (kernel-rt)
| Production - Standard 64-bit production kernel | |
x86_64 tracing (kernel-rt-tracing)
| Debugging - 64-bit trace kernel | Latency tracer enabled - Used to locate latency hotspots |
x86_64 debug (kernel-rt-debug)
| Debugging - 64-bit debugging kernel | Includes debugging options, with latency tracer disabled - Used to debug the MRG Realtime kernel |
x86_64 vanilla (kernel-rt-vanilla)
| Debugging - 64-bit base kernel | No MRG Realtime features, used for comparison |
yum
.
yum
command to install the MRG Realtime group:
# yum groupinstall "MRG Realtime"
MRG Realtime
group installs five packages:
rt-setup
sets up the basic environment required by MRG Realtime.
kernel-rt
is the standard MRG Realtime kernel package.
rtctl
is a startup script that sets the priorities of the various kernel threads.
rtcheck
is a program that tests the running system for MRG Realtime capabilities.
tuna
is a graphical tool used to manage your MRG Realtime application. For information on running Tuna, see the MRG Realtime Tuning Guide.
rpm -ql
command.
# rpm -ql rt-setup /etc/security/limits.d/realtime.conf # rpm -ql kernel-rt
RPM Package Name | Description | MRG Realtime Specific? | Required? |
---|---|---|---|
kernel-rt
| Low latency and pre-emption functionality | Yes | Yes |
rtctl
| System start-up script used to configure the default MRG Realtime scheduling priorities of kernel threads | Yes | Yes |
kernel-rt-firmware
| Firmware files loaded by some hardware drivers to enable them. | Yes | Yes |
kernel-rt-doc
| MRG Realtime documentation | Yes | Advised |
RPM Package Name | Description |
---|---|
kernel-rt-devel
| Headers and libraries for kernel development |
kernel-rt-trace
| MRG Realtime kernel with tracing functions compiled in |
kernel-rt-trace-devel
| Headers and libraries for development on trace kernel |
kernel-rt-debug
| MRG Realtime kernel with debugging functions compiled in (slow) |
kernel-rt-debug-devel
| Headers and libraries for development on debug kernel |
kernel-rt-vanilla
| Base kernel for comparisons |
kernel-rt-vanilla-devel
| Headers and libraries for development on vanilla kernel |
rt-tests
| Utilities for measuring system latencies and for proving that priority-inheritance mutexes function properly. |
rtcheck
| A program that tests the running system for MRG Realtime capabilities. |
perf
| Performance monitoring for the Linux kernel |
oprofile
, systemtap
and the crash utility for analyzing kernel crashdumps. The debugging packages consist of symbol tables and are quite large. For this reason, they are separately delivered from the other MRG Realtime packages.
RPM Package Name | Description |
---|---|
kernel-rt-debuginfo
|
Symbols for profiling and debugging use, such as oprofile or systemtap
|
kernel-rt-trace-debuginfo
| Symbols for profiling and tracing |
kernel-rt-debug-debuginfo
| Symbols for profiling and tracing |
kernel-rt-vanilla-debuginfo
| Symbols for profiling and tracing |
kernel-rt-debuginfo-common
| Common debuginfo files shared between the other debuginfo packages. |
grub.conf
to make it the default boot kernel. The grub.conf
file is located in /boot/grub/grub.conf
. View the file using your preferred text editor. It should look similar to the following:
default=1 timeout=5 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu title Red Hat Enterprise Linux (realtime) (2.6.33.2-rt13.13) root (hd0,0) kernel /vmlinuz-2.6.33.9-rt31.64 ro root=/dev/Root rhgb quiet initrd /initrd-2.6.33.9-rt31.64.img title Red Hat Enterprise Linux Server (2.6.18-194) root (hd0,0) kernel /vmlinuz-2.6.18-194 ro root=/dev/Root rhgb quiet initrd /initrd-2.6.18-194.img
(hd0,0)
. Change the value of default=
to 0
as follows and save your changes.
default=0 timeout=5 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu title Red Hat Enterprise Linux (realtime) (2.6.33.2-rt13.13) root (hd0,0) kernel /vmlinuz-2.6.33.9-rt31.64 ro root=/dev/Root rhgb quiet initrd /initrd-2.6.33.9-rt31.64.img title Red Hat Enterprise Linux Server (2.6.18-194) root (hd0,0) kernel /vmlinuz-2.6.18-194 ro root=/dev/Root rhgb quiet initrd /initrd-2.6.18-194.img
/etc/sysconfig/kernel
. This will ensure that the changes you made to the grub file will remain as the default when you perform a system upgrade. To edit this file, open it in any text editor. It should look similar to this:
# UPDATEDEFAULT specifies if new-kernel-pkg should make # new kernels the default UPDATEDEFAULT=yes # DEFAULTKERNEL specifies the default kernel package type DEFAULTKERNEL=kernel
DEFAULTKERNEL=
parameter to read kernel-rt
.
# UPDATEDEFAULT specifies if new-kernel-pkg should make # new kernels the default UPDATEDEFAULT=yes # DEFAULTKERNEL specifies the default kernel package type DEFAULTKERNEL=kernel-rt
uname
command as the root user at the shell prompt. Check the output for the RT
designation. If it appears, the MRG Realtime kernel is running.
[root@mrg-rt-server ~]# uname -a Linux mrg-rt-server.redhat.com 2.6.33.9-rt31.64.el6rt.x86_64 #1 SMP PREEMPT RT Tue May 10 00:49:01 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux
kexec/kdump
. Further information and instructions on how to configure your system to obtain kernel crash information can be found in the MRG Realtime Tuning Guide.
latency tracer
is a peak detector which is used to identify the longest running non-preemptable kernel codepaths. This is particularly useful for identifying whether non-deterministic performance results are attributable to the kernel or to user space components. In customer deployments, the tool is most useful to differentiate whether delays are in the kernel or the application.
ftrace
utility is used to analyze and debug latency and performance issues that occur outside of user-space. It has a variety of options that allow you to use the utility in a number of different ways. It can be used to trace context switches, measure the time it takes for a high-priority task to wake up, the length of time interrupts are disabled, or list all the kernel functions executed during a given period.
rmem.ko
rmem.ko
. This module is not loaded by default, and is provided only to meet the realtime Java conformance tests - specifically the Technology Compatibility Kit (TCK) test in the Real Time Specification for Java's (RTSJ) conformance suite. It is an RTSJ requirement of this conformance test that Java programs have direct access to physical memory. This /dev/rmem
capability allows user applications to map any arbitrary memory region.
unprotected_address_space=1
is specified as an option for the module in the grub.conf
file. If the rmem.ko
kernel module is explicitly loaded, the kernel will have a tainted
flag. In this case, Red Hat Global Support may require you to reproduce any problems without the presence of rmem.ko
.
rmem.ko
gives any application direct access to physical memory. Many normal security mechanisms are bypassed and the system becomes much more vulnerable to attacks by malicious users. For this reason, it is strongly suggested that this feature be used exclusively for RTSJ certification purposes only. DO NOT use the rmem.ko
module for production deployment.
grub.conf
file is the following, where the memsize
parameter is expressed in bytes.
alloc_rtsj_mem.size=memsize
vanilla
kernel variant. The vanilla
kernel is the unmodified upstream kernel build without the MRG Realtime additions.
vanilla
kernel.
Revision History | |||
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Revision 1-1 | Thu Sep 22 2011 | ||
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Revision 1-0 | Thu Jun 23 2011 | ||
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Revision 0.1-7 | Fri Jun 03 2011 | ||
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Revision 0.1-6 | Thu May 19 2011 | ||
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Revision 0.1-5 | Mon May 16 2011 | ||
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Revision 0.1-4 | Mon May 16 2011 | ||
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Revision 0.1-3 | Wed May 11 2011 | ||
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Revision 0.1-2 | Wed Apr 20 2011 | ||
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Revision 0.1-1 | Thu Mar 03 2011 | ||
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Revision 0.1-0 | Tue Feb 22 2011 | ||
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