Linux Tips #8



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*1. INTRODUCING TRINUX                 
        
Trinux is a small and portable version of Linux that has been
 stripped of nonessential components. In addition, it is
 enhanced with GPL security tools. The authors of Trinux are
 able to create a custom Linux distribution that occupies less
 than 5MB. You can find more info on Trinux at 

http://www.trinux.org


*2. PERFORMANCE TUNING: RESIDENT SET SIZE                 
        
One of the parameters of a process is called "resident set size,"
 which is the maximum amount of RAM that the process can use at
 any given time. Exceeding this limit causes paging, which
 degrades performance. System administrators and users can change
 the resident set size of a process to ensure optimal performance.


*3. PERFORMANCE TUNING: WHAT ARE MAJOR FAULTS?                 
        
A major fault is a memory access that forces the kernel to access
 the disk before the process can continue. Major faults occur,
 for example, when the process attempts to read parts of an
 executable file that have been swapped. Frequent major faults
 usually indicate that the system has insufficient memory or that
 the process has insufficient resident set size. Minor faults and
 major faults are similar except that major faults force a disk
 access, whereas minor faults do not result in a disk access. The
 runtime overhead of major faults is significant.


*4. WHAT'S IN A GLYPH?                 
        
Displaying a character on a terminal involves several steps of
 translation. First, the character code is received as input from
 the keyboard or a file. The second phase maps the character code
 to the current font to determine what shape, or glyph, should be
 displayed on the screen. For example, the decimal code 98 is
 translated into the glyph "b" when an English font is used.
 However, when an Arabic or mathematical font is used, the same
 code is translated to different glyphs.


*5. THE K DESKTOP ENVIRONMENT                 
        
The K Desktop Environment (KDE for short) suite offers a true
 graphical desktop that has advanced features, including
 drag-drop with integrated HTML display. KDE can be used instead
 of legacy graphical interfaces such as mwm, olwm, fvwm, and
 afterstep, which are based on Unix's X Window System. You can
 download the KDE suite at 

http://www.kde.org


*6. USING PIPES                 
        
Pipes provide the simplest form of interprocess communication
 (IPC). You can think of a pipe as a file that is shared by two
 processes. In general, one process writes information to a pipe
 and another reads from it. Pipes are also called "FIFOs" because
 their data is organized in a first-in first-out layout.


*7. UNNAMED AND NAMED PIPES                 
        
There are two types of pipes: unnamed pipes and named ones. An
 unnamed pipe is created whenever it is needed, and it is deleted
 when both the writer and the reader have closed it. Unnamed
 pipes do not exist in the file system (hence the name). In
 contrast, a named pipe has a file name. The file name of a named
 pipe can be used by two processes that do not share file
 descriptors to communicate through it.


*8. LINUX CERTIFICATION PROGRAMS                 
        
A new exams-based certification program has been initiated by Red
 Hat, Inc. It is targeted at beginner to network professional
 levels. Registrants will be required to demonstrate performance
 capabilities in various areas, including diagnostic testing and
 troubleshooting, installing and configuring Linux, performing
 essential administration, and setting up common IP-based network
 services. It is estimated that other vendors will follow suit.
 You can find more info on this certification program at 

http://www.redhat.com/products/training.html


*9. THE NEW INTERNET ADDRESSING SYSTEM: IP6V                 
        
Beginning July 15, the Internet began moving from its old
 addressing system, Internet Protocol version 4 (IP4v), to a
 radically new one, IP6v. The new IP6v addressing system is meant
 to solve the address space problem of IP4v, which supports only
 two billion distinct IP addresses. The Internet Engineering Task
 Force (IETF) started working on IP6v four years ago out of
 concerns that the Internet would eventually run out of unique
 addresses. It is estimated that Linux-based networking
 applications, Web servers, and browsers will gradually shift to
 the new protocol within the next 10 years.


*10. MEMORY PAGES AND PAGE ALIGNMENT                 
        
System memory is divided into units that are called "pages." A
 page consists of 4,096 bytes (4K) on Intel and SPARC
 architectures and 8,192 bytes (8K) on Alpha systems. A memory
 address is said to be "page-aligned" if it's the address of a
 page beginning. Thus, on 4K page size architecture, 4,096,
 12,288, and 413,696 are instances of page-aligned
 memory addresses.
