Fine software projects, news and thoughts from the Linux world.

Soft scrollback for the Linux VGA console

If you're a heavy user of the Linux VGA console, you'll like this feature. Recent 2.6 kernels have added support for soft scrollback. This feature enables you to have much bigger scrollback buffer than the standard console has, at the price of slightly slower console output.

The scrollback buffer of the standard VGA console is located in VGA RAM. This RAM is fixed in size and is very small. To make the scrollback buffer larger, it must be placed instead in System RAM. We call this soft scrollback.

The feature and the size of the buffer are enabled/configured through kernel config options, during kernel compilation. Beside consuming kernel memory, enabling this feature will slow down the console by approximately 20%.

Ottawa Linux Symposium Proceedings

The Linux Symposium is a core technology conference, targeting software developers working on the Linux kernel, OS infrastructure, security, networking, and related research projects. With attendees coming from over 30 different countries, the Symposium is the single most comprehensive collection of Linux experts in the world.

Here you can find the proceedings from the last six years, 335 Linux white papers in total!

Authors retain copyright to all submitted papers, but have granted unlimited redistribution rights to all as a condition of submission.

The Digg Effect Analyzed

What is Digg?

Digg is a user driven social content website. Everything on digg is submitted by the digg user community, and after that other digg users read submissions and digg what they like best. When a story receives enough diggs, it is promoted to the front page for the millions of digg visitors to see.

The obvious effect on a website after a front page digg article is the huge increase in visitors and traffic. All those digg readers can saturate the site completely, causing the site to buckle under the strain. The Digg Effect is the term given to this phenomenon.

Running Linux on the ASRock 775Dual-VSTA motherboard

ASRock 775Dual-VSTAASRock 775Dual-VSTABeing a happy owner of the ASRock 775Dual-VSTA motherboard for a week, I decided to share my opinions about it and also give an advice or two to other people thinking about running Linux on it.

In short, this board is an exceptional piece of engineering and Linux runs GREAT on it. I'm not going to list all the specifications of the motherboard, because they're readily available on its official page, but let me go through the interesting features:

  • the board can use both DDR & DDRII memory (but not at the same time!)
  • you can equip it with AGP or PCIe graphics card, your choice
  • there's plenty of connectors for both older ATA or newer SATA drives
  • you can run any LGA 775 processor you can get hands on, including latest Intel Core 2 Duo (Conroe core)
  • the board is very affordable (or should I say dirt cheap)

Your favorite file system?

51% (4154 votes)
31% (2490 votes)
9% (747 votes)
2% (178 votes)
3% (222 votes)
3% (277 votes)
Total votes: 8068

How to sort IP addresses using the GNU sort utility

Need to sort list of IP addresses in shell? Here’s the invocation that works:

sort -n -t . -k 1,1 -k 2,2 -k 3,3 -k 4,4

Thanks for this tip goes to Paul Heinlein.

How to grep for IP addresses using the GNU egrep utility

CFQ to become the default I/O scheduler in 2.6.18

Judging by this commit, CFQ (Complete Fair Queuing) I/O scheduler will become the default one in the upcoming 2.6.18 kernel. For a long time, anticipatory scheduler has been the default, although even back in late 2004 there was some thinking about replacing it with CFQ. And it seems the time has finally come. CFQ scheduler has been gaining adoption since then, to the point that it's the default I/O scheduler for RHEL 4, Suse, and other distros.

One of the coolest things about CFQ is that it features I/O priorities (since 2.6.13). That means you can set the I/O priority of a process so you can avoid that a process that does too much I/O (daily updatedb) starves the rest of the system, or give extra priority to a process that shouldn't be starved by other processes, by using the ionice tool included in schedutils (since version 1.5.0).

ZFS filesystem for Linux?

ZFS is an advanced modern filesystem from Sun Microsystems, originally designed for Solaris/OpenSolaris.

ZFS has many features which can benefit all kinds of users - from the simple end-user to the biggest enterprise systems:

  • Provable integrity - it checksums all data (and metadata), which makes it possible to detect hardware errors (hard disk corruption, flaky IDE cables, etc...)
  • Atomic updates - means that the on-disk state is consistent at all times, there's no need to perform a lengthy filesystem check after forced reboots or power failures
  • Instantaneous snapshots and clones - it makes it possible to have hourly, daily and weekly backups efficiently, as well as experiment with new system configurations without any risks
  • Built-in (optional) compression
  • Highly scalable
  • Pooled storage model - creating filesystems is as easy as creating a new directory. You can efficiently have thousands of filesystems, each with it's own quotas and reservations, and different properties (compression algorithm, checksum algorithm, etc...)
  • Built-in stripes (RAID-0), mirrors (RAID-1) and RAID-Z (it's like software RAID-5, but more efficient due to ZFS's copy-on-write transactional model).
  • Many others (variable sector sizes, adaptive endianness, ...)

Advanced Linux Programming

The book written by Mark Mitchell, Jeffrey Oldham and Alex Samuel (CodeSourcery LLC), originally published by New Riders Publishing.

If you're a developer already experienced with programming for the GNU/Linux system, are experienced with another UNIX-like system and are interested in developing GNU/Linux software, or want to make the transition from a non-UNIX environment and are already familiar with the general principles of writing good software, this book is for you.

Advanced Linux Programming is published under the Open Publication License, Version 1, no options exercised.

Linux Device Drivers, 3rd Edition

This is the Third Edition of Linux Device Drivers, by Jonathan Corbet, Alessandro Rubini, and Greg Kroah-Hartman. For the moment, only the finished PDF files are available.

This book is available under the terms of the Creative Commons Attribution-ShareAlike 2.0 license. That means that you are free to download and redistribute it. The development of the book was made possible, however, by those who purchased a copy from O'Reilly or elsewhere.

LDD3 is current as of the 2.6.10 kernel. See the LWN 2.6 API changes page for information on subsequent changes.

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