8 Chapter 1. What is TUX?
1.1. New TUX 2.1 Features
The TUX 2.1 release is an incremental upgrade to TUX 1.0 and keeps source-code level com-
patibility with user-space modules.
The incremental enhancements include
• True zero-copy disk reads — Whereas TUX 1.0 copied files into a temporary buffer, TUX
2.1 is integrated with the page cache and thus uses zero-copy block IO.
• Generic zero-copy network writes— TUX 2.1uses the genericzero-copy TCP framework.
• Zero-copy parsing — Where possible, TUX parses input packets directly. Even in RAM-
limited situations, TUX now does full, back-to-back zero-copy I/O.
Other changes include
• Enhanceduser-space utilities and module support.
• Mass virtual hosting support — The host-based virtual server patch has been added to
TUX. Thereis nolimit onthe numberof virtualhosts supported,only RAMand diskspace.
• CGIs can be bound to particular CPUs or can be left unbound.
• A number of bugs were fixed which caused performance problems — TUX 2.1 is now
significantly faster than TUX 1.0!
1.2. Summary of System Requirements
• TUXCustomized 2.4.x-based version of the kernel or higher
• x86, Alpha, IA64 or PowerPC/64 platform (should work on PowerPC/32, untested on
Sparc)
• Alternate web server such as Apache running on the same server to process unknown
requests
1.2.1. Current Limitations
• TUX can only call the other Web server such as Apache on the same server. In future
revisions, it will allow the rollover of unsupported content to an alternate server.
