New Linux kernel adds networking priorities

By Robin Schreier Hohman
Network World Fusion, 01/27/99

The first official Linux kernel released in about two years contains no big surprises, but offers a load of bug fixes and enhancements, as well as faster file access, and support for new devices and protocols.

For the enterprise, the most significant features include enhanced support for SMP (Symmetric MultiProcessing). In previous versions of Linux, only one processor can be handled by the kernel at a time. With 2.2., the kernel has been broken down into smaller pieces so that one area could be handling networking, while another could be accessing file systems. This makes each additional processor more effective than it was in earlier versions.

There is also support for the Internet protocols IPv6 (Internet Protocol version 6) and SPX (Sequenced Packet Exchange). IPv6 is a 128-bit enhanced version of TCP/IP; SPX runs on top of IPX (Internetwork Packet Exchange), NetWare's protocol for transporting information across the network. Support for the new protocols will likely increase Linux' already growing presence on Web and mail servers. The support for Ipv6 will evolve since it's not yet standardized.

On the hardware side the new release supports Gigabit Ethernet, Fibre Channel, and more Ethernet devices. A lot of the new device drivers have been added to 2.0.36, the current stable kernel of Linux, says Michael Johnson, software engineer at Red Hat, a company that sells Linux.

While TCP/IP has been supported in previous versions of Linux, the code has been upgraded to reflect "current best practices," according to Johnson. That means it conforms to research that's been done in TCP/IP since version 2.0's release two years ago. The new version also supports DecNet, DEC's proprietary Ethernet LAN.

Firewalling has also gotten a boost with the use of IP chains, which makes it easier for a systems administrator to set up a more complex security, Johnson says.

Support for RAID (Redundant Array of Inexpensive Disks) has also been greatly improved, according to Johnson. Linux 2.2 will allow you to hot swap in a new disk. With previous versions of Linux, you had to run a command to tell the operating system about a failed disk.

The new version has been ported to Motorola's 68000 line and PowerPC processors, which means it will run on all Macintosh computers. However, more work has to be done on drivers before some Macs will run Linux well.

Overall, the new version has better memory management. It's been reworked to deal with larger swap areas, making swaps more efficient. That means the OS spends less time looking for a place to temporarily store files when you're low on memory, making it store and retrieve files faster.

There's also been a significant change to the way Linux looks up the names of files, resulting in much faster file access in general, Johnson says. It now uses a cache designed specifically for looking up file names, especially lots of small files, such as e-mail and news.

There are extensive improvements to the Network File System, both at the server and client levels. Linux 2.2 now supports two different kinds of NCP (NetWare Core Protocol) long file names, NetWare's access to file and print services. The changes will make it significantly faster to access files.

IRDA (InfraRed Data Association) is supported in version 2.2, which means you can zap information between devices without cabling.

One thing that hasn't been addressed is a memory management error that makes it possible for someone to deliberately crash the system. A bug fix will be released shortly.

Only Linus Torvalds - the man who wrote the original kernel and tacked it onto the GNU project - can bless an official release. As one Linux developer put it, the kernel is ready, "when Linus says it's ready."

Last week's release of Linux 2.2.0 is considered to be a stable release; in other words, not buggy. There have been numerous incremental releases since version 2.0. In the Linux world, releases designated with an even number are considered to have most of the bugs worked out. Incremental, or developmental releases, have odd numbers, such as 2.1.

Both Caldera Systems, another Linux vendor, and Red Hat said they'll incorporate version 2.2.x after they've tested it and found it to be stable. Neither vendor could predict when that would be.