The new version of the core, or kernel, of Linux has several changes that make Linux better suited to powerful computers with numerous processors, a market dominated today by servers running versions of the Unix operating system on which Linux is based.
This version will be the first major change since 2.4.0 was released in January 2001. From its lowly roots as a student project Linus Torvalds began 12 years ago, the software has matured to become a major competitor to Microsoft and a key part of most computing companies' plans.
As expected, Linux leader and founder Torvalds announced the new kernel in a note to the kernel mailing list, expressing some satisfaction that most problems had been stamped out before the final update was delivered. "It's not the totally empty patch I was hoping for, but judging by the bugs I worked on personally, things are looking pretty good," Torvalds said.
Torvalds has been locking down the 2.6.0 test versions for months, and Andrew Morton, the programmer in charge of 2.6.0, has said he expected the software to be released in December. Torvalds formally passed the 2.6 baton to Morton in his announcement: "We'll work together, but Andrew is boss."
Torvalds said the remaining bugs were obscure and hard to find, giving as an example a problem that cropped up only with 16- or 32-processor servers with faulty hard drives.
At the top of Morton's list of changes coming with 2.6.0 is the ability to run on multiprocessor servers--the machines that run around the clock, handling tasks such as bank account management, stock trades, supermarket sales transactions and e-mail delivery. Whereas the 2.4 kernel works on servers with four or sometimes eight processors, the 2.6 kernels will stretch to 32-processor systems, Morton said.
Linux is showing fast growth in a slowly recovering server market. A total of $743 million in Linux servers was sold during the third quarter, a 50 percent increase over the same quarter in 2002, according to research firm IDC. "From the first quarter to the second quarter to the third quarter, we've seen an acceleration in the growth rate of Linux servers," IDC analyst Jean Bozman said.
In the first quarter, Linux servers accounted for 5.6 percent of server sales and 14.1 percent of units sold, IDC said. In the third quarter, Linux servers grew to 6.8 percent of revenue and 16.2 percent of shipments.
However, commercial use of the 2.6.0 kernel is still months off for most customers.
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According to Red Hat, SuSE's 2.6.0 schedule is too aggressive. "It's an important milestone, but it would be irresponsible to bring it to customers this summer and say, 'Here it is--what you've been waiting for.' There are going to be a lot of ripples with it," Stevens said.
The company hopes to put the 2.6.0 kernel through its paces in its hobbyist version of Linux, called Fedora Core 2, which Red Hat expects to release in April, Stevens said. Even more experimental people have already been able to download rough-hewn 2.6.0 test versions from both Red Hat and SuSE.
Red Hat, which IDC said garnered 69 percent of global Linux operating system sales revenue in 2002, doesn't feel an urgent need to upgrade to 2.6. Several of its features have been adapted to its 2.4-based products, a process called "backporting."
Several key Linux programmers are employed by Red Hat and, therefore, the company has an easier time directing when a backport should take place. Among 2.6 features that were backported and that are available in Red Hat Enterprise Linux 3, released in October, is new networking and "threading" software that controls how the operating system juggles several simultaneous tasks.
Storage improvements
However, Stevens said Red Hat is eager for changes in 2.6, regarding how Linux handles reading and writing information stored on hard drives. SuSE's Garloff is equally enthusiastic. "The way it handles input-output requests are much improved in 2.6," he said.
Specifically, the two say computers that use the 2.6 kernel won't be as susceptible to "thrashing," which forces consumers to wait as the computer labors under heavy hard-disk traffic loads. In some cases, a storm of read-and-write requests under 2.4 could overtax the computer to the point that it would crash, Stevens said.
Another storage improvement Stevens awaits with 2.6 is a better volume manager--software that lets a program read and write information on hard drives more flexibly. Volume managers let hard drives be pooled together, making it possible to switch hard drives, expand capacity and make other changes without disturbing the programs using that storage.
The 2.4 kernels were also weak when used at large companies with servers that must tap into numerous storage systems across a network, with limits of between 128 and 256 storage systems accessible, Stevens said. The 2.6 kernel removes this "device space" limitation, he said.
Linux will also be able to use much larger file systems. The 2-terabyte limit of 2.4 is removed in 2.6, Garloff said.
Some steps back
Not everything is better, though. Garloff said the part of 2.6 that communicates with memory is less efficient, imposing a practical limit of 24GB of memory to the 32GB that 2.4 could handle. However, he believes that programmers will address the problem.
The new kernel also monitors for new events more frequently--1,000 times per second instead of 100--a fact that slows down the system about 1 percent, Morton said in an October presentation about the kernel.
In addition, 2.6 requires somewhat more memory to run and shows worse performance when it has to use hard drives as extra memory under heavy loads, Morton said.
