Latest Linux kernel draws positive reviews

The newest Linux kernel has a bundle of features that should make it more attractive to companies and better able to compete with the likes of Windows NT and Unix, say those who helped write and test the open source software.

The Linux 2.4 kernel was unveiled on the kernel.org Web site Jan. 4 and distributed to mirror sites for downloading almost immediately. It will likely be a few months before companies such as Caldera and Red Hat start integrating the kernel into their Linux operating system distributions.

Experts say the most important features of the new kernel are its support for multiprocessing and additional platforms, as well as the inclusion of a logical volume manager (LVM) that changes the way files and volumes are managed. The kernel will support up to 32 processors in Intel machines, but so far has only been tested in machines with four to eight processors. In addition to working on Intel 32-bit platforms, the kernel will also run on the Intel 64-bit Itanium platform when available, IBM S/390 mainframes, Windows CE hardware and the 64-bit MIPS processor. LVMs are common in enterprise-class Unix systems, such as HP-UX and Compaq's Tru64 Unix.

"We do numerical air quality simulation at the NCSC," says Carlie Coats, a senior mathematician at the North Carolina Supercomputing Center in Research Triangle Park, N.C. "Our air quality forecast work uses 24 processors worth of SGI Origin [supercomputers], but we could easily take advantage of an order of magnitude more processing power to generate better forecasts."

The kernel also provides faster I/O to peripheral devices, supports RAID, more Integrated Drive Electronics (IDE) drives and larger file sizes.

"The 2.4 kernel supports [burst transfers and larger IDE drives], and the SCSI layer deals much better with errors and also scales better than before," says Alan Cox, a kernel hacker in Wales. "Both of these [features] are obviously important in large data centers or when running databases."

Cox, a well-known developer in the Linux community, is responsible for maintaining the patches to the kernel and wrote much of its symmetric multiprocessing and networking code.

"The [2G-byte file size of the previous kernel] was a fine limit until 45G-byte disks became available," Cox says. "Video editing and large databases are both using very large files now, so Linux 2.4 supports about a terabyte or so per file."

Users are welcoming that extra oomph.

"I've used a few files over 2G-byte [in size], mostly restored archives and video files," says Bill Rugolowsky, a programmer for a New York securities firm. "As I start using Linux for more data modeling, the data sets will no doubt grow to that size."

The 2.4 kernel also makes it possible for 4.2 billion users to be connected to a Linux net.

"This is useful for large sites, in particular where [Lightweight Directory Access Protocol] is used to join networks with a single user database," Cox says.

In addition, the point-to-point protocol, which is part of the Linux kernel, has been rewritten to support DSL and broadband services, as well as ATM. A server running the Linux 2.4 kernel can also contain up to 20 drives and 16 Ethernet adapters, "allowing sites with a large number of subnets, as well as those trying out multilink setups, to increase bandwidth," says Brian Ward, a systems administrator at the University of Chicago. Multilinking allows the use of multiple devices or circuits simultaneously to speed communications.

The kernel also supports up to 64G bytes of RAM, important for "large servers, where network, memory and disk access all tend to converge," Ward says. "Even an improvement of a few milliseconds means a lot when there are 200 processes doing the same thing."

This story, "Latest Linux kernel draws positive reviews" was originally published by Network World.

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