Stop the Presses, LJ Index and more.
  • 1-4: The Rainier Web-Index Study

  • 5: viz: “A rough-coated, dough-faced, thoughtful ploughman strode through the streets of Scarborough; after falling into a slough, he coughed and hiccoughed.”

  • 6-7: USA Today

  • 8-11: Media Metrix, Inc.

  • 12-13 and 15: San Jose Mercury News

  • 14 and 18: National Public Radio

  • 16-17: Boston Globe

  • 19: San Jose Mercury News and Business 2.0.


It was six years ago this month that Phil Hughes wrote an article titled “Selecting Hardware for a Linux System”. Dust off the copy from your archives, or read it at the LJ web site (http://www.linuxjournal.com/lj-issues/issue7/2850.html).


While Linux has quickly emerged as a winning embedded operating system, the main reason has never been speed. In fact, some forms of embedded Linux, such as Lineo's popular Embedix, make Linux a “hard” RTOS (Real Time Operating System) by combining it with a second kernel built for real-time work. MontaVista Software, Inc., however, has been implementing Linux itself as an RTOS since the company was formed early last year, and has worked to improve the performance of the Linux kernel to the point where it qualifies—all by itself—as a “hard” real-time OS. At press time (September 9) for this issue, MontaVista has delivered what it claims is a hard real-time Linux kernel, based on the current 2.4 code version. The company claims that this new kernel is fully preemptable, and provides a 30-fold improvement in performance over the 2.4 base. Claimed worst case application responsiveness will be in the hundreds of microseconds. In an interview for Embedded Linux Journal (this month's supplement to LJ), James Ready, Montavista's president & CEO, said, “This isn't just a better embedded Linux. It's a better Linux.”

As for the new kernel itself, Ready explains that the real issue is not just responsiveness to interrupts, but preemptability. Also that making Linux preemptable involved leveraging the same engineering work that yields Symmetric Multi-Processing (SMP).

Hard Hat Linux is MontaVista's embedded Linux brand. The new version, which is expected to come out of peer review by January, will offer a real-time scheduler that features deterministic real-time application selection and dispatching, without altering standard Linux scheduling. There will also be an optional interrupt accelerator, based on technology from RTLinux, which is a product of FSMLabs of Albuquerque, New Mexico. This has a 5x claimed interrupt responsiveness improvement. The first prototype is for IA32 platforms and was available immediately at press time from ftp://ftp.mvista.com/ A technical paper explaining MontaVista's real-time developments is available at ftp.mvista.com/pub/Real-Time/2.4.0-test6/preempt.txt. Read the interviews with both Jim Ready and Lineo's Bryan Sparks in the current Embedded Linux Journal also see responses to MontaVista's announcement by TimeSys and Lineo on page 22.

—Doc Searls