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Re: "Microkernels rule!" and the Hurd
From: |
Arne Babenhauserheide |
Subject: |
Re: "Microkernels rule!" and the Hurd |
Date: |
Mon, 25 Aug 2008 07:53:05 +0200 |
User-agent: |
KMail/1.10.0 (Linux/2.6.25-gentoo-r6; KDE/4.1.0; x86_64; ; ) |
Hi Neal,
Many thanks for your information!
Could you write a counter-story/public reply for the Hurd-Wiki?
It needn't be long, but it should be available online.
Best wishes,
Arne
Am Mittwoch 13 August 2008 10:04:29 schrieb Neal H. Walfield:
> Gernot Heiser recently wrote an article, "Microkernels rule!" for
> Embedded.com about microkernels' bad reputation. I fully agree with
> the message of his article: operating systems based on microkernel
> technology don't necessarily have to be slow and can be made more
> robust than their monolithic counterparts. However, Gernot mentions
> the Hurd and incorrectly describes its position in history:
>
> Mach, an OS that was widely used as the basis of systems, ran into
> serious performance problems... There were spectacular failures,
> none more so than IBM's Workplace OS, which cost the company a cool
> two gigabucks...
>
> Needless to say, the experience with Mach and others created a bit
> of an image problem for microkernels (which didn't stop the GNU Hurd
> from repeating the mistakes of the past). However, back in 1993,
> Jochen Liedtke demonstrated that these performance problems weren't
> inherent in the microkernel concept.
>
> The Hurd did not repeat the errors of past. Work on the Hurd started
> in 1990. In GNU's Bulletin January, 1994 [1], you'll find an article
> detailing the Hurd's architecture. Workplace OS was conceived in
> 1991; it was deemed a failure around 1995. Jochen's article
> "Improving IPC by Kernel Design" was published in December 1993.
>
> Regarding, Workplace OS, its main goals were: machine independence,
> multiple personalities, and concurrent operation of personalities [3].
> The last two goals, as far as I am aware, were never a priority in the
> development of the Hurd. Further, Workplace OS had already adopted
> many second generation microkernel features, for instance, L3's
> synchronous IPC. In the major "Observations and Lessons" section of
> [3], this is not even mentioned; management, coordination, and focus
> are cited as the major problems.
>
> Finally, the architectural problems that we have identified with Mach
> [4] are not related to IPC. The most important are the lack of
> resource accounting, and the bad resource management (paging
> decisions). Regarding the implementation that we use, the major
> problems are unoptimized code (e.g., when evicting a bunch of pages,
> Mach always sends them one at a time to the manager), and the decades
> old code base which was designed for machines with tens of megabytes
> of RAM.
>
> Neal
>
>
> [0] http://www.embedded.com/columns/guest/208800243
>
> [1] http://www.gnu.org/bulletins/bull16.html#SEC13
>
> [2] Improving IPC by kernel design
> Jochen Liedtke
> SOSP December 1993
> http://portal.acm.org/citation.cfm?id=173668.168633
>
> [3] Workplace Microkernel and OS: A Case Study
> Brett D. Fleisch and Mark Allan A. Co
> Software--Practice and Experience
> May 1998
> http://portal.acm.org/citation.cfm?id=279869.279875
>
> [4] A Critique of the GNU Hurd Multi-server Operating System
> Neal H. Walfield and Marcus Brinkmann
> ACM SIGOPS Operating Systems Review
> July 2007
> http://portal.acm.org/citation.cfm?id=1278901.1278907
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