Posted by
michael
on from the oh-christmas-tree dept.
BigFire writes "Professor Tanenbaum responds to the slashdot effect and a small critique of Ken Brown's forthcoming book in his followup. A small gem is where he disclosed that Ken Brown can't multiply simple positive integers."
Article text
by
Anonymous Coward
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· Score: 5, Informative
Ken Brown's Motivation, Release 1.2
Background
On 20 May 2004, I posted a statement refuting the claim of Ken Brown, President of the Alexis de Tocqueville Institution, that Linus Torvalds didn't write Linux. My statement was mentioned on Slashdot, Groklaw, and many other Internet news sites. This attention resulted in over 150,000 requests to our server in less than a day, which is still standing despite yesterday being a national holiday with no one there to stand next to it saying "You can do it. You can do it." Kudos to Sun Microsystems and the folks who built Apache. My statement was mirrored all over the Internet, so the number of true hits to it is probably a substantial multiple of that. There were also quite a few comments at Slashdot, Groklaw, and other sites, many of them about me. I had never engaged in remote multishrink psychoanalysis on this scale before, so it was a fascinating experience.
The Brown Book
I got an advance copy of Ken Brown's book. I think it is still under embargo, so I won't comment on it. Although I am not an investigative reporter, even I know it is unethical to discuss publications still under embargo. Some of us take ethics more seriously than others. So I won't even reveal the title. Let's call it The Brown Book. There is some precedent for nicknaming books after colors: The International Standard for the CD-ROM (IS 10149) is usually called The Red Book.
Suffice it to say, there is a great deal to criticize in the book. I am sure that will happen when it is published. I may even help out.
Brown's Motivation
What prompted me to write this note today is an email I got yesterday. Actually, I got quite a few:-) , most of them thanking me for the historical material. One of yesterday's emails was from Linus, in response to an email from me apologizing for not letting him see my statement in advance. As a matter of courtesy, I did try but I was using his old transmeta.com address and didn't know his new one until I got a very kind email from Linus' father, a Finnish journalist.
In his email, Linus said that Brown never contacted him. No email, no phone call, no personal interview. Nothing. Considering the fact that Brown was writing an explosive book in which he accused Linus of not being the author of Linux, you would think a serious author would at least confront the subject with the accusation and give him a chance to respond. What kind of a reporter talks to people on the periphery of the subject but fails to talk to the main player?
Why did Brown fly all the way to Europe to interview me and (and according to an email I got from his seat-mate on the plane) one other person in Scandinavia, at considerable expense, and not at least call Linus? Even if he made a really bad choice of phone company, how much could that cost? Maybe a dollar? I call the U.S. all the time from Amsterdam. It is less than 5 cents a minute. How much could it cost to call California from D.C.?
From reading all the comments posted yesterday, I am now beginning to get the picture. Apparently a lot of people (still) think that I 'hate' Linus for stealing all my glory (see below for more on this). I didn't realize this view was so widespread. I now suspect that Brown believed this, too, and thought that I would be happy to dump all over Linus to get 'revenge.' By flying to Amsterdam he thought he could dig up dirt on Linus and get me to speak evil of him. He thought I would back up his crazy claim that Linus stole Linux from me. Brown was wrong on two counts. First, I bear no 'grudge' against Linus at all. He wrote Linux himself and deserves the credit. Second, I am really not a mean person. Even if I were still angry with him aft
Round Two
by
Anonymous Coward
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· Score: 5, Funny
"This attention resulted in over 150,000 requests to our server in less than a day, which is still standing despite yesterday being a national holiday with no one there to stand next to it saying "You can do it. You can do it." Kudos to Sun Microsystems and the folks who built Apache."
Just when he thought it was over, here we come for another round. . .
On Wall Street, we called this technology "BOHICA": Bend Over, Here It Comes Again.
--
--
make install -not war
Raises some interesting questions
by
Anonymous Coward
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· Score: 5, Funny
Some of which are easier to answer than others:
Why did Brown fly all the way to Europe to interview me and (and according to an email I got from his seat-mate on the plane) one other person in Scandinavia, at considerable expense, and not at least call Linus?
I think the answer is "because calling Linus wouldn't have allowed Brown to get the Alex de Torqeville Institute to pay for him to take a vacation to Holland".
The Netherlands Connection is the key
by
Vengeance
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· Score: 5, Funny
There is no other way to explain the conclusions we've seen reported for this book, except that Brown spent a good deal of time in Amsterdam coffeehouses, consuming high-grade grass.
-- It was a joke! When you give me that look it was a joke.
Changed opinion
by
Dasein
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· Score: 5, Insightful
You know, I think I had AST wrong. I'd seen the thread where he bashes Linus for not doing a microkernel design and thought that maybe it was sour grapes.
His exchanges on this subject have changed my opinion on that. He's been nothing but kind toward Linus, generous with his time, and well-spoken.
If anything good come out of this whole mess, maybe it's that AST really got to show us what he's really like instead of all of us just assuming that he was bitter about the MINIX/Linux history.
-- You are not a beautiful or unique snowflake -- but you could be if you got off your ass.
Re:Changed opinion
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pankajsethi
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· Score: 5, Insightful
I agree that a lot of people in academia have superinflated egos, but the ones who are at the top are because of their earnest desire to learn and explore new realms of their beloved fields. If Tannenbaum was narrow minded to get entangled in micro-kernel vs. macro-kernel, he wouldn't be where he is right now.
Remember that research is more about asking questions, engaging in discussions, acting as a devil's advocate to prove yourself wrong, and dealing paradoxes then it is about answering them. I'm sure nobody around here as any doubt about contribution Tannenbaum has made to computer sceience can be surpassed only by few.
He so totally rocks and has been my inspirtation since my undergrad days and has written a few books that I will never part with.
Re:Changed opinion
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dan_sdot
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· Score: 5, Insightful
You know, I think I had AST wrong. I'd seen the thread where he bashes Linus for not doing a microkernel design and thought that maybe it was sour grapes.
Well, its good that you made such an informed judgement on his character so early. I think that way to many/.ers are doing that. They read one thread that was linked to a couple days ago, and just because it was an argument with Linus, he must be the bad guy. Remember that, after all, he was being very polite in that discussion and in the end Linus had to apologize for being too hotheaded. He simply strongly believes that microkernels are the best approach.
So please,/.ers, stop thinking that you have to have an opinion on everything, even the things that you don't really know about.
Re:Changed opinion
by
be-fan
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· Score: 5, Insightful
Please, respond when you know what you are talking about.
Someone in an academic environment supposed to be open to idea's and non baised. Most though have ego's including Tanenbaum which blind them. Who said academics are supposed to be biased? Most are very biased towards their own ideas, and push them whenever possible. Its a natural part of the competitive system that allows academia to advance.
Funny, Linux, Solaris, FreeBSD, and As/400 have uptimes that measure in years if you do not include security patching. Even funnier is the fact that, with a microkernel OS, lots of downtime due to security-patching is unnecessary, because critical services run as easily restarted userspace tasks. There is no doubt that Linux, Solaris, *BSD, etc, are highly stable, but they are something you trust your server to --- a microkernel like QNX is what you trust your nuclear reactor to!
MacOSX is less stable than a macrokernels like Linux according to those who use it as a server. MacOS X has a monolithic kernel. Mach and BSD both run in kernel-space, with messaging replaced by direct function calls wherever possible. That was one of the chief changes between NeXTStep and OS X.
-- A deep unwavering belief is a sure sign you're missing something...
I read Linus' book and heard about the "feud" between him and Tanenbaum... somehow, I never connected that Tanenbaum to the one that wrote my networking text...
Whatever else may be said about Prof. Tanenbaum, I learned much of what I know about networking from his excellent text. It should be said that he is excellent at what he does (that is, teaching students about computers).
-- What we really need is a ten day waiting period and a background check before you can buy a congressman.
I resent that!
by
Anonymous Coward
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· Score: 5, Funny
Ken Brown is some guy who works for something called the "Alex de Torqueville" (sic?) institute and he's writing a book which appears to mostly consist of slander against Linus Tourvalds and/or the Free Software movement.
No it isn't, and I resent that! Slander is spoken. In print it's "Libel".
Sincerely,
Kenneth Brown President, Alexis de Tocqueville Institution
1600 come from search-engine bots
450 come from kids attempting to compromise his apache server with IIS-specific exploits
350 come from a single female grad student who is all aflutter over AST's [micro-kernel] hacking skills.
75 come from accidentally mis-spelling 'whitehouse.gov'
24 come from/. users
1 comes from his mother.
There is a difference, though it is often colored by the listener's own sense of self confidence.
In the spirit of AST's baseball analogy, I refer you to the immortal words of Dizzy Dean: " It ain't bragging if you can do it."
We should set up better Open Source Marketing
by
puntloos
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· Score: 5, Interesting
Trying not to troll here, but this document is not that news-worthy, is it? I mean -obviously- the whole Ken Brown thing is one big Microsoft Marketing Ploy (tm). If a manager 'falls for' (lets assume the Ken Brown book is purely Microsoft Marketing driven) the arguments of the book, he's probably not of the sort to go look for Andrew Tanenbaum's site. These people are the ones that fall for dicy logic (in this case, the "Argumentam ad Verecundiam", or argument from authority, fake or no, the institute sounds interesting)
On the same note, I doubt that very many in the 'Slashdot-like' internet community need extra convincing to believe that the book is Microsoft-driven, not fact-driven.
Therefore the only effect Tanenbaum (and Slashdot) gets from this document is self-defence and mutual knob-polishery. Not that Tanenbaum is entitled to have his say and defend his honor, but there you go.
What the Slashdot/unix/GNU/whatever community really should consider is how they can truely counter the 'lets convince the stupid masses' policy of Microsoft. (yeah I know I sound elitist, thats because I am..)
Seriously though, the more manager types that don't fall for Microsoft Marketing the better, IMHO. But how? I don't think slashdotting works, but perhaps we should set up a more Market-driven avocacy site for open source. Get The Facts! There are plenty of people out there who would have fun with doing some effective marketing here, and could do more for the community than program another random number generator;)
One of the things that strikes me most about Microsoft Marketing is that whatever Article (negative or no) I read online about Microsoft, 8 out of 10 times I see a big blinking Microsoft ad! I can't help but be impressed by that, even if I don't like it.
Re:Arrogance
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Anonymous Coward
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· Score: 5, Funny
Can't help it, but whenever I read something from Tanenbaum, I am thinking "oh my, is this guy arrogant".
Funny, I feel the same way when I read Slashdot.
Re:Linux is Obsolete
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dan_sdot
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· Score: 5, Insightful
So I guess Prof. Tanenbaum can give higher grade than "F" to Linus now.:)
Actually, I still don't think that he would. He still affirms that the point of view from which he looks at OS design is academic. He emphasizes that he is a PROFESSOR, not someone trying to make a production grade operating system. As are many academics, he is a purist and thus believes in a conceptually optimized design (microkernel) rather than a practical design (monolithic kernel). So, if Linus was still in his class, the "F" would probably stand, because Linux does not follow all the conceptual guidelines that Tanenbaum feels so strongly about. This argument was never really a big deal in the first place, it was just a classic arguemnt between a realist and a purist.
You're being way too fair to Microsoft. They bought a clone of CP/M ported to the 8086. Then, they sold a license for it to IBM.
In other words, they pretty much pulled a SCO, or at least SCO's stated intention at the outset of the current flurry of lawsuits.
-- HBI's Law: Frequency of calling others Nazis is directly correlated with the likelihood of the accuser being Communist.
Re:His comment on Slashdot:
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pankajsethi
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· Score: 5, Interesting
I'm not trying to make a hero out of AST, but he has been one of the most influential person in computer science. Not only has he contributed in terms of his creative input, but his bigger contribution is in teaching. His book on Computer Networks inspired me to write one myself.
Have you ever met Tanenbaum? Can you say that somebody is a "prick" just because he is willing to engage in a discussion solely on the basis of technical merits and because he loves one thing and hates another. I'll at least meet the person before debunking him as an egotist.
And Tanenbaum's achievements go beyond Minix. You can find out more if you care to look for his contributions on the web. He doesn't even count Minix as his achievement. The world does not know him for Minix. It was just a nice "add-on" to his operating book.
Have a good day.
I have the PDF of the first 92 pages of the book
by
ValourX
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· Score: 5, Interesting
... you guys would absolutely not believe the stuff this guy says about Free Software philosophy. He takes every single aspect of FOSS and gives it a sinister anti-business anti-America anti-puppy connotation.
I only read the first 20 pages or so, then I skipped to the bibliography. In over fifty listings, the only real books he listed were ESR's and they're available online. Every other reference he listed was someone's personal homepage or a newsgroup posting or something arbitrary like that.
There will be an article, ladies and gentlemen. I just haven't decided if it should be a serious analytical debunking of this troll book or a humor piece that shows its rediculousness.
-Jem
Re:His comment on Slashdot:
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Luzumsuz+Lazim
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· Score: 5, Interesting
Minix... wasn't really good for learning the architecture of an OS.... and people could goof around with it for free
I think, if a professor of mine would write an operating system for me to have me the freedom of goofing around, I would call it a very good source.
And, even if the OS itself was not so good, it doesn't matter, because people often learn the subject from the mistakes, shortcomings. After all, Linus wrote the Linux to improve Minix on Minix.
Re:His comment on Slashdot:
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kfg
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· Score: 5, Insightful
I'm posting this as AC since I'll most likely be modded down for touching a "hero" of the Linux revolution:
I've always rather gotten the impression that he was something of the anti-christ of the Linux revolution, and that that's why he has to waste so much time explaining that he and Linus are not enemies.
. ..very very pleased with himself for having written Minix and fostered the development of Linux.
And says so in the very paper in question.
The trouble is that Minix, which was meant to be an academic OS to study. ..
And says so in the very paper in question.
. ..was never good performance-wise. ..
And says so in the very paper in question.
. ..and wasn't really good for learning the architecture of an OS either.
Here I'm sure he'd disagree with you, however, since you leave out why it "wasn't really good" you protect yourself from criticism.
Minix knew success because it was "this other, free Unix for i386" (and some other architectures like the Atari ST), and people could goof around with it for free.
And says so in both papers in question.
That's the extent of Tanenbaum's achievenemts.
And explains that such is not the case in the paper in question.
. ..but somehow Tanenbaum feels entitled to think of himself as a pillar of computer science and computer history, and act accordingly.
And not only says so in the paper in question, but points to references should one chose to follow them up. Not to mention the fact that if he were not popularly regarded as such among the computer science community said paper whould have no had raison d'etre in the first place.
Now I shall watch myself be modded down as a troll by Slashdotter who have never met, read about, or listened to him...
As a general rule I find it more responsive to posts such as yours to, well, respond, rather than mod down something just because I might find it unpalatable. An unpalatable point of view is not the same thing as a troll.
I have never met the man, nor listened to him, but I have both read him and read about him. He is a public figure in the computer science community, just as is Linus.
He impresses me, as he appears to impress the orginal poster, as just the sort of intelligently sarcastic "prick," in the Swift/Dickens/Twain/Leacock mode, that I rather enjoy dealing with.
Of course you have to consider the source of that last statement (as one might well consider the source of any), as I myself have been accused, on occasion, of being such a man, and may be merely feeling an affinity of kind.
KFG
Re:His comment on Slashdot:
by
Coz
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· Score: 5, Interesting
I never had him, but my favorite undergrad CS professor LOVED using his books - he would say "Here's where Tannenbaum got it right" and riff for five minutes, then say "And here's where he blew it, and this is why" and be off for fifteen... I enjoyed Tobin's classes, and I'm not sure he'd've been nearly as much fun without AST's textbooks to use as a basis. I've been through Compilers, Computer Networks, and two Operating Systems classes using Tannenbaum's books, (and many since using books by others), and I can say they were all bona-fide Learning Experiences.
Back then (way back in the late '80s), standard assignments were to go "tweak" parts of Minix - make the network interface big- or little-endian, switchable on the fly; change the file system block size and see what happens; screw up the priority system and see if user keypresses even get answered before your applications finish running... as a learning OS, demonstrating ways OSs can be put together, I learned a lot from it.
Then we got into compilers... *sigh*
-- I love vegetarians - some of my favorite foods are vegetarians.
Re:His comment on Slashdot:
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mst76
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· Score: 5, Insightful
> I'll most likely be modded down for touching a "hero" of the Linux revolution:
Tanenbaum is hardly seen as a "hero" in the Linux community, of those who know him at all, most only remember the infamous "Linux is obsolete" flameware on Usenet.
> It's quite well known that Proff Tanenbaum is somewhat of a prick, very very pleased with himself for having written Minix and fostered the development of Linux.
How is this well known? I've never read anything about him boasting about having fostered the development of Linux. He does point out areas where the early Linux was inspired by Minix, but I don't think anyone would dispute that.
> Minix knew success because it was "this other, free Unix for i386"
It was the "free Unix for XT". One of the reasons for Linus to develop Linux was that Minix didn't take advantage of any of the advanced features of the 80386. AST refused almost all suggested improvements, his motivation being that he wanted to teach it in a one semester course.
> That's the extent of Tanenbaum's achievenemts.
Tanenbaum is a university professor. His achievements are his publications in peer reviewed journals, and citations to these publications. Since he has lots of both, he's been pretty successful.
Re:His comment on Slashdot:
by
1iar_parad0x
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· Score: 5, Interesting
While I'm hardly a Linux zealot, I think Tanenbaum deserves quite a bit of credit. Tanenbaum's books are hands on. I'm not a CS major anymore; I'm a math major, so I don't claim to be up on every OS textbook in the field. However, I still like to get my hands dirty with interesting code and I've been a programmer professionally for several years.
I don't know Tanenbaum at all; however, his books are more hands on than the standard fare. My OS book didn't come with any usable code at all. Frankly, I had to force code into my class. In fact, my professor (old to the computer industry, but young to academia) was prompted to bring more required labs to the class because of it. I've picked up a few of Tanenbaum's books. In my opinion, it's as good at teaching operating systems as the "dragon" book is on teaching compiler design.
Why is Richard Stevens considered a genius and Tanenbaum not. Humility aside, like I said I never met the guy, most professors are a little bit pompous. As long as he doesn't torture his students with such BS, a little arrogance is fine by me. Including a small copy of a Unix-like variant to be examined with the book was revolutionary by pedagogical standards. I once had a copy of the "Lions Commentary on Unix". While it was interesting, it was written in C and Assembly (with some antiquated instruction set)**. The code was virtually useless for me. Despite popular opinion, I really don't have a PDP-11 in my basement. Tanenbaum's book|code was great. Finally a useful OS I could "play" with. Linux is too large to examine in a classroom. It's an industrial strength OS. Should I learn database theory by mucking with the source code for Oracle or DB2 (if this were even possible)? Of course not. Why should an OS be any different? You only learn by doing. You don't really learn by thinking about psuedocode. In this regard, MINIX fills a hole so desperately apparent in academia. MINIX provides a tangible example of modern OS design.
If you've had this man for a class and can relate a specific instance about his arrogance, feel free to do so. That's a completely different story. However, if you're going to knock the man for having some pride in his work -- well tough. It's not like Bill Gates, Steve Jobs, Gary Killdall, et al isn't a little bit of a "prick" too.
**I don't remember too much about the specifics of the "Lions Commentary on Unix".
-- What do you mean my sig is repetitive? What do you mean my sig is repetitive? What do you mean....
Re:Little Help?
by
nathanh
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· Score: 5, Insightful
Who is Professor Tanenbaum? Who is Ken Brown?
Tanenbaum (AST) is a Professor who worked at AT&T and has written many textbooks aimed at university students. AST's most famous book - Operating Systems: Design and Implementation - includes a UNIX-alike operating system called Minix that he wrote himself. Minix includes binaries and source code for the kernel, C library, C compiler, and all the utilities. AST wrote Minix and the book to teach students how operating systems are written. Any computing science student who attended a decent university in the past decade has probably had at least one of AST's books as a required text.
Minix ran on an 8086 and didn't have modern virtual memory (VM) features. When the 80386 came out there were some unofficial patches to make Minix/386. These patches added virtual memory and paging and memory protection, turning Minix into an useful OS. AST refused to add these patches to Minix, rightly arguing that they would make Minix too complex for a student to understand. Minix was a teaching tool, not a general purpose OS, even though Minix/386 was a pretty good general purpose OS. Unfortunately the license back then didn't permit forking. Despite these limitations, Minix had a very large user community. .
When Linus came along and announced Linux a lot of people realised that GNU (basically all of UNIX except for the kernel) and Linux (basically none of UNIX except the kernel) when combined would produce a UNIX-alike operating system. Just like Minix but with VM and the more relaxed GPL for a license. There was no Linux news group so all the discussions were on the Minix news group.
AST put his two cents in on the Linux kernel. He correctly pointed out that the Linux design was a 30 year old monolithic design; not elegant or modern. Linus argued back that monolithic kernels are more practical. AST said Linus would fail his OS class, if Linus was his student. That's the infamous AST/Linus flamewar. It wasn't very hot, as far as flamewars went. AST was right, so was Linus. They just had different perspectives.
Ken Brown is an ignorant idiot who is selling a book claiming that Linus didn't write Linux. He argues that noone could write something so complex as a UNIX-like kernel without stealing code. Ken is under the delusion that writing a UNIX needs a huge team of people working for many years. He seems to be ignorant of the fact that the first UNIX was written by Ken Thompson on a computer so ancient that your wrist watch has more computing power. For "research", Ken Brown spoke to AST. Notably he did not speak to Linus Torvalds. AST is pointing out that Ken is lying in his book; AST has pointed to several examples of single authors who created a UNIX-like kernel, AST included.
The confusion might be that Ken Brown doesn't understand that Linux is just a kernel. The first "Linux" that you ran back in 1991 was actually GNU/Linux. Linux comprised less than 2% of that system. RMS and his team had been working on GNU for nearly a decade by that stage (longer if you count emacs). Linux The Kernel was a small piece of the puzzle. An essential piece, but certainly writable in 6 months by a bright and talented person. These days, Linux is an incredibly tiny piece of a "Linux distribution". Ken Brown might think that Linus is laying claim to the entire system. Of course, Linus has only ever claimed credit for the first kernel. Recent kernels have very little "Linus" in them. And the distro you have on the desktop is less than 1% Linux anyway.
The other theory is that Ken Brown is being paid by SCO/Microsoft/LatestPariah to create FUD over the legal origins of Linux.
I prefer my own theory. Ken wants attention. Saying something ridiculous gets easy attention and increases book sales. We're playing right into his hands by giving him the time of day. It gives him false credibility by creating a "controversy" when in reality there is no controversy. Just Ken saying ridiculous things with no evidence to back them up. It's like all those authors who write books on Noah's Ark, or the location of Atlantis. They must have a huge grin on their face when somebody pays attention to them.
Microkernel reality
by
Animats
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· Score: 5, Informative
For starters, I'm reading this discussion on a computer running a microkernel. This machine is running QNX 6.2 on a Shuttle 1.5GHz AMD desktop box. The browser is Mozilla 1.6, running under the QNX Photon GUI. It runs about as well as the same version of Mozilla on a comparable Windows machine. Even the same Mozilla bugs show up.
The file systems and networking are user programs.
You can add new file systems; there's one that mounts.zip files, there's NFS, and there's Samba.
In Linux terms, visualize a system where there's the/proc file system for inter-program communication, and everything works through that mechanism.
The drivers really are outside the OS. I've written a FireWire camera driver for QNX, and it's a user program. It's privileged in that it does map some real memory shared by the device, and it can talk to the device directly, so it could potentially cause a crash by making the device write someplace it shouldn't. (That's really a weakness in the PC's I/O architecture; there's no MMU between devices
and memory, for historical reasons dating back to the original IBM PC.)
Debugging a driver is like debugging a normal program. You can even run a driver under a debugger. You can kill a driver while it's running, and it's no big deal. (If you have real memory mapped, it's not recovered until the next boot, so I had to restart my machine about once a week while doing driver development.) Mainframe people have been doing this since the 1960s, but it's rare on PCs.
The basic penalty for using a microkernel is one extra copy and context switch for every file system operation. If your system is doing anything besides I/O, you'll probably never notice. If you're running a web server that serves mostly plain pages (little Perl, Java, PHP, etc.),
you'd probably notice the overhead.
So why are microkernels so rare? They're hard to write well. You can't just hack them together like a UNIX clone. There are some tough design problems to be solved. If those are botched, message passing performance will be terrible.
Message passing and CPU scheduling need to work together. This forces certain design decisions in the scheduler. It's also why adding message passing to an existing system tends not to work well. The Hurd crowd has been thrashing on this issue for a decade. I would have loved to see something as good as QNX from the Hurd people.
But it didn't happen.
Mach didn't really work out as a microkernel. Mach started from 4.3BSD (considered bloated in its day), and versions of Mach below 3 had 4.3BSD in the kernel. MacOS X is not a microkernel system; the BSD stuff is in the kernel. Basically, retrofitting a microkernel architecture to an existing UNIX kernel didn't work.
What you do get from a microkernel like QNX is predictablity. The kernel changes very little and is very reliable. Good microkernels, like QNX and IBM's VM, settle down into versions that almost never change and have very long MTBFs. This brings down total cost of ownership.
Re: microkernels the best approach
by
niew
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· Score: 5, Informative
If you want successful microkernels, look at NT and Darwin
Hmmm, No...
It's a widely perpetuated myth that NT is a microkernel. It may have started out that way, but has long since grown through millikernel, centikernel, decikernel to full blown kernel... (and beyond if you count browser, media player and kitchen sink OS embedding)
The linked letter from Prof Tanenbaum touches on this point too... He says:
Microsoft claimed that Windows NT 3.51 was a microkernel. It wasn't. It wasn't even close. Even they dropped the claim with NT 4.0.
I've had him as a professor
by
tmgtmgtmg
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· Score: 5, Interesting
I think I like this guy. Has anyone here ever had him as a professor? Is he this amusing when he's teaching class?:)
I've had him as a professor and he co-advised my Master's thesis.
Indeed, he is as amusing when teaching class. I took one or two classes he taught. However, his lectures are useless because his books speak for themselves. The only real reason to go to his lectures is because he is very funny.
In addition to the lectures, we had to modify the MINIX kernel to do memory fragmentation and modify the file system to support ACLs. Both not very hard, but a good learning experience.
I know he's always on the lookout for graduate students to work with him. Having had him co-advise my Master's thesis, I can wholeheartedly encourage you to work with Prof. Tanenbaum.
Slashdot Mirror
Ken Brown's Motivation, Release 1.2
Background
On 20 May 2004, I posted a statement refuting the claim of Ken Brown, President of the Alexis de Tocqueville Institution, that Linus Torvalds didn't write Linux. My statement was mentioned on Slashdot, Groklaw, and many other Internet news sites. This attention resulted in over 150,000 requests to our server in less than a day, which is still standing despite yesterday being a national holiday with no one there to stand next to it saying "You can do it. You can do it." Kudos to Sun Microsystems and the folks who built Apache. My statement was mirrored all over the Internet, so the number of true hits to it is probably a substantial multiple of that. There were also quite a few comments at Slashdot, Groklaw, and other sites, many of them about me. I had never engaged in remote multishrink psychoanalysis on this scale before, so it was a fascinating experience.
The Brown Book
I got an advance copy of Ken Brown's book. I think it is still under embargo, so I won't comment on it. Although I am not an investigative reporter, even I know it is unethical to discuss publications still under embargo. Some of us take ethics more seriously than others. So I won't even reveal the title. Let's call it The Brown Book. There is some precedent for nicknaming books after colors: The International Standard for the CD-ROM (IS 10149) is usually called The Red Book.
Suffice it to say, there is a great deal to criticize in the book. I am sure that will happen when it is published. I may even help out.
Brown's Motivation
What prompted me to write this note today is an email I got yesterday. Actually, I got quite a few :-) , most of them thanking me for the historical material. One of yesterday's emails was from Linus, in response to an email from me apologizing for not letting him see my statement in advance. As a matter of courtesy, I did try but I was using his old transmeta.com address and didn't know his new one until I got a very kind email from Linus' father, a Finnish journalist.
In his email, Linus said that Brown never contacted him. No email, no phone call, no personal interview. Nothing. Considering the fact that Brown was writing an explosive book in which he accused Linus of not being the author of Linux, you would think a serious author would at least confront the subject with the accusation and give him a chance to respond. What kind of a reporter talks to people on the periphery of the subject but fails to talk to the main player?
Why did Brown fly all the way to Europe to interview me and (and according to an email I got from his seat-mate on the plane) one other person in Scandinavia, at considerable expense, and not at least call Linus? Even if he made a really bad choice of phone company, how much could that cost? Maybe a dollar? I call the U.S. all the time from Amsterdam. It is less than 5 cents a minute. How much could it cost to call California from D.C.?
From reading all the comments posted yesterday, I am now beginning to get the picture. Apparently a lot of people (still) think that I 'hate' Linus for stealing all my glory (see below for more on this). I didn't realize this view was so widespread. I now suspect that Brown believed this, too, and thought that I would be happy to dump all over Linus to get 'revenge.' By flying to Amsterdam he thought he could dig up dirt on Linus and get me to speak evil of him. He thought I would back up his crazy claim that Linus stole Linux from me. Brown was wrong on two counts. First, I bear no 'grudge' against Linus at all. He wrote Linux himself and deserves the credit. Second, I am really not a mean person. Even if I were still angry with him aft
Just when he thought it was over, here we come for another round. . .
Some of which are easier to answer than others:
Why did Brown fly all the way to Europe to interview me and (and according to an email I got from his seat-mate on the plane) one other person in Scandinavia, at considerable expense, and not at least call Linus?
I think the answer is "because calling Linus wouldn't have allowed Brown to get the Alex de Torqeville Institute to pay for him to take a vacation to Holland".
There is no other way to explain the conclusions we've seen reported for this book, except that Brown spent a good deal of time in Amsterdam coffeehouses, consuming high-grade grass.
It was a joke! When you give me that look it was a joke.
You know, I think I had AST wrong. I'd seen the thread where he bashes Linus for not doing a microkernel design and thought that maybe it was sour grapes.
His exchanges on this subject have changed my opinion on that. He's been nothing but kind toward Linus, generous with his time, and well-spoken.
If anything good come out of this whole mess, maybe it's that AST really got to show us what he's really like instead of all of us just assuming that he was bitter about the MINIX/Linux history.
You are not a beautiful or unique snowflake -- but you could be if you got off your ass.
I read Linus' book and heard about the "feud" between him and Tanenbaum... somehow, I never connected that Tanenbaum to the one that wrote my networking text...
Whatever else may be said about Prof. Tanenbaum, I learned much of what I know about networking from his excellent text. It should be said that he is excellent at what he does (that is, teaching students about computers).
What we really need is a ten day waiting period and a background check before you can buy a congressman.
...by getting slashdotted again!
Please help metamoderate.
Ken Brown is some guy who works for something called the "Alex de Torqueville" (sic?) institute and he's writing a book which appears to mostly consist of slander against Linus Tourvalds and/or the Free Software movement.
No it isn't, and I resent that! Slander is spoken. In print it's "Libel".
Sincerely,
Kenneth Brown
President, Alexis de Tocqueville Institution
Examining his home-page hit rate:
/. users
1600 come from search-engine bots
450 come from kids attempting to compromise his apache server with IIS-specific exploits
350 come from a single female grad student who is all aflutter over AST's [micro-kernel] hacking skills.
75 come from accidentally mis-spelling 'whitehouse.gov'
24 come from
1 comes from his mother.
There is a difference, though it is often colored by the listener's own sense of self confidence.
In the spirit of AST's baseball analogy, I refer you to the immortal words of Dizzy Dean: " It ain't bragging if you can do it."
On the same note, I doubt that very many in the 'Slashdot-like' internet community need extra convincing to believe that the book is Microsoft-driven, not fact-driven.
Therefore the only effect Tanenbaum (and Slashdot) gets from this document is self-defence and mutual knob-polishery. Not that Tanenbaum is entitled to have his say and defend his honor, but there you go.
What the Slashdot/unix/GNU/whatever community really should consider is how they can truely counter the 'lets convince the stupid masses' policy of Microsoft. (yeah I know I sound elitist, thats because I am..)
Seriously though, the more manager types that don't fall for Microsoft Marketing the better, IMHO. But how? I don't think slashdotting works, but perhaps we should set up a more Market-driven avocacy site for open source. Get The Facts! There are plenty of people out there who would have fun with doing some effective marketing here, and could do more for the community than program another random number generator ;)
One of the things that strikes me most about Microsoft Marketing is that whatever Article (negative or no) I read online about Microsoft, 8 out of 10 times I see a big blinking Microsoft ad! I can't help but be impressed by that, even if I don't like it.
Funny, I feel the same way when I read Slashdot.
This argument was never really a big deal in the first place, it was just a classic arguemnt between a realist and a purist.
You're being way too fair to Microsoft. They bought a clone of CP/M ported to the 8086. Then, they sold a license for it to IBM.
In other words, they pretty much pulled a SCO, or at least SCO's stated intention at the outset of the current flurry of lawsuits.
HBI's Law: Frequency of calling others Nazis is directly correlated with the likelihood of the accuser being Communist.
I'm not trying to make a hero out of AST, but he has been one of the most influential person in computer science. Not only has he contributed in terms of his creative input, but his bigger contribution is in teaching. His book on Computer Networks inspired me to write one myself.
Have you ever met Tanenbaum? Can you say that somebody is a "prick" just because he is willing to engage in a discussion solely on the basis of technical merits and because he loves one thing and hates another. I'll at least meet the person before debunking him as an egotist.
And Tanenbaum's achievements go beyond Minix. You can find out more if you care to look for his contributions on the web. He doesn't even count Minix as his achievement. The world does not know him for Minix. It was just a nice "add-on" to his operating book.
Have a good day.
... you guys would absolutely not believe the stuff this guy says about Free Software philosophy. He takes every single aspect of FOSS and gives it a sinister anti-business anti-America anti-puppy connotation.
I only read the first 20 pages or so, then I skipped to the bibliography. In over fifty listings, the only real books he listed were ESR's and they're available online. Every other reference he listed was someone's personal homepage or a newsgroup posting or something arbitrary like that.
There will be an article, ladies and gentlemen. I just haven't decided if it should be a serious analytical debunking of this troll book or a humor piece that shows its rediculousness.
-Jem
I think, if a professor of mine would write an operating system for me to have me the freedom of goofing around, I would call it a very good source.
And, even if the OS itself was not so good, it doesn't matter, because people often learn the subject from the mistakes, shortcomings. After all, Linus wrote the Linux to improve Minix on Minix.
I'm posting this as AC since I'll most likely be modded down for touching a "hero" of the Linux revolution:
.very very pleased with himself for having written Minix and fostered the development of Linux.
.
.was never good performance-wise. . .
.and wasn't really good for learning the architecture of an OS either.
.but somehow Tanenbaum feels entitled to think of himself as a pillar of computer science and computer history, and act accordingly.
I've always rather gotten the impression that he was something of the anti-christ of the Linux revolution, and that that's why he has to waste so much time explaining that he and Linus are not enemies.
. .
And says so in the very paper in question.
The trouble is that Minix, which was meant to be an academic OS to study. .
And says so in the very paper in question.
. .
And says so in the very paper in question.
. .
Here I'm sure he'd disagree with you, however, since you leave out why it "wasn't really good" you protect yourself from criticism.
Minix knew success because it was "this other, free Unix for i386" (and some other architectures like the Atari ST), and people could goof around with it for free.
And says so in both papers in question.
That's the extent of Tanenbaum's achievenemts.
And explains that such is not the case in the paper in question.
. .
And not only says so in the paper in question, but points to references should one chose to follow them up. Not to mention the fact that if he were not popularly regarded as such among the computer science community said paper whould have no had raison d'etre in the first place.
Now I shall watch myself be modded down as a troll by Slashdotter who have never met, read about, or listened to him...
As a general rule I find it more responsive to posts such as yours to, well, respond, rather than mod down something just because I might find it unpalatable. An unpalatable point of view is not the same thing as a troll.
I have never met the man, nor listened to him, but I have both read him and read about him. He is a public figure in the computer science community, just as is Linus.
He impresses me, as he appears to impress the orginal poster, as just the sort of intelligently sarcastic "prick," in the Swift/Dickens/Twain/Leacock mode, that I rather enjoy dealing with.
Of course you have to consider the source of that last statement (as one might well consider the source of any), as I myself have been accused, on occasion, of being such a man, and may be merely feeling an affinity of kind.
KFG
I never had him, but my favorite undergrad CS professor LOVED using his books - he would say "Here's where Tannenbaum got it right" and riff for five minutes, then say "And here's where he blew it, and this is why" and be off for fifteen... I enjoyed Tobin's classes, and I'm not sure he'd've been nearly as much fun without AST's textbooks to use as a basis. I've been through Compilers, Computer Networks, and two Operating Systems classes using Tannenbaum's books, (and many since using books by others), and I can say they were all bona-fide Learning Experiences.
Back then (way back in the late '80s), standard assignments were to go "tweak" parts of Minix - make the network interface big- or little-endian, switchable on the fly; change the file system block size and see what happens; screw up the priority system and see if user keypresses even get answered before your applications finish running... as a learning OS, demonstrating ways OSs can be put together, I learned a lot from it.
Then we got into compilers... *sigh*
I love vegetarians - some of my favorite foods are vegetarians.
> I'll most likely be modded down for touching a "hero" of the Linux revolution:
Tanenbaum is hardly seen as a "hero" in the Linux community, of those who know him at all, most only remember the infamous "Linux is obsolete" flameware on Usenet.
> It's quite well known that Proff Tanenbaum is somewhat of a prick, very very pleased with himself for having written Minix and fostered the development of Linux.
How is this well known? I've never read anything about him boasting about having fostered the development of Linux. He does point out areas where the early Linux was inspired by Minix, but I don't think anyone would dispute that.
> Minix knew success because it was "this other, free Unix for i386"
It was the "free Unix for XT". One of the reasons for Linus to develop Linux was that Minix didn't take advantage of any of the advanced features of the 80386. AST refused almost all suggested improvements, his motivation being that he wanted to teach it in a one semester course.
> That's the extent of Tanenbaum's achievenemts.
Tanenbaum is a university professor. His achievements are his publications in peer reviewed journals, and citations to these publications. Since he has lots of both, he's been pretty successful.
While I'm hardly a Linux zealot, I think Tanenbaum deserves quite a bit of credit. Tanenbaum's books are hands on. I'm not a CS major anymore; I'm a math major, so I don't claim to be up on every OS textbook in the field. However, I still like to get my hands dirty with interesting code and I've been a programmer professionally for several years.
I don't know Tanenbaum at all; however, his books are more hands on than the standard fare. My OS book didn't come with any usable code at all. Frankly, I had to force code into my class. In fact, my professor (old to the computer industry, but young to academia) was prompted to bring more required labs to the class because of it. I've picked up a few of Tanenbaum's books. In my opinion, it's as good at teaching operating systems as the "dragon" book is on teaching compiler design.
Why is Richard Stevens considered a genius and Tanenbaum not. Humility aside, like I said I never met the guy, most professors are a little bit pompous. As long as he doesn't torture his students with such BS, a little arrogance is fine by me. Including a small copy of a Unix-like variant to be examined with the book was revolutionary by pedagogical standards. I once had a copy of the "Lions Commentary on Unix". While it was interesting, it was written in C and Assembly (with some antiquated instruction set)**. The code was virtually useless for me. Despite popular opinion, I really don't have a PDP-11 in my basement. Tanenbaum's book|code was great. Finally a useful OS I could "play" with. Linux is too large to examine in a classroom. It's an industrial strength OS. Should I learn database theory by mucking with the source code for Oracle or DB2 (if this were even possible)? Of course not. Why should an OS be any different? You only learn by doing. You don't really learn by thinking about psuedocode. In this regard, MINIX fills a hole so desperately apparent in academia. MINIX provides a tangible example of modern OS design.
If you've had this man for a class and can relate a specific instance about his arrogance, feel free to do so. That's a completely different story. However, if you're going to knock the man for having some pride in his work -- well tough. It's not like Bill Gates, Steve Jobs, Gary Killdall, et al isn't a little bit of a "prick" too.
**I don't remember too much about the specifics of the "Lions Commentary on Unix".
What do you mean my sig is repetitive? What do you mean my sig is repetitive? What do you mean....
Tanenbaum (AST) is a Professor who worked at AT&T and has written many textbooks aimed at university students. AST's most famous book - Operating Systems: Design and Implementation - includes a UNIX-alike operating system called Minix that he wrote himself. Minix includes binaries and source code for the kernel, C library, C compiler, and all the utilities. AST wrote Minix and the book to teach students how operating systems are written. Any computing science student who attended a decent university in the past decade has probably had at least one of AST's books as a required text.
Minix ran on an 8086 and didn't have modern virtual memory (VM) features. When the 80386 came out there were some unofficial patches to make Minix/386. These patches added virtual memory and paging and memory protection, turning Minix into an useful OS. AST refused to add these patches to Minix, rightly arguing that they would make Minix too complex for a student to understand. Minix was a teaching tool, not a general purpose OS, even though Minix/386 was a pretty good general purpose OS. Unfortunately the license back then didn't permit forking. Despite these limitations, Minix had a very large user community. .
When Linus came along and announced Linux a lot of people realised that GNU (basically all of UNIX except for the kernel) and Linux (basically none of UNIX except the kernel) when combined would produce a UNIX-alike operating system. Just like Minix but with VM and the more relaxed GPL for a license. There was no Linux news group so all the discussions were on the Minix news group.
AST put his two cents in on the Linux kernel. He correctly pointed out that the Linux design was a 30 year old monolithic design; not elegant or modern. Linus argued back that monolithic kernels are more practical. AST said Linus would fail his OS class, if Linus was his student. That's the infamous AST/Linus flamewar. It wasn't very hot, as far as flamewars went. AST was right, so was Linus. They just had different perspectives.
Ken Brown is an ignorant idiot who is selling a book claiming that Linus didn't write Linux. He argues that noone could write something so complex as a UNIX-like kernel without stealing code. Ken is under the delusion that writing a UNIX needs a huge team of people working for many years. He seems to be ignorant of the fact that the first UNIX was written by Ken Thompson on a computer so ancient that your wrist watch has more computing power. For "research", Ken Brown spoke to AST. Notably he did not speak to Linus Torvalds. AST is pointing out that Ken is lying in his book; AST has pointed to several examples of single authors who created a UNIX-like kernel, AST included.
The confusion might be that Ken Brown doesn't understand that Linux is just a kernel. The first "Linux" that you ran back in 1991 was actually GNU/Linux. Linux comprised less than 2% of that system. RMS and his team had been working on GNU for nearly a decade by that stage (longer if you count emacs). Linux The Kernel was a small piece of the puzzle. An essential piece, but certainly writable in 6 months by a bright and talented person. These days, Linux is an incredibly tiny piece of a "Linux distribution". Ken Brown might think that Linus is laying claim to the entire system. Of course, Linus has only ever claimed credit for the first kernel. Recent kernels have very little "Linus" in them. And the distro you have on the desktop is less than 1% Linux anyway.
The other theory is that Ken Brown is being paid by SCO/Microsoft/LatestPariah to create FUD over the legal origins of Linux.
I prefer my own theory. Ken wants attention. Saying something ridiculous gets easy attention and increases book sales. We're playing right into his hands by giving him the time of day. It gives him false credibility by creating a "controversy" when in reality there is no controversy. Just Ken saying ridiculous things with no evidence to back them up. It's like all those authors who write books on Noah's Ark, or the location of Atlantis. They must have a huge grin on their face when somebody pays attention to them.
The file systems and networking are user programs. You can add new file systems; there's one that mounts .zip files, there's NFS, and there's Samba.
In Linux terms, visualize a system where there's the /proc file system for inter-program communication, and everything works through that mechanism.
The drivers really are outside the OS. I've written a FireWire camera driver for QNX, and it's a user program. It's privileged in that it does map some real memory shared by the device, and it can talk to the device directly, so it could potentially cause a crash by making the device write someplace it shouldn't. (That's really a weakness in the PC's I/O architecture; there's no MMU between devices and memory, for historical reasons dating back to the original IBM PC.)
Debugging a driver is like debugging a normal program. You can even run a driver under a debugger. You can kill a driver while it's running, and it's no big deal. (If you have real memory mapped, it's not recovered until the next boot, so I had to restart my machine about once a week while doing driver development.) Mainframe people have been doing this since the 1960s, but it's rare on PCs.
The basic penalty for using a microkernel is one extra copy and context switch for every file system operation. If your system is doing anything besides I/O, you'll probably never notice. If you're running a web server that serves mostly plain pages (little Perl, Java, PHP, etc.), you'd probably notice the overhead.
So why are microkernels so rare? They're hard to write well. You can't just hack them together like a UNIX clone. There are some tough design problems to be solved. If those are botched, message passing performance will be terrible. Message passing and CPU scheduling need to work together. This forces certain design decisions in the scheduler. It's also why adding message passing to an existing system tends not to work well. The Hurd crowd has been thrashing on this issue for a decade. I would have loved to see something as good as QNX from the Hurd people. But it didn't happen.
Mach didn't really work out as a microkernel. Mach started from 4.3BSD (considered bloated in its day), and versions of Mach below 3 had 4.3BSD in the kernel. MacOS X is not a microkernel system; the BSD stuff is in the kernel. Basically, retrofitting a microkernel architecture to an existing UNIX kernel didn't work.
What you do get from a microkernel like QNX is predictablity. The kernel changes very little and is very reliable. Good microkernels, like QNX and IBM's VM, settle down into versions that almost never change and have very long MTBFs. This brings down total cost of ownership.
Hmmm, No...
It's a widely perpetuated myth that NT is a microkernel. It may have started out that way, but has long since grown through millikernel, centikernel, decikernel to full blown kernel... (and beyond if you count browser, media player and kitchen sink OS embedding)
The linked letter from Prof Tanenbaum touches on this point too... He says:
I've had him as a professor and he co-advised my Master's thesis.
Indeed, he is as amusing when teaching class. I took one or two classes he taught. However, his lectures are useless because his books speak for themselves. The only real reason to go to his lectures is because he is very funny.
In addition to the lectures, we had to modify the MINIX kernel to do memory fragmentation and modify the file system to support ACLs. Both not very hard, but a good learning experience.
I know he's always on the lookout for graduate students to work with him. Having had him co-advise my Master's thesis, I can wholeheartedly encourage you to work with Prof. Tanenbaum.