Interview with Kernel Hacker Robert Love

An anonymous reader writes: "An interview with the ever interesting Robert Love is at KernelTrap. Robert is author of the kernel preemption patch which has been merged into the 2.5 development kernel. In this interview, Robert discusses the status of Linux kernel preemption, talks about his recent involvement with the O(1) scheduler and explains his recent VM overcommit work. He also reflects upon Linus' use of Bitkeeper, the future of Linux, and the recent Kernel Summit in Ottawa. A Good Read."

Comments

Re:what's with all these hippies?

[reverius]

I can see where you got "Dick" Stallman from, but surely you meant "Eric" Raymond? His name isn't Ed, y'know... (or Edward, or Edmond/Edmund, or Eduardo)

Richard == Dick

Eric != Ed

See how that works? :)

Can someone explain the preemptible kernel?

[extrasolar]

I don't spend a lot of time thinking about the kernel, I'm more interested in other areas.

Is there a link or something explaining what a preemptible kernel is?

Re:Can someone explain the preemptible kernel?

[4of12]

I'm not a kernel developer, either, but I have just enough ignorance to be dangerous....

AFAICT, if you have some process that's really gotta run, then you don't even want the kernel taking up valuable slices of time because of the potential impact on performance. Hence, allow your process to be effectively negatively niced beyond what is possible without the preemption patch.

I think some purists would argue that you might as well just start using a Real Time version of the kernel in that case. But I think that real time requirements can cause you to lose other good things that you might want to have around.

I've heard anecdotes that using the preemption patch and running X with an effective high priority makes things seem snappier for desktop use. Of course, there are probably plenty of potential applications in the server arena as well.

[I apologize to people that know what's really going on since I only know Jack Shit by reputation.]

Re:Can someone explain the preemptible kernel?

[Lionel Hutts]

It was discussed here. Briefly, it means that the kernel itself, just like user programs, can be preempted, preventing high latency.

The alternative, of course, is just to attack all sources of latency in the kernel, which should be both better and harder.

Hacker question

[Shadow Wrought]

I tend to read slashdot more for the Science and Sci-fi related nerd stuff, and am not real familiar with the programming world. I know the media uses the phrase "hacker" in a negative context, but "Kernel Hacker" seems very positive. Can anyone enlighten as to the appropriate use of "hacker"? Is this another example of the media creating its own connotations?

Re:Hacker question

[Trevelyan]

Hacker (white hats) codes for the good of (wo)man kind ;-)
whether thats coding (hacking) a program (or a kernel) or breaking into a remote machine AND then sending the admin of said machine info about the hack (eg how was done, maybe how to fix). hackers can get paid to do this!

Crackers (black hats) just likes to go round and break stuff, and is almost always what the media mean when they say hacker.

this is just my view, others may differ

Re:Hacker question

[mkanoap]

You may want to check out the definition in the jargon file. In fact, you may want to peruse the whole jargon file to get a handle on this slippery concept.

For those too lazy to follow the link, here is the definition (minus all the crossreferences):

hacker n.

[originally, someone who makes furniture with an axe] 1. A person who enjoys exploring the details of programmable systems and how to stretch their capabilities, as opposed to most users, who prefer to learn only the minimum necessary. 2. One who programs enthusiastically (even obsessively) or who enjoys programming rather than just theorizing about programming. 3. A person capable of appreciating hack value. 4. A person who is good at programming quickly. 5. An expert at a particular program, or one who frequently does work using it or on it; as in `a Unix hacker'. (Definitions 1 through 5 are correlated, and people who fit them congregate.) 6. An expert or enthusiast of any kind. One might be an astronomy hacker, for example. 7. One who enjoys the intellectual challenge of creatively overcoming or circumventing limitations. 8. [deprecated] A malicious meddler who tries to discover sensitive information by poking around. Hence `password hacker', `network hacker'. The correct term for this sense is cracker.

The term `hacker' also tends to connote membership in the global community defined by the net (see the network and Internet address). For discussion of some of the basics of this culture, see the How To Become A Hacker FAQ. It also implies that the person described is seen to subscribe to some version of the hacker ethic (see hacker ethic).

It is better to be described as a hacker by others than to describe oneself that way. Hackers consider themselves something of an elite (a meritocracy based on ability), though one to which new members are gladly welcome. There is thus a certain ego satisfaction to be had in identifying yourself as a hacker (but if you claim to be one and are not, you'll quickly be labeled bogus). See also geek, wannabee.

This term seems to have been first adopted as a badge in the 1960s by the hacker culture surrounding TMRC and the MIT AI Lab. We have a report that it was used in a sense close to this entry's by teenage radio hams and electronics tinkerers in the mid-1950s.

Re:Hacker question

[Shadow Wrought]

Thank you both for answering my humble query. It all makes a lot more sense now!

Re:Hacker question

[diaphanous]

You may also want to take a look at the letter Richard Stallman (the hacker who created GNU, wrote GNU Emacs, the GNU Compiler Collection, and the GNU Debugger, among other things), wrote to the New York Times protesting their misuse of the term "hacker".

You can find his letter at the bottom of this page in The Jargon File.

--Phillip

Preempt and XFS???

[Thomas A. Anderson]

Last time I tried using preempt with the XFS filesystem - dmesg had a ton of prepemt errors - any idea if this is fixed (or is it an xfs issue)?

Thanks!

Greg