Understanding OS X Kernel Internals

jglidell writes "The OS X kernel has been in the news alot this past year, whether it's why its slow, Mach/micro-kernel makes it bad, it's going closed source and what not. Amit Singh has put up a new presentation on the innards of OS X. It does a pretty good job of summing up the OS X kernel architecture, and has some pretty detailed diagrams... for instance they show that there are so many process/threads layers in OS X. So if you are in the mood for doing some OS studying then head over."

Comments

Spelling

[atkulp]

Grrr... "alot" isn't a word! It's "a lot."

The spelling police are on their way!

Re:Spelling

[dhasenan]

Not to mention fonts. I can never forgive anyone for using Comic Sans in a presentation.

huh?

[Aussie]

whether it's why its slow

What the hell does that mean ? Editors drunk ?

Needs more editor.

[dajobi]

"alot"
"whether it's why its slow"
"they show that there are so many process/threads layers in OS X."

Do the editors even look at submissions any more? Or to put it another way, is our children learning yet?

Re:Needs more editor.

[OECD]

Do the editors even look at submissions any more?

I'm afraid they do. I think the problem is that they're not as skilled in writing english as they are in writing PERL. (That's not a slam, by the way. I suck at PERL.)

And before anyone goes on an "Off Topic" jag, it really does make a difference if the readers can understand what's being written. I stumbled over the "that there are so many" sentence a couple times trying to make sense of it. There are so many process threads layers in OS X that what? It slows it down? It's hard to program? Or is there simply a gee-whizz lot?

Yeah, I know, I'm off to R the FA. I just wish I had a better idea of what's in there.

Terrible summary.

[IANAAC]

I could barely get through the summary.

If English is a second language for the submitter, fine. But good grief, do you suppose one of the PAID editors could have done just a bit of work to make the summary more readable?

Re:The average person

[specific]

This isn't news for the average person. This is isn't always news either. What's the problem?

Re:A flash presentation

[DerCed]

I forgot: I HATE FLASH!!!!

Underpowered Little Machine

[Beefslaya]

As the purchaser of a brand new Core Duo Mini, (my first Mac, I feel "as happy as a little Gurlll!") I noticed that my system out of the box with 512 of RAM was dog slow when you start loading iPhoto, or any more then 2 apps.

Initial startup yielded a smoking fast web browser, and other single line items.

I purchased the 2GB Ram upgrade (not from Apple at 600 USD, 280USD from Crucial) and I noticed such a difference, that I couldn't understand WHY they would even consider shipping that little silver wonder with less then 1GB of RAM.

It's not the kernel, it's the apps... They just don't give enough power to the off the shelf machines to support the great apps that come with it.

Vive le Mac... Thanks for putting excitement back into computing for me.

Re:Underpowered Little Machine

[Crizp]

Not to be a total Apple fanboy but all mainstream computer suppliers sell PC's with half the amount of RAM that's usually needed. When Windows ran fine on 128 MB, you got 64. Now you usually get 512 MB, but XP SP2 is slow with less than a gig. Especially if you're playing games, but also using regular apps.

Re:The average person

[LWATCDR]

So go read a less technical website than Slashdot.
This story was boring because the presentation was dumb. It had a little useful information but not much. The subject is interesting.
OS/X security? How to lock it down? There are many sites on the web. Look for just about any good site about UNIX security and start from that. OS/X uses the UNIX security model.

Closed?

[ShadowBottle]

Riiiight. Just because some idiot alarmists say that the kernel has gone closed when it simply just hasn't been released yet, the media and clueless bloggers start crying that it's gone closed source.
"Well... it hasn't. It's still open. IT JUST HASN'T BEEN RELEASED YET.
OSNews is reporting that Ernest Prabhakar, Apple's Open Source and Open Standards product manager, has stated in the Fed-Talk mailing that Apple has not actually closed Mac OS X's Darwin kernel for the Intel version of the OS; they simply haven't released it yet. Speculation about Apple closing the kernel arose from the fact that other non-kernel Darwin sources actually have been released, and the previous PowerPC-based kernel is still available as open source as well.Ernest wanted to make sure that tech media didn't confuse 'speculation' with 'fact'. A good lesson we all could benefit from...."

God damn alarmist idiots.

Re:"OS X is slow" claims investigated

[jcr]

It shows how the author completely misses the criticism that he is trying to address and fails miserably in his arguments.

It does nothing of the kind. Read the whole article, and ALL of the comments, sparky, not just the ones that support your prejudice.

Peter's point is that the "benchmark" in question boils down to how quickly OSX will malloc and free 35KB blocks. It happens to cross the mmap() threshold for kernel versus heap allocations.

It also shows how Apple fanboys applaud the author's explaination, even though they haven't a clue about the subject matter - and even admit it in their posts.

If you had actually refuted anything that Peter had said in his article, you might have a leg to stand on, but since you didn't, and since you toss off an epithet like "fanboy" instead of doing so, I conclude that you are the clueless one.

No wonder you're an AC.

-jcr