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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."
"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?
I have a small program that mmaps a bit of code and then points the program counter at it. Everything runs fun until a OS call happens. I've heard that Mach allows user land programs to install their own OS calls but I haven't seen any example code to do it and I suspect such a feature isn't in OS X. I've hunted through the source and I while I could write my own system call and compile it in, there should be an easier way. Can anyone point me in the correct direction?
"OS virtualization is going to kill off the native OS X software market"
Ahh, and welcome back to another thrilling episode of "doesn't know what the fuck they're on about" theatre!
Honestly. OSV is SLOW compared to native. No one wants slow.
110100 1101000 1101000 1100110 0 1101111 1101000 1100011 1
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?
Not to mention fonts. I can never forgive anyone for using Comic Sans in a presentation.
I also get kinda pissed off because lotsa people write it that way.
Before anyone starts spouting off again about Mac OS X being "slow by design" or somesuch, read this article by an Apple engineer that investigates those claims.
somebody must have mispelled "book commercial" as "presentation".
there's nothing really new in that presentation, most of slashdotters know this stuff already, the only thing that we didn't know as of yet is that you can mispell "book commercial" in such an interesting way.
you can "troll" or "flamebait" my post, but this is the way that it is.
I'd tell you the chances of this story being a dupe, but you wouldn't like it.
I looked at the "presentation" and no, it doesn't do a very good job of explaining anything. Maybe combined with an extensive lecture to explain what the hell he's talking about would make it a bit more clear. From what I saw it was basically just enumerating the different components. Then I noticed the second to last slide. It's basically an ad for a book coming out.
Maybe it's just me though. Did anyone else find it extremely enlightening?
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.
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.
As an ex-NeXT developer, the historical speed bumps behind this architecture are directly related to code density. NeXTSEP ver 2.0 was nicely running on 25mHz. NeXTSTEP ver 3.0 suffered performance on 25mHz compared to ver 2.0 because of the additional kernel overhead resultant from code densification.
With every ver. release through 10.4.x MacOS X, mach/BSD layer exhibits funtional improvements with speed increases of the processor CPU and latent performance behaviors from the additional kernal overhead added by code complexity and densification.
Prima Facia evidence to the 4X speed improvement in performance from Apple's new Intel CPU bears witness to the limits of the kernal architecture.
Nope, it's still gibberish.
whether it's why it's slow
Well... why is it slow?
Mach/micro-kernel makes it bad
Debating the pros and cons of Mach is a valid topic, but a phrase like this is so vague that it's meaningless.
it's going closed source
OK, that one's intelligible. But then we come across gems like this:
for instance they show that there are so many process/threads layers in OS X.
A small request for submitters: Take a minute to actually proof-read your summary. I'm not even talking about simple typos, or the correct use of "you're/your" - those look ugly, but most of the time people can still figure out what you meant. Just ask yourself: will these words make sense to a moderately intelligent English speaker who's not on a meth bender?
You're assuming that the only market for software is medium to large enterprise. Autocad (which is made by a well known vendor) is used by tons and tons of architects. Since I've worked in IT support for a few architectural firms, I can tell you that most of them are comprised of small business of under 50 employees. I've used Autocad under Windows, however when I needed to use something to make some plans for a shed for my church, I used Sketch-Up, because there's an OSX native version.
Furthermore, most of the people that I've run across who are excited about virtualization are primarily interested in using it to run the existing Windows apps they own, and plan on replacing those with OSX native versions where available, and comparable OSX native apps where not available. The other major segment (where I fall into this equation)interested in virtualization, is the IT people who use/support multiple platforms.
Boot Camp is for games. Noone I have spoken with that knows about virtualization is seriously intersted in using it for anything other than games.
What?
I'm not understanding something...
This seems like Carly Fiorina Logic. If we stop making HP calculators, people will just buy handheld HP units with similar funtionality. It doesn't matter that the calculator group provides a substantial net profit for the company. If we stop spending all that money on supporting calculators and simply use the computer support people we already have... Think of the savings!!!!
When a group/division in a company that caters to a market makes the company lots of money, leave them alone. They're doing their job, pulling a PHB stunt in wall street business tactics will only hurt your company.