Detailed Technical Look at Mac OS X 10.6 Snow Leopard

[relimw]

A whole 6GB! Any machine with a hard drive small enough to benefit is too old to run SL.

Eh, my 250GB OS drive only has 6GB left on it (too many programs that INSIST that they MUST install on the boot drive...), I'd love to have an extra 6GB free.

However, since I've got gobs of code and/or programs that won't run under 10.6 yet, I'm going to defer upgrading my main machine until a) I can get upgrades for the programs I don't have the source for, and b) recompile all of our code on the one machine I have that is running 10.6.

 

[relimw]

It took a full day to upgrade. The installer refused, saying my boot disk is unbootable. I spent the afternoon, evening, and overnight and eventually deleted the startup volume, recreated it, restored, all in order to be able to upgrade. The absolute worst Mac upgrade ever, and I mean since System7!

Hmm, it only took me about an hour to not only upgrade the OS, but also find upgrades for most of the programs we use on our Macbook Pro, and I even did a disk verify first.

 

[bankshot]

I don't think I blew my 'theory.' I said I was quite confident a 32-bit OSX app can not use all 4GB of the address space, because the kernel is using some of it. My test tends to support my statement. The only question is where the boundary is drawn.

I wonder if it's a hardware limitation rather than an OS limitation as you seem to be claiming. You said you're running your test on a G5 - I'm not sure if there is such a limitation on those machines. I'd run your test on the G5 we have at work, but it's still on Tiger and I don't know if that also makes a difference. The discussion here is about Leopard and Snow Leopard. Maybe I'll run it anyway just for fun.

However, I do know that the Intel Macs prior to the Santa Rosa chipset cannot use a full 4 GB of physical memory. This is a limitation of the chipset. It's been well known (and widely discussed here at the time) that pre-Santa Rosa Macs with Core2Duo processors can utilize something like 3.3 GB of memory, but not a full 4 GB. That's why my Core2Duo Mac mini has 3 GB of memory instead of 4 - it didn't make sense to pay extra for a just partial GB more.

My execution of your program bears that out. On my Mac mini Core2Duo:

Total allocated is 3688311888

Interestingly, my CoreDuo MacBook (which can't physically have more than 2 GB memory) also comes up with the 3688311888 number. I don't know if that blows my theory out of the water.

What we need is for someone with a post-Santa Rosa chipset Mac to run your program in 32-bit mode and see what happens. That ought to settle it.

Oh, one more data point - I decided to fire up my old G4 and run the test. It gets 3690359888 bytes, or 2048000 more than the Intel machines. Interesting!

 

[avkills]

Don't worry, Apple will find a way.. They've got to keep making your purchase lose value, so you'll buy buy again.
There is no way an OSX can process can use 4GB. The kernel has to use some of the address space. Linux can be compiled to use only 256MB, so I'd figure OS X can't beat that. I actually think the maximum in OSX is the same as Windows default: 2GB. If you can point to documentation that says otherwise, point away.

No you blew this theory away. OS X can clearly use more than 2GB per 32bit process.

-mark

 

[Amdahl]

I wonder if it's a hardware limitation rather than an OS limitation as you seem to be claiming.

Probably not, since it seems to be running until it runs out of virtual address space, completely independent of actual RAM in the system.

However, I do know that the Intel Macs prior to the Santa Rosa chipset cannot use a full 4 GB of physical memory.

That is probably a 32-bit limit as well, but physical address and virtual address are actually quite separate things.

What we need is for someone with a post-Santa Rosa chipset Mac to run your program in 32-bit mode and see what happens. That ought to settle it.

Oh, one more data point - I decided to fire up my old G4 and run the test. It gets 3690359888 bytes, or 2048000 more than the Intel machines. Interesting!

I think it means that something from the kernel is reserving the space for some purpose, and there are small variations in the reserved size based on hardware platform. Other sources have documented that OSX doesn't store as much data in the virtual address space of a program as Windows, and that system calls are slower because of that. (Each syscall requires the CPU to switch to the OS virtual address space, then back to the program address space) What is being stored in the program space?

 

[Amdahl]

No you blew this theory away. OS X can clearly use more than 2GB per 32bit process.

-mark

That is hardly a theory, when in the sentence right above it I said OS X probably can't do any better than Linux, which can allow 3.75GB to the program. 2GB was just my first guess on where the line would be, based on the documentation that showed a maximum malloc allowed of 2GB.

 

[AidenShaw]

The difference is windows 7 is built directly off Vista, making it a service pack.

SL is an actually rewritten OS.

God, sometimes I'm almost ashamed to be a Mac user when such drivel like this gets posted. Really.

I hate to tell you, but Windows 7 is based on Windows Vista, and Snow Leopard is based on Leopard.

Actually, Windows 7 is based on Windows Server 2008, which is based on Windows Vista, which is based on Windows Server 2003, which is based on Windows XP, which is based on Windows 2000, which is based on Windows NT 4, which is based on Windows NT 3.51, which is based on Windows NT 3.5, which is based on Windows NT 3.1. (Windows 3.1, Windows 9x are not in the path.)

 

[CQd44]

Actually, Windows 7 is based on Windows Server 2008, which is based on Windows Vista, which is based on Windows Server 2003, which is based on Windows XP, which is based on Windows 2000, which is based on Windows NT 4, which is based on Windows NT 3.51, which is based on Windows NT 3.5, which is based on Windows NT 3.1. (Windows 3.1, Windows 9x are not in the path.)

I laughed harder than I should have. :[

 

[AidenShaw]

I laughed harder than I should have. :[

Here's the OSX timeline:

Expanded at History of Unix (pdf - NextStep starts at page 6, OSX shows up on page 11)

Credit to http://www.levenez.com/unix/

 

[Wotan31]

And unlike Apple, Microsoft does not switch their targeted hardware platforms every two years while at the same time abandoning the 'older' architectures.

Hhahahhaa now that is humor! I can't even count how many Windows 3.1 programs I have that will NOT run under Windows 95. Or how many Windows 95 programs I have that will NOT run on windows 98. Or how many Windows 98 programs I have that will NOT run on Windows 2000 or XP. And how many Windows 2000/XP programs I have that will NOT run on Vista.

Microsoft has a track record that is laughable at best for maintaining backwards compatibility. It's actually quite disgusting thinking how much $$$ spent on software that only worked on ONE version of Windows.

MS has been married to the x86 architecture since forever, so not too many target hardware platforms. Unless you count Windows for the DEC Alpha that was suddenly abandoned, leaving its customers out to dry.

 

[drsmithy]

That's pretty much the norm for new versions of software (OS X 10.0 aside).

It was the same for OS X 10.0 as well, which could have justifiably been called NeXSTEP 5.0.

 

[AidenShaw]

Microsoft has a track record that is laughable at best for maintaining backwards compatibility.

You're talking about forward compatibility. "Backwards" compatibility would be trying to run a Vista program on NT4.

Unless you count Windows for the DEC Alpha that was suddenly abandoned, leaving its customers out to dry.

Both of them...

It was the same for OS X 10.0 as well, which could have justifiably been called NeXSTEP 5.0.

Look at the OSX timeline a few posts back at #134 - NextStep appears on page six in 1988, OSX shows up on the Next/OpenStep path on page 11....

 

[drsmithy]

MS has been married to the x86 architecture since forever, so not too many target hardware platforms. Unless you count Windows for the DEC Alpha that was suddenly abandoned, leaving its customers out to dry.

Windows NT is currently active maintained on:

• x86
• x86-64
• Itanium
• PPC (the XBox360 OS)

It was previously available on:

• Alpha (NT 3.1 - Windows 2000 RC2)
• MIPS (NT 3.1 - 4.0)

It was also ported to, but not publicly released on:

• SPARC
• PA-RISC
• Intel i860 (the original target platform, from which it was ported to x86, et al)

 

[Data]

Great article and great read even do i'm not a dev, it made me understand much better what 10.6 is all about.

I updated 4 macs so far with the 10.6 disk and none of them have reported any problems what so ever, the install was around 45 minutes a piece.

 

[Amdahl]

You're talking about forward compatibility. "Backwards" compatibility would be trying to run a Vista program on NT4.

I think he meant *wards compatibility... But seriously, the only company that does *ward compatibility better than Microsoft is probably someone like Sun (Solaris), or IBM, HP, etc with their server OS. Wotan31 is trolling you. Afterall, I always hear Mac fans justifying Apple dropping support for older apps by saying they don't want to be like Microsoft.

Both of them...

Don't forget the MIPS and PowerPC version users!

* = back or for, whatever makes sense.

 

[Mr. Wonderful]

Frankly, the people who are saying that Snow Leopard is a full OS release are just as incorrect as the people claiming Snow Leopard to be a service pack.

It's not a free service pack, and it's not a full OS release as seen in the past retailing at $129. It's a $30 upgrade to Leopard that is somewhere in between. It's reflected right in the price. It's an OS upgrade on the level of $30 instead of $129. Or, if you would rather, the upgrade is at 23% (30/130) of what would be considered a full OS upgrade based on value.

 

[AidenShaw]

I think he meant *wards compatibility... But seriously, the only company that does *ward compatibility better than Microsoft is probably someone like Sun (Solaris), or IBM, HP, etc with their server OS.

Yes, an example of *wards compatibility in Windows is that ConcRT - the new Windows API set similar to Grand Central - will be supported on XP, 2003, Vista, 2008 and Windows 7.

 

[Wotan31]

I think he meant *wards compatibility... But seriously, the only company that does *ward compatibility better than Microsoft is probably someone like Sun (Solaris), or IBM, HP, etc with their server OS. Wotan31 is trolling you. Afterall, I always hear Mac fans justifying Apple dropping support for older apps by saying they don't want to be like Microsoft.

Don't forget the MIPS and PowerPC version users!

* = back or for, whatever makes sense.

LMAO! You don't have much unix experience if you think Sun, IBM and HP have *ward compatibility. YOU sir are the troll in this thread spreading your misinformation. Every major application I can think of runs on ONE version of HP-UX and one version only. Same with AIX. Same with Solaris.

Want to run Oracle 9i database on your HP-UX 11.11 server? Fine, but you have to download Oracle for HP-UX 11.11. What's that now? You're going to upgrade to HP-UX 11.31? Ok, well you need to download a completely different Oracle binary package and installer that will run on 11.31. But OOPS! Oracle 9i is not available for HP-UX 11.31! That means you are forced to upgrade to Oracle 10g if you want to use HP-UX 11.31.

So stop your trolling - you have no commercial unix application experience and it's painfully obvious.

 

[AidenShaw]

Every major application I can think of runs on ONE version of HP-UX and one version only. Same with AIX. Same with Solaris.

More than anything else, this explains why Windows has around 75% server market share. (The "Linux kernel version hell" is worse than the "Windows DLL hell" ever was...)

This week I built a Windows2008 server with SQL Server 2000, it runs fine. (The app had some absurd tie to SQL Server 2000, but SQL Server 2000 runs almost anywhere....)

Some folks at Apple didn't understand "the Windows *wards way" when they did Exchange support for 10.6.

Apple only supports the latest service pack of the latest release of Exchange.

... which almost no one is running in production yet.

 

[relimw]

However, since I've got gobs of code and/or programs that won't run under 10.6 yet, I'm going to defer upgrading my main machine until a) I can get upgrades for the programs I don't have the source for, and b) recompile all of our code on the one machine I have that is running 10.6.

Interestingly enough, I did some compile/run tests last night, just changing from gcc-4.2 to llvm-gcc-4.2 gained a speed increase in our most cpu-intensive software of around 7%, clang didn't net any tangible speed increases. Mind you, nothing in the code was changed.

 

[MikePA]

Finally received my SL DVD from Amazon (pre-order). Took about 30 minutes to install on my iMac. No issues. Got 21 gigs back.

 

[sidewinder]

you can use more than 4GB of RAM on x86 Windows, but the application has to be coded for it and there are limitations.

This is true ONLY if you are running a system with Windows Server 2003, Enterprise Edition or later as the OS.

Since the average Windows user is not running a server OS on their desktop, what you wrote is not relevant.

S-

 

[Augure]

I don't care about Snow Leopard

The first time I bought a Mac was because of the stability of course, but also the ergonomy/interface wich are a big gain on productivity and ease-of-use for a non-developper (other business to care, no really interested, otherwise I would be on Ubuntu now)

Till 6 month ago or so, I was happily optimizing my Mac and softwares (Firefox, Itunes, CS4...) to gain more productivity and enjoy my Leopard experience.

But as I was updating my Firefox with addons and labs, my social network, my various softwares, I started to feel more and more the slow pace of optimization for basics functions that I could find or non-natural extended use off soft such as quicksilver.

I had to give up Itunes as well, a software that I've been using for 7 years, and funny thing, I ended up on a version 2 of itunes on an old computer and compared it to the version 10: not much as changed !
No really, basic functions such as subgenre browsing or label/release information field aren't still implemented, no wma reading on mac, and there are almost no plugins...

I hate windows, and recently had to use a XP with parallels, but I used a 7 beta aswell and it's not that bad especially the available media player software.

So refinement is okay, but 2 years after it's announcement ? Just for a refinement....It's like mac is getting more and more casual, maybe in a good way when it comes to casual users, but in the bad way otherwise.

So: NO ! Thinking about 10.7 is not that early.

 

[mr666]

Should Apple be more like Microsoft" and hang onto OS 10.2 support for nine years like XP support going on forever? If a banana doesn't taste like an orange, which one is wrong?

What are a couple of these "customer-hostile corporate policies"? Do you mean they design their products in a way that customers hate them? That must be why their sales, profits, and stock value are soaring. They should let a committee of 15 million make every decision.

No one "abandons" older "architecture". Apple doesn't switch their targeted hardware platforms every two years. They make much more advanced computer models every six months, so why not make the OS as advanced as possible for those new models? They merely stop making new OS software for their own eight year old "computer models". Microsoft doesn't make computers. The computer hardware makers are shamefully guilty of dragging their feet and keeping PS2 and BIOS on their new models when such hardware and startup scheme is ancient. That keeps Microsoft hog-tied when it comes to innovation and dropping ancient technology. They are left with their old reliable method of innovation which is to copy the features of Mac OS and present them to the world as new ideas glossed over with slightly different (widget-gadget) names. MS would love to drop BIOS support, but they can't get the stodgy old PC makers to get in step with the 21st century.