Official Mac OS X 10.6 Snow Leopard Thread & FAQ

lighthart2000 said:
What I want to know ... is why Apple has hobbled my flagship product (Mac Pro, Quad Xeon, 8 gig memory) with a 32bit EFI. Imagine my surprise when SL came out and I don't have 64bit kernel support!

I use almost all the apps listed in the following performance review, and hence am missing out on some serious performance increases!
Click to expand...

Even though your kernel runs in 32-bit mode, applications (if so written) will run in all of 64-bit glory.

That means that those applications will run exactly the same whether you boot into a 32-bit kernel or a 64-bit kernel.

You are not missing out on any kind of real or perceived "performance boost" by running a 32-bit kernel. Any 64-bit applications will run in 64-bit space, with all the same 64-bit performance increases, the same as they would on a computer that boots into a 64-bit kernel.

Just FYI, the only Apple computer that boots into a 64-bit kernel is the XServe.

To sum it up, you're not missing out on anything. You can address all your RAM in your computer, and OS X doesn't run any faster in 64-bit mode than it does in 32-bit mode.

The amount of "bits" of a kernel has extremely little to do with "speed."
 
ElDiabloConCaca said:
Even though your kernel runs in 32-bit mode, applications (if so written) will run in all of 64-bit glory.

That means that those applications will run exactly the same whether you boot into a 32-bit kernel or a 64-bit kernel.

You are not missing out on any kind of real or perceived "performance boost" by running a 32-bit kernel. Any 64-bit applications will run in 64-bit space, with all the same 64-bit performance increases, the same as they would on a computer that boots into a 64-bit kernel.

Just FYI, the only Apple computer that boots into a 64-bit kernel is the XServe.

To sum it up, you're not missing out on anything. You can address all your RAM in your computer, and OS X doesn't run any faster in 64-bit mode than it does in 32-bit mode.

The amount of "bits" of a kernel has extremely little to do with "speed."
Click to expand...

El,
Can you explain why the performance review shows an increase in performance between 32bit SL and 64Bit SL in the apps that I use almost every day? (Real world stuff) I'm sure bigger and more files would broaden the gap:

Graph-HeliconFocus411.gif


And holding down the 6&4 when booting will give you the 64bit kernel.. on those platforms that support it -- which the later model mac Pros do!

Graph-Lightroom-import128.gif
 
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Your linked graph shows a ~3% performance increase.

Which tests show a 30% increase in performance?

And what is "performance?" Speed? Memory footprint? A single Photoshop filter?

And are these tests testing Mac OS X booted into a 32-bit kernel vs. a 64-bit kernel, or Lightroom booted into 32-bit mode vs. 64-bit mode (because it's possible to run a 64-bit Lightroom in a 32-bit kernel)?
 
ElDiabloConCaca said:
Your linked graph shows a ~3% performance increase.

Which tests show a 30% increase in performance?

And what is "performance?" Speed? Memory footprint? A single Photoshop filter?

And are these tests testing Mac OS X booted into a 32-bit kernel vs. a 64-bit kernel, or Lightroom booted into 32-bit mode vs. 64-bit mode (because it's possible to run a 64-bit Lightroom in a 32-bit kernel)?
Click to expand...

El,
I have to admit the 30% increase is between Leopard (32bit kernel and app) and the 64bit kernel and app in SL. As you pointed out there is only about a 3-5% between the 32bit and 64bit kernels. And the graph is showing both 32bit and 64bit apps(green and blue respectively) and SL 32 & 64bit. Notice this is only loading 128 files (a very small catalog in LR), most of my imports would be on the order of 2-3000. My assumption is that the gap would widen as this would "stress" the kernel more. And performance as I would perceive it is all of the above.. how fast I can load images, how fast I can batch change, how long a given filter takes to apply... my guess is the kernel would only come into play in the load (as I'm given to understand the kernel will get involved in any i/o intensive operation disk -> graphics card/memory -> back to disk).

Thanks for your input! I guess I am still rankled by the "perception" of being hobbled, even if its only 3-5%. Again remember the newer Mac Pros are 64bit kernel capable.. I am really thinking about my early adopter status...
 
One of the reasons that all Apple "consumer" machines (barring the XServe) boot into a 32-bit kernel is that all kernel-level drivers must be of the same architecture and bit-width as the kernel.

OS X is UNIX, and UNIX has a ton of drivers (especially with a microkernel like OS X uses), and if you boot into a 64-bit kernel, then all those drivers must also be 64-bit. For the consumer use of OS X, not all kernel-level drivers (or "kexts") have been ported/recompiled as 64-bit drivers, so in order for Apple to offer the most compatibility, they defaulted to a 32-bit kernel.

I understand the concern, though -- even if it seems artificial. If the computer can do 64-bits, then it should do 64-bits... the only problem is that the drivers for said 64-bit computer may not all be 64-bit.

Still, applications can and will run in 64-bit space if and when they can. Mathematica, Maple, etc., all run in 64-bit glory and get the same 64-bit performance increases whether the kernel is booted in 32-bit or 64-bit mode -- there is absolutely no difference in the behavior and speed of the app itself.
 
Ok, now we are getting to some meat (smile). I have been through the issue on Windows with 32 and 64 bit drivers and applications. One of the reasons this (all) is key is that I believe 64bit is slowly "coming into it's own" and now we are "feeling the pinch" as both platforms struggle with implementation. I have an AMD 64bit that I have both 32 and 64 bit Windows (xp, vista, and windows 7 loaded). 64bit app support is lagging in the windows world, so Apple is "in parity".

I guess what I am saying is in my excitement I bought into the "marketing hype" of SL as a "true" 64bit platform, when in *complete* technical reality we (consumers) are not "there yet". We are "sorta there" with the 64bit apps running in 32bit kernel... and I understand what you are saying relative to the kexts.... another reason it took so long for Windoz 64 to come out in all it's dubious glory was the drivers.

So now with Windows 7 launching in all its 64bit goodness, was Apples response SL? And will that be enough? Time will tell. I look forward to the next OS X release with full 64bit support (and yes.. on my Mac Pro 1,1).
 
Oh I didn't see any response to my last query? Anyone see a significant "snappiness" increase in SL clean install over the upgrade? I did both and the SL clean install on my MBP feels much "snappier" (seems to boot faster, windows open faster, just all around "faster") And sorry.. no "benchmarks" to prove this...
(I did install a 500gig 7200 rpm HD in my MBP but I really don' think that is the reason).
 
I try to downgrade a MacPro to Leopard but when I insert the Leopard disc (10.5.4). The machine won't boot up.

Any idea?

Thanks~
 
jeno said:
I try to downgrade a MacPro to Leopard but when I insert the Leopard disc (10.5.4). The machine won't boot up.
Click to expand...

Are you trying to downgrade your Macintosh to an earlier version of OS X than the version it came with? Generally, you can't do that.
 
Yup, It is a Macpro with 10.6 pre-installed. I can re-image the machine using CCC back to Leopard and now I want to try re-install fresh using the Leopard disc but it won't start up.
 
You can't install a version of OS X on a Mac that is earlier than the version of OS X that shipped with the computer (with some exceptions, see below).

If your computer shipped with 10.5.8, you cannot install 10.5.7, 10.5.6, 10.5.5, etc. on it.

If you computer shipped with 10.6, then 10.6 is the lowest you'll be able to go.

As you've found out using CCC, you can get a version of OS X that is earlier than the version that shipped with the machine onto it, but it requires imaging and cloning. You can't boot from the Leopard DVD and do the same.
 
Hello ElDiabloConCaca,

Thanks for the clarification. I've using CCC to downgrade all this while and haven't encounter any problem. Do you (or anybody else) have any concern regarding this? Obviously the OS is not mean not be run on the machine and obviously it does not have all the updated driver and ROM information. I'm not sure if by setting up a machine up this way will it still take the full advantage and release the full performance of the machine? how stable can this be?

Cheers,
Jeno
 
You shouldn't care. You really shouldn't. Anything but an Xserve will boot into the 32-bit kernel (and extensions) per default, and switching to the 64-bit kernel (and extensions) has no real user benefits, which is the reason that Apple didn't choose it as the default on supported machines. There are lists on the internet about which machines theoretically can boot into the 64-bit kernel, but best simply ignore those. Even with 32-bit kernel and extensions, a 64-bit processor (any intel Mac that's not a Core Solo or Core Duo, i.e. the Xeons and the Core2Duo processors) in Leopard and Snow Leopard can still run 64-bit software in its full glory.
 
...and switching to the 64-bit kernel (and extensions) has no real user benefits, which is the reason that Apple didn't choose it as the default on supported machines.
Click to expand...
This is not the reason that Apple chose to make consumer Macs boot into a 32-bit kernel.

The reason is that a 64-bit kernel requires all kernel extensions to be 64-bit kernel extensions, and a good amount of kernel extensions required for smooth Mac OS X client operation are but 32-bit at the moment. If Apple made OS X boot into the 64-bit kernel by default, then a lot of functionality of OS X would be lost until a lot of kernel extensions could be recompiled as 64-bit kernel extensions.

The XServe, on the other hand, has to support far less kernel extensions on average because it's typically not a consumer machine where a lot of 3rd-party and after-market kernel extensions need to be installed, not to mention that most server-flavor applications are already 64-bit and any kernel extensions they require are 64-bit.

Performance has nothing to do with why Apple made consumer machines boot into a 32-bit kernel by default. A 64-bit kernel will increase performance somewhat, albeit a lot less than what people really think.

It is true that a 32-bit kernel can run 64-bit applications without a problem, and it is true that the majority of people making a fuss about their Macs not booting into a 64-bit kernel don't really even know what benefits that would have for them -- they just think, "Hey, 64-bits is better (faster) than 32-bits, and Apple is artificially crippling my machine!" when in actuality, if given a double-blind test of a 32-bit kernel machine and a 64-bit kernel machine, they wouldn't be able to tell the difference without being explicitly told which is which.
 
I've noticed quite a few questions about people thinking that they might have a virus on OS X.
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anatrud said:
I've noticed quite a few questions about people thinking that they might have a virus on OS X.
Click to expand...

The Mac's market share has about doubled in the last few years. According to Apple, about half of those new users are previous Windows users. That means that there are now millions of Mac users who until fairly recently only knew how to use a Windows PC, and who are basically Mac newbies.

On a Windows computer, if you are having problems, it is natural to assume that the problems may be due to a virus, since viruses are so common on Windows.

Mac users who are former Windows users, when they have a problem with their Mac, often fall back on their Windows experience and jump to the conclusion that they have a virus. This is almost never appropriate.

When you have an odd problem with your Macintosh, you should assume that it is *not* due to a virus. You should first expect it to be due to something fairly innocuous, and easy to fix, like a corrupted preferences file, or an application that isn't compatible with the version of the OS that you are running, or something of that nature.

You might find this troubleshooting guide helpful:
http://www.macosxhints.com/article.php?story=2004011205473937
Note the conspicuous absence of any suggestions to run anti-virus software.
 
It is funny, hunting down Phishing sites last night, I had one try to load a
phage.gif
. It was caught by an anti-virus program . . . but . . . what would have happened?

I would have a file sitting on my desktop doing . . . nothing. It cannot run on a Mac.

I think there is a bit of understandable paranoia
freakingout.gif
born by the fact that PC users around us have thousands of viruses to worry about with the usual horror stories. "Are we missing something."

No. :)

--J.D.
 
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