“There sure are good reasons to use the 64-bit mode but it is not everyone who can do it,” Munger writes.
“The first reason would be your use of ramdom-access memory (RAM). If you have more than 4 GB installed in your Mac, this allows your software to access it. The second is speed. 64-bit operations require less steps, therefore less time to execute,” Munger writes. “However, things are never quite simple.”
Read more in the full article here
[Thanks to MacDailyNews Reader “Fred Mertz” for the heads up.]
i have a mac mini server on order. should i run it in 64 mode and how do you do it?
” If you have more than 4 GB installed in your Mac, this allows your software to access it.”
I don’t think that’s correct. As I understand it, Macs can use all of the available memory even in 32 bit mode. The difference is that any single app can’t be given an address space larger than 4GB.
Pfff. If you have more than 4 GB installed on a non-64-bit EFI Mac, it still uses all of it. 64-bit kernel extensions (device drivers) simply receive the benefit of unlimited kernel address space, larger register file, etc, but 32-bit kernel extensions could still use all of the available memory in a system, without 64-bit mode. Individual 32-bit applications receive their own 4 GB virtual memory space, but any memory they allocate is backed by 4 KB pages from the total memory in the system, not just the first 4 GB of physical memory. This goes back to Jaguar 10.3, with full support in Tiger 10.4. Leopard finally got it right. Snow Leopard just lets recompiled 64-bit kexts have a larger kernel space.
@jim,
I’d run it as Apple sells it. When the engineers at Apple think it’s ready to go a software update will turn it on.
Obviously, you should choose 32 bit or less.
Who wants his data more puzzled?
The one situation I recall is where the first Mac Intel machines (32-bit only) couldn’t even access the full 4 GB of installed memory, because bios reserved a large chunk (256 or 512 MB) of address space for PCI IO. Now that was a bad deal. I’ve had either 8 or 16 GB of RAM in every G5 or Mac Pro since Tiger, and always been able to utilize all of it. FYI, In Snow Leopard, I enable 64-bit kernel mode, with no issues, but with no dramatic performance gain.
64bit…65bit…whatever it takes.
Photoshop offers up to a 32bit mode. With a few adjustment layers open and 50 memory states, forget about using anything short of 16GB of RAM.
@MacRick
Awesome “Mr. Mom” reference.
Why NOT using the 64 bit kernel?
I always do (hold down “6” and “4” keys during boot). The sunspider javascript is quite a bit faster, and heavy task switching should be faster (no permanent flushing of the TLB cache), but no drawbacks with 64b.
Well, as long as all drivers work, which is the case for me. But 3rd party drivers may fail to work or to exist… Therefore Apple is playing it safe by not enabling the 64b kernel on default. All 64b apps still have full access to more than 4GB while running under the 32b kernel. So, 99% of users can and should just ignore this non-issue.
Hold down the 6 & 4 keys when you start up – it turns on 64 bit until you restart
@chabig
It’s already built in so you will be waiting forever if you’re waiting for the engineers to turn it on. Just hold down the 6 and the 4 keys as you boot the computer.
SamLowry has it right. You can check it by going to “About this Mac”, and highlighting “Software”. Under 32-bit, the “64-bit Kernel and Extensions” says “No”. Hold down the “6” and “4” at bootup, and it changes to “Yes.”
Here is a link that explains
how to turn it on/ off
http://support.apple.com/kb/HT3773
NE14Tennis beat me on the instructions
If you have a 64 bit processor, your Mac will run 64 bit applications in 64 bit, regardless of what mode you started your Mac in.
The description of this free utility explains the 32-bit/64-bit situation more clearly than anything else I’ve seen.
http://www.ahatfullofsky.comuv.com/English/Programs/SMS/SMS.html
Note: Some of the information is out of date, such as the list of 64-bit capable Macs and VMware Fusion as an example of a 32-bit kernel extension (a 64-bit kernel extension is now available).
I’m not endorsing this utility, just saying that the information provided explains things in a way that is easy to understand.
I’m not going to worry about it. My Mac runs with the default 32-bit kernel. I have a few third-party hardware devices that need extensions (drivers) which are still 32-bit (and may not ever be updated to 64-bit). By the time I replace my iMac with a future Mac that uses the 64-bit kernel by default, I probably won’t be using those old peripherals anymore.
if you have a 3rd party device who’s driver is not available in 64 bit, then booting to 64 bit will effectively disable the device.. 64 bit apps will still run even if you aren’t booted into 64 bits. this is only for kernel extensions.
64 bit Windows runs in 32 bit OS X under VMFusion.
KisMAC with Apple passive filter is used to watch network traffic to catch people stealing your wifi.
Isn’t mediaxyz correct?
I thought i read that elsewhere when I was looking in to this a while ago.
Great half assed information. Thanks MDN!