Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
64bit Apps on Leopard
- Thread starter pacmania1982
- Start date
- Sort by reaction score
Leopard and even Tiger have been able to run 64bit apps. The buzz about Snow Leopard is that it will be fully 64bit instead of mixing 64bit and 32bit code in the OS itself.
Aside from a larger addressable virtual and physical address space, x86-64 also brings the to table:
64 bit wide registers with support for 64 bit integer operations.
16 general purpose registers, as opposed to x86's eight. Function calls can pass more parameters via GP registers as opposed to having to pull them from L1 cache.
The ability to reference data relative to the Instruction Pointer, which can improve the performance of shared libs and dynamically loaded code.
An XD bit, which can defeat certain types of buffer overflow exploits.
I suppose, depending on your code, if you refactor and/or aggressively optimize for x86-64, you might be able to get as much as a 10 to 15 percent performance boost. By no means is it a sure thing, but there is more to moving to 64 bits than address space.
64 bit wide registers with support for 64 bit integer operations.
16 general purpose registers, as opposed to x86's eight. Function calls can pass more parameters via GP registers as opposed to having to pull them from L1 cache.
The ability to reference data relative to the Instruction Pointer, which can improve the performance of shared libs and dynamically loaded code.
An XD bit, which can defeat certain types of buffer overflow exploits.
I suppose, depending on your code, if you refactor and/or aggressively optimize for x86-64, you might be able to get as much as a 10 to 15 percent performance boost. By no means is it a sure thing, but there is more to moving to 64 bits than address space.
No it didn't. 64 bit processes were new in Tiger, 64 bit GUI applications are new in Leopard.
That is true on PowerPC, but Intel/x86 architecture is crap with only 8 addressable registers. AMD64 expands the number of registers to 16.
It really is amazing that Rosetta was able to get PPC code (which has 32 registers) to work so well on the puny 8 register Intel chips.
Isn't the XD bit the same as the AMD NX-bit, which has been around since at least 2003?
Even on Leopard the kernel is limited to 4 gigs of address space. I suppose it had the minimum changes necessary to map that address space anywhere in a larger physical memory.
Actually, if you read what I put, I wasn't obsessed with the difference between 32bit and 64bit. I was simply asking if this was normal as I hadn't seen it before
Chill out!
pac