jsw said:
Because 64-bit applications will be supported using a 32-bit kernel, this 64-bit support will have no impact on most device driver or kernel extension writers. However, there are exceptions, as explained in Device Driver Issues (page 23).
spaceballl said:Nope it's not cuz 64 is twice as much data to move around and its slower... That's not the case. In reality 64 bits isn't like twice as many as 32... Using binary digits, it is only one more digit, and that's how each bit works.
Basically, I don't see a good reason for Apple to not go 64 bits. They could very easily make a 64 bit version and a 32 bit version of the kernel. In the Unix world, 64 bit and 32 bit binaries can coexist without any problem so I don't know why Apple isn't doing the same in the mac world.
http://www.osnews.com/story.php?news_id=9220
its not out yet its still months away would it be possible for this to be done by tigers releasebroken_keyboard said:they will have some limitations to start with, such as no GUI. But I'm sure that will be resolved in one of the 10.4.x releases. It's not an architectural thing, they just haven't ported the GUI library yet.
Keep in mind that the biggest speed boost with 64-bit on the x86 side comes with the additional registers (from 8 to 16). The PowerPC, on the other hand, has 32 registers already, and doesn't really need more. Therefore, the benefits of 64-bitness are reduced to the increased addressing capabilities it gives. A smart 64-bit implementation could "partition" the 64-bit registers in 32-bit mode, which would give 32-bit applications a speedup similar to what happened with x86-64. There's some slowdowns associated with pointers suddenly becoming twice as big, squeezing other data out of the cache (which can be mitigated by increasing the cache size).derFunk said:64 bit still should not make anything "slower"...the reason being that the registers are 64-bit anyway, and when running in 32bit mode, it's STILL spending half its time writing those extra 32 bits...they're just all 0's. If anything, a 64-bit OS should be FASTER than a 32-bit one, if it's well written, because it can take better advantage of those registers and get some extra work done each clock cycle.
Then again, I'm a Mac newbie and an x86 veteran...this is how it works on the dark side...I figured that if there is not a similar purpose in going 64bit on the Mac side, then the G5 would still be a 32-bit CPU.
Anarchy99 said:its not out yet its still months away would it be possible for this to be done by tigers release
derFunk said:64 bit still should not make anything "slower"...the reason being that the registers are 64-bit anyway, and when running in 32bit mode, it's STILL spending half its time writing those extra 32 bits...they're just all 0's. If anything, a 64-bit OS should be FASTER than a 32-bit one, if it's well written, because it can take better advantage of those registers and get some extra work done each clock cycle.
broken_keyboard said:As for the 64-bit programs themselves, they will have some limitations to start with, such as no GUI. But I'm sure that will be resolved in one of the 10.4.x releases. It's not an architectural thing, they just haven't ported the GUI library yet.
broken_keyboard said:That is correct, but as wrldwzrd89 said, don't forget about the cache. If you use 64-bit pointers when you don't really need to, all you do is fill up your cache faster and get fewer hits, thus slowing your program down.
The way CPU pipelines are designed, you can't split the registers up like that to run two separate sets of 32 bit code.wrldwzrd89 said:A smart 64-bit implementation could "partition" the 64-bit registers in 32-bit mode, which would give 32-bit applications a speedup similar to what happened with x86-64.
That clears that up then. I was just taking a guess; I didn't know that it wasn't possible.spaceballl said:The way CPU pipelines are designed, you can't split the registers up like that to run two separate sets of 32 bit code.
x86-64 didn't give 32 bit apps a speedup because of anything to do w/ the 64 bit part of them. The 64 bit part of them, like G5s, is basically sitting idle. Those Athlon 64s are so damn fast because of their great architecture and on-die memory controller
spaceballl said:The way CPU pipelines are designed, you can't split the registers up like that to run two separate sets of 32 bit code.
x86-64 didn't give 32 bit apps a speedup because of anything to do w/ the 64 bit part of them. The 64 bit part of them, like G5s, is basically sitting idle. Those Athlon 64s are so damn fast because of their great architecture and on-die memory controller
spaceballl said:We should just make CPUs that CAN do that! Well, ****... I guess that's what dual core does haha
You'd be surprised what a simple MSN search will turn up as the first two results for "arstechnica ppc970".derFunk said:Right. There's a great writeup about the K8 architecture here
Can anybody point me to something similar for the G5? I thought that Ars Technica had a big PPC 970 writeup but I'll be darned if I can find it since their site redesign.
Yup yup i meant on the conceptupal levelRincewind42 said:Not quite, but the idea is the same