| I don't need to cast aspersions. Apple's claims about performance primarily applied to OS X when run on a specific version of the PowerPC processor: http://www.ece.uprm.edu/~nayda/Courses/Inel4215F03/power64.p... (See pages 304-306.) But, there was a cost to that dependent on architecture. If you read the document I linked above, you'll see that there is a cost to this 64-bit translation -- the performance is not completely equivalent to a 64-bit application running on a 64-bit kernel where there is no need for translation. And yes, there were performance tradeoffs. A 64-bit application running on a 32-bit OS still had all of the 32-bit limitations enforced (limit on maximum process size, number of file descriptors, etc.). And once Apple made the transition to x86 from PowerPC they lost the built-in hardware advantage. x86 can also run 64-bit applications on a 32-bit kernel, but the cost of doing that hardware switch is not as cheap as it was on PowerPC. I also think it's very telling that Solaris, Linux, and Windows opted to never do this as well. And now that OS X no longer offers a 32-bit kernel, this all seems moot anyway. |