Quote:
Originally Posted by Loren
Quote:
Originally Posted by Deathblob
Quote:
Originally Posted by Loren
64bit doesn't add one bit of speed unless you're doing 64bit arithmetic. In general it will actually cost you a bit of speed as 64 bit code is bigger than 32 bit code.
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Yes! That's so true, if you are reading your 64-bit words over an 8-bit bus. |
The memory bus is at least 64 bits, that's not a problem.
The problem is 64 bit code is simply bigger than 32 bit code--fewer lines of code fit into the on-chip caches, you end up with more read cycles to memory. |
Well, I thought those reads should be twice as fast, so I didn't believe you, and went googling.
http://www.osnews.com/story/5768/Are...naries_/page1/
It's a bit old, and Sparc of all things. But looks like you are right.
64bit had ~+20% bigger binaries, ~-10% slower execution.