On 10/22/05, Kenneth Porter <shiva@xxxxxxxxxxxxxxx> wrote: > --On Saturday, October 22, 2005 1:15 AM -0500 Jonathan Berry > <berryja@xxxxxxxxx> wrote: > > > "64 bit is not going to speed up Doom 3. In fact there may actually be > > a minor slowdown since the pointer references are all in 32 bit, which > > will mean a hit to memory bandwidth which is the real gating problem." > > > > What does "pointer references are all in 32-bit" mean? You can > > address more virtual memory in 64-bit, which usually means that memory > > intensive programs do better. > > Pointers will be 64-bit, which means that instructions that need to load > pointers will touch more memory. Indirection gets more expensive. Without > the greater number of registers that came with AMD64, that might have > inflicted a noticeable performance penalty on his engine. Gamers tend to > obsess over small improvements that programmers consider negligible, so > that would have marketing consequences. Perhaps this is what he meant. Though, let's not forget a DDR memory interface is 64- or 128-bits wide. I don't think it will take any longer to get a 64-bit pointer than a 32-bit one. Right? You get at least 64-bits per (FSB) cycle. I still go back to it was an old quote and maybe doesn't apply anymore. I cannot see any slight memory overhead outweighing the other benefits of x86_64. Jonathan
