64 bit 1 CPU vs 32 bit 2 CPU

[FreshPrinceOfBellAir]

If mghz and cache are the same what would be faster: a 64 bit single thread program on 1 CPU vs 32 bit multi thread program on 2 CPUs?
Just wondering

 

[SEALTeamSix]

If mghz and cache are the same what would be faster: a 64 bit single thread program on 1 CPU vs 32 bit multi thread program on 2 CPUs?
Just wondering

That would really depend on if the CPU's were 32-bit or 64-bit... a 32-bit CPU might have a wee bit of trouble with a 64-bit app...

Kidding aside, some of it depends on the amount of memory available... a big advantage of a 64-bit app is the ability to address large amounts of RAM.

-SEAL

 

[robberbaron]

Depends on if its x86-64 or IA64 or some 64bit RISC.

 

[FreshPrinceOfBellAir]

ok, lets say each CPU was set up for best performance and the software was identical except for the 32 & 64 bit

 

[robberbaron]

What kind of 64 and 32 bit? There are lots of architectures, and thus the result would vary.

edit; I'll just assume a desktop platform, so x86 vs x86-64.

As long as 4gigs of ram is enough, the dual cpu x86 will always beat the x86-64 one.

second edit: this is assuming the multitheaded program is coded efficiently enough to give the 90% or so boost we see in some multithreaded apps.

 

[Josh_B]

It really depends on whether or not the code required the 64-bit-ness or not. If the code is all capable of being run on a 32-bit machine, it is unlikely it would have any increase on a 64-bit CPU. If the code uses a lot of longs or doubles, it will be much faster (generally) on a 64-bit CPU.

Your question is too ambiguous. Also, don't forget that AMD64 also doubles the number of GP registers, and would therefore get a boost just from that.