In part 1 of this two-part series, ExtremeTech examines the performance of Windows XP Pro x64 and 32-bit Windows on a dual-core CPU. This part features the AMD Athlon 64 model on both operating systems. The next part will feature Intel's best dual-core offering.
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Member since:x86_64 is faster due to the extra registers available, so running 64-bit gains speed as things are compiled for that it instead of for x86. If the architecture is no different, just switched from 32 to 64 then yes 64 will be slower, this is the reason most userspace apps are 32 bit under solaris etc.
Member since:2005-07-06
In theory, yes.
But
A. Both MSVC and the GCC's (The rest of the world) level of optimization in 64bit is far from being equal to their 32bit brethren.
B. Driver optimization in 64bit leaves much to be desired. (Especially when it comes to Windows; Linux' code is 32bit/64bit free by design)
C. Memory footprint in 64bit (both code and data) is bigger, lowering the cache hit rate. (Which is /very bad/)
In short, I've yet to see a 64bit OS outperform a 32bit in non server task. (AKA desktop tasks)
Gilboa
Member since:2005-07-06
x86_64 is faster due to the extra registers available, so running 64-bit gains speed as things are compiled for that it instead of for x86.
Not necessarily. Benchmarks suggest that it depends on the application whether the slowdown due to the 64 bits or the speedup due to the extra registers dominates.
Shame AMD didn't make the extra registers available in 32 bit mode as well. With the registers and decoders already there anyway, it wouldn't have cost any significant extra hardware.
Although Microsoft probably would not have bothered with such an extension, gcc and the open source OSs would have been quick to make use of it and gain some extra speed almost for free.
Member since:
2005-07-06
Going back to 32bit? I'm forced to every day in the office and it's a pain...
Huh?
You are kidding, right?
I'm on 64bit since the good-old-days of Alpha/DEC-Unix (currently typing this on a Dual Opteron/64bit FC4) and I fear that you are suffering from an acute case of "way-too-much-marketing-effect".
Unless you have >2GB of memory, and you're running highly optimized memory/CPU intensive applications, your OS, no matter what OS it is, runs slower in 64bit.
Gilboa