Other than the extra memory address space is there any advantages to using a 64bit OS for folding? The reazon i am aaking is i am about to build two crunchers and i have two copies of XP that i can recycle.
Thanks
Thanks
64bit os question
- Thread starter Desslok
- Start date
VirtualLarry
No Lifer
- Aug 25, 2001
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64-bit mode offers more GP registers to programs, so they can be more efficient. This is in addition to the extra memory supported by 64-bit.
Pros and cons
A common misconception is that 64-bit architectures are no better than 32-bit architectures unless the computer has more than 4 GB of random access memory.[21] This is not entirely true:
Some operating systems and certain hardware configurations limit the physical memory space to 3 GB on IA-32 systems, due to much of the 3–4 GB region being reserved for hardware addressing; see 3 GB barrier; 64-bit architectures can address far more than 4 GB. However, IA-32 processors from the Pentium II onwards allow for a 36-bit physical memory address space, using Physical Address Extension (PAE), which gives a 64 GB physical address range, of which up to 62 GB may be used by main memory; operating systems that support PAE may not be limited to 4GB of physical memory, even on IA-32 processors. However, drivers and other kernel mode software, particularly older versions, may not be compatible with PAE.
Some operating systems reserve portions of process address space for OS use, effectively reducing the total address space available for mapping memory for user programs. For instance, 32-bit Windows reserves 1 or 2 GB (depending on the settings) of the total address space for the kernel, which leaves only 3 or 2 GB (respectively) of the address space available for user mode. This limit is very much higher on 64-bit operating systems.
Memory-mapped files are becoming more difficult to implement in 32-bit architectures as files of over 4 GB file become more common; such large files cannot be memory-mapped easily to 32-bit architectures—only part of the file can be mapped into the address space at a time, and to access such a file by memory mapping, the parts mapped must be swapped into and out of the address space as needed. This is a problem, as memory mapping, if properly implemented by the OS, is one of the most efficient disk-to-memory methods.
Some 64-bit programs, such as encoders, decoders and encryption software, can benefit greatly from 64-bit registers, while the performance of other programs, such as 3D graphics-oriented ones, remains unaffected when switching from a 32-bit to a 64-bit environment. It is unusual for a 64-bit program to perform worse than its 32-bit equivalent; this usually only happens due to a bug.[22]
Some 64-bit architectures, such as x86-64, support more general-purpose registers than their 32-bit counterparts (although this is not due specifically to the word length). This leads to a significant speed increase for tight loops since the processor does not have to fetch data from the cache or main memory if the data can fit in the available registers.
Example in C:
If a processor only has the ability to keep two or three values or variables in registers it would need to move some values between memory and registers to be able to process variables d and e as well; this is a process that takes many CPU cycles. A processor that is capable of holding all values and variables in registers can loop through them without needing to move data between registers and memory for each iteration. This behavior can easily be compared with virtual memory, although any effects are contingent upon the compiler.
The main disadvantage of 64-bit architectures is that, relative to 32-bit architectures, the same data occupies more space in memory (due to longer pointers and possibly other types, and alignment padding). This increases the memory requirements of a given process and can have implications for efficient processor cache utilization. Maintaining a partial 32-bit model is one way to handle this, and is in general reasonably effective. For example, the z/OS operating system takes this approach, requiring program code to reside in 31-bit address spaces (the high order bit is not used in address calculation on the underlying hardware platform) while data objects can optionally reside in 64-bit regions.
As of June 2011, most proprietary x86 software is compiled into 32-bit code, with less being also compiled into 64-bit code (although the trend is rapidly equalizing[citation needed]), so most of that software does not take advantage of the larger 64-bit address space or wider 64-bit registers and data paths on x64 processors, or the additional general-purpose registers. However, users of most RISC platforms, and users of free or open source operating systems (where the source code is available for recompiling with a 64-bit compiler) have been able to use exclusive 64-bit computing environments for years. Not all such applications require a large address space or manipulate 64-bit data items, so these applications do not benefit from these features. The main advantage of 64-bit versions of such applications is the ability to access more registers in the x86-64 architecture.
http://en.wikipedia.org/wiki/64-bit#Pros_and_cons
A common misconception is that 64-bit architectures are no better than 32-bit architectures unless the computer has more than 4 GB of random access memory.[21] This is not entirely true:
Some operating systems and certain hardware configurations limit the physical memory space to 3 GB on IA-32 systems, due to much of the 3–4 GB region being reserved for hardware addressing; see 3 GB barrier; 64-bit architectures can address far more than 4 GB. However, IA-32 processors from the Pentium II onwards allow for a 36-bit physical memory address space, using Physical Address Extension (PAE), which gives a 64 GB physical address range, of which up to 62 GB may be used by main memory; operating systems that support PAE may not be limited to 4GB of physical memory, even on IA-32 processors. However, drivers and other kernel mode software, particularly older versions, may not be compatible with PAE.
Some operating systems reserve portions of process address space for OS use, effectively reducing the total address space available for mapping memory for user programs. For instance, 32-bit Windows reserves 1 or 2 GB (depending on the settings) of the total address space for the kernel, which leaves only 3 or 2 GB (respectively) of the address space available for user mode. This limit is very much higher on 64-bit operating systems.
Memory-mapped files are becoming more difficult to implement in 32-bit architectures as files of over 4 GB file become more common; such large files cannot be memory-mapped easily to 32-bit architectures—only part of the file can be mapped into the address space at a time, and to access such a file by memory mapping, the parts mapped must be swapped into and out of the address space as needed. This is a problem, as memory mapping, if properly implemented by the OS, is one of the most efficient disk-to-memory methods.
Some 64-bit programs, such as encoders, decoders and encryption software, can benefit greatly from 64-bit registers, while the performance of other programs, such as 3D graphics-oriented ones, remains unaffected when switching from a 32-bit to a 64-bit environment. It is unusual for a 64-bit program to perform worse than its 32-bit equivalent; this usually only happens due to a bug.[22]
Some 64-bit architectures, such as x86-64, support more general-purpose registers than their 32-bit counterparts (although this is not due specifically to the word length). This leads to a significant speed increase for tight loops since the processor does not have to fetch data from the cache or main memory if the data can fit in the available registers.
Example in C:
Code:
int a, b, c, d, e;
for (a=0; a<100; a++)
{
b = a;
c = b;
d = c;
e = d;
}The main disadvantage of 64-bit architectures is that, relative to 32-bit architectures, the same data occupies more space in memory (due to longer pointers and possibly other types, and alignment padding). This increases the memory requirements of a given process and can have implications for efficient processor cache utilization. Maintaining a partial 32-bit model is one way to handle this, and is in general reasonably effective. For example, the z/OS operating system takes this approach, requiring program code to reside in 31-bit address spaces (the high order bit is not used in address calculation on the underlying hardware platform) while data objects can optionally reside in 64-bit regions.
As of June 2011, most proprietary x86 software is compiled into 32-bit code, with less being also compiled into 64-bit code (although the trend is rapidly equalizing[citation needed]), so most of that software does not take advantage of the larger 64-bit address space or wider 64-bit registers and data paths on x64 processors, or the additional general-purpose registers. However, users of most RISC platforms, and users of free or open source operating systems (where the source code is available for recompiling with a 64-bit compiler) have been able to use exclusive 64-bit computing environments for years. Not all such applications require a large address space or manipulate 64-bit data items, so these applications do not benefit from these features. The main advantage of 64-bit versions of such applications is the ability to access more registers in the x86-64 architecture.
http://en.wikipedia.org/wiki/64-bit#Pros_and_cons
blckgrffn
Diamond Member
I would vote 64-bit as well, especially with the growing memory requirements of some of the programs - and the ability to run cruncher VMs for specialized projects is easier with 8GB of ram than ~3GB.
Does anyone know if one of the tech sites has done a 32 vs 64 bit test for F@H? I keep coming up with zippo searching it.
Anyone have a couple copies of Vista in a 64bit flavor they want to offload cheaply???
Anyone have a couple copies of Vista in a 64bit flavor they want to offload cheaply???
petrusbroder
Elite Member
- Nov 28, 2004
- 13,343
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Does anybody have a 64-bit version of WinXP Pro for give-away? It would find a good home in Sweden ...
petrusbroder
Elite Member
- Nov 28, 2004
- 13,343
- 1,138
- 126
That's alright. As long as the Operating System can execute 32-bit code, it won't make a difference, if the OS is 64-bit. The OS will still allocate enough memory to run the 32-bit code efficiently, while maintaining other executables, runtimes, etc with the remaining memory.
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