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We need to build an imaging system on 64 bit hardware and Pco Edge camera is connected through their special PCIe card. As this application is a real-time or near real-time imaging system, we would like to know if there is any difference in performance between 32 bit Windows 7 and 64 bit Windows 7 for PCIe communication. As for the camera PCIe card, it has 64 bit driver.

I understand 64 bit OS can handle more memory and little faster than 32 bit one but I searched on web about PCI communication but couldn't find any related material. Any clue or hint would be welcome.

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Tae-Sung Shin
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    As long as you know that the hardware has a 64-bit driver, you should have no reason not to upgrade to 64-bit. However, the advantages in terms of performance will be negligible for doing I/O on the PCIe bus. – allquixotic Oct 24 '12 at 15:37
  • Depending on the application, you might find latency to be the limiter. Throughput etc might not tell the whole story. As an example: for real-time audio (guitar amp simulators, etc) 15ms+ is a noticeable--and often unacceptable--delay. 32bit/64 bit may have little bearing on latency. – horatio Oct 24 '12 at 16:01

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There should be no significant difference.

The only difference would be that on a 64-bit operating system, typically more low memory space is reserved for DMA (or mapped device memory), which might improve performance slightly. Reserving low memory space is free on a 64-bit OS (since accessing memory mapped at addresses over 4GB is no more difficult than addressing memory mapped lower). On a 32-bit OS, low memory space reserved for DMA reduces the amount of RAM the system can address, so it's typically minimized.

This usually only affects devices that can benefit from large hardware mappings, such as video cards. The effect on this particular device may be minimal or zero. (Typical 32-bit systems have about 300MB reserved for DMA or hardware mappings. Typical 64-bit systems have about 800MB reserved.)

David Schwartz
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