Constant I/O Access Time(repost)

The attached program was written and tested on Pocket PC Dell Axim X50 using processor Intel PXA270 on Windows Mobile 5 (Windows Mobile 2003 should be fine) using Visual Studio 2005 (eVC++ 4 should be fine). The program first allocates a small memory region. Then it accesses the memory region several times and measures the elapsed clock ticks. The process is repeated for 20 times and the measured time values are put into an array which is written to a file. **Problem:** If you compile and run the original program, you will find the time values quickly converge to a CONSTANT number. However, if you uncomment the code “| PAGE_NOCACHE?? on line 16, you will find the time values diverge greatly. It is because now every time the processor accesses the memory region, it has to access the external memory through the system bus instead of its internal cache. I tried locking the system bus exclusively for the core (line 18) but it was not effective. **Goal:** I need help to make the access time to the non-cacheable memory region CONSTANT, just like when it is cacheable, on the XScale platform. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform Platform: Pocket PC - Processor Intel PXA 270 OS: Windows Mobile 5