Putting It All Together: Highly Parallel Memory Systems Concept illustrated by this case study ¦ Cross-Cutting Issues: The Design of Memory Hierarchies The program in Figure 2.32 can be used to...

Putting It All Together: Highly Parallel Memory Systems Concept illustrated by this case study ¦ Cross-Cutting Issues: The Design of Memory Hierarchies The program in Figure 2.32 can be used to evaluate the behavior of a memory system. The key is having accurate timing and then having the program stride through memory to invoke different levels of the hierarchy. Figure 2.32 shows the code in C. The first part is a procedure that uses a standard utility to get an accurate measure of the user CPU time; this procedure may have to be changed to work on some systems. The second part is a nested loop to read and write memory at different strides and cache sizes. To get accurate cache timing, this code is repeated many times. The third part times the nested loop overhead only so that it can be subtracted from overall measured times to see how long the accesses were. The results are output in .csv file format to facilitate importing into spreadsheets. You may need to change CACHE_MAX depending on the question you are answering and the size of memory on the system you are measuring. Running the program in single-user mode or at least without other active applications will give more consistent results. The code in Figure 2.32 was derived from a program written by Andrea Dusseau at the University of California-Berkeley and was based on a detailed description found in Saavedra-Barrera (1992). It has been modified to fix a number of issues with more modern machines and to run under Microsoft #include "stdafx.h" #include #include #define ARRAY_MIN (1024) /* 1/4 smallest cache */ #define ARRAY_MAX (4096*4096) /* 1/4 largest cache */ int x[ARRAY_MAX]; /* array going to stride through */ double get_seconds() { /* routine to read time in seconds */ __time64_t ltime; _time64(