cache program from dave patterson at UC Berkeley.

util/cachetest/cachetest.c

@@ -0,0 +1,68 @@
+/*  COPYING:
+ *  Dave Patterson at UCB modified this code from a program by Andrea 
+ *  Dusseau of U.C. Berkeley,which was based on a description in 
+ *  Saavedra-Barrera [1992]:
+ *    Saavedra-Barrera, R. H. [1992]. CPU Performance Evaluation and 
+ *    Execution Time Prediction Using Narrow Spectrum Benchmarking, 
+ *    Ph.D. Dissertation, University of Calif., Berkeley (May).
+ *  Patterson has given permission to use and modify this code as long
+ *  as these people and the U. of Cal., Berkeley get proper credit.
+ */
+
+#include <stdio.h>
+#include <sys/times.h>
+#include <sys/types.h>
+#include <time.h>
+#define CACHE_MIN (1024) /* smallest cache */
+#define CACHE_MAX (256*1024) /* largest cache */
+#define SAMPLE 10 /* to get a larger time sample */
+#ifndef CLK_TCK
+#define CLK_TCK 60 /* number clock ticks per second */
+#endif
+int x[CACHE_MAX]; /* array going to stride through */
+ 
+double get_seconds() { /* routine to read time */
+    struct tms rusage;
+    times(&rusage); /* UNIX utility: time in clock ticks */
+    return (double) (rusage.tms_utime)/CLK_TCK;
+}
+
+int main() {
+    int register i, index, stride, limit, temp;
+    int steps, tsteps, csize;
+    double sec0, sec; /* timing variables */
+ 
+    for (csize=CACHE_MIN; csize <= CACHE_MAX; csize=csize*2) 
+        for (stride=1; stride <= 128; stride=stride*2) {
+            sec = 0; /* initialize timer */
+            limit = csize-stride+1; /* cache size this loop */
+     
+            steps = 0;
+            do { /* repeat until collect 1 second */
+                sec0 = get_seconds(); /* start timer */
+                for (i=SAMPLE*stride;i!=0;i=i-1) /* larger sample */
+                    for (index=0; index < limit; index=index+stride) 
+                        x[index] = x[index] + 1; /* cache access */
+                steps = steps + 1; /* count while loop iterations */
+                sec = sec + (get_seconds() - sec0);/* end timer */
+
+            } while (sec < 1.0); /* until collect 1 second */
+     
+            /* Repeat empty loop to loop subtract overhead */
+            tsteps = 0; /* used to match no. while iterations */
+            do { /* repeat until same no. iterations as above */
+                sec0 = get_seconds(); /* start timer */
+                for (i=SAMPLE*stride;i!=0;i=i-1) /* larger sample */
+                    for (index=0; index < limit; index=index+stride) 
+                        temp = temp + index; /* dummy code */
+                tsteps = tsteps + 1; /* count while iterations */
+                sec = sec - (get_seconds() - sec0);/* - overhead */
+            } while (tsteps<steps); /* until = no. iterations */
+     
+            printf("Size (bytes):%7d, Stride (bytes):%4d, read+write:%4.0f
+ns\n",
+               csize*sizeof(int), stride*sizeof(int),
+               (double) sec*1e9/(steps*SAMPLE*stride*((limit-1)/stride+1)));
+        }; /* end of both outer for loops */
+}
+