/* * Random page access with * a gaussian distribution. * * Allocate a large (zero fill on demand) address * space and fault the pages in a random gaussian * order. */ #include <math.h> float rnd(), gauss(); char *valloc(); int rand(); main(argc, argv) char *argv[]; { register int pn, i, niter, delta; register char *pages; float sd = 10.0; int npages = 4096, pagesize, debug = 0; char *name; name = argv[0]; argc--, argv++; again: if (argc < 1) { usage: printf( "usage: %s [ -d ] [ -k #Kb ] [ -s standard-deviation ] iterations\n", name); exit(1); } if (strcmp(*argv, "-s") == 0) { argc--, argv++; if (argc < 1) goto usage; sscanf(*argv, "%f", &sd); if (sd <= 0) { printf("%s: Bad standard deviation.\n", *argv); exit(2); } argc--, argv++; goto again; } if (strcmp(*argv, "-k") == 0) { argc--, argv++; if (argc < 1) goto usage; npages = atoi(*argv); if (npages <= 0) { printf("%s: Bad virtual memory size.\n", *argv); exit(2); } argc--, argv++; goto again; } if (strcmp(*argv, "-d") == 0) { argc--, argv++; debug++; goto again; } niter = atoi(*argv); pagesize = getpagesize(); npages /= pagesize / 1024; pages = valloc(npages, pagesize); if (pages == (char *)0) { printf("Can't allocate %d pages (%2.1f megabytes).\n", npages, (npages*pagesize) / (1024. * 1024.)); exit(3); } if (pagesize != 1024) printf("Pagesize %dKb\n", pagesize / 1024); pn = 0; for (i = 0; i < niter; i++) { delta = gauss(sd, 0.0); while (pn + delta < 0 || pn + delta > npages) delta = gauss(sd, 0.0); pn += delta; if (debug) printf("touch page %d\n", pn); else pages[pn * pagesize] = 1; } } float gauss(sd, mean) float sd, mean; { register float qa, qb; qa = sqrt(log(rnd()) * -2.0); qb = 3.14159 * rnd(); return (qa * cos(qb) * sd + mean); } float rnd() { static int seed = 1; static int biggest = 0x7fffffff; return ((float)rand(seed) / (float)biggest); }