11 #include "../minmax.h"
14 #define ZIPF_MAX_GEN 10000000
16 static void zipf_update(struct zipf_state *zs)
21 log_info("fio: generating zetan for theta=%f, ranges=%lu\n", zs->theta, zs->nranges);
24 * It can become very costly to generate long sequences. Just cap it at
25 * 10M max, that should be doable in 1-2s on even slow machines. Precision
26 * will take a slight hit, but nothing major.
28 to_gen = min(zs->nranges, ZIPF_MAX_GEN);
30 for (i = 0; i < to_gen; i++)
31 zs->zetan += pow(1.0 / (double) (i + 1), zs->theta);
34 static void shared_rand_init(struct zipf_state *zs, unsigned long nranges,
37 memset(zs, 0, sizeof(*zs));
38 zs->nranges = nranges;
40 init_rand_seed(&zs->rand, seed);
41 zs->rand_off = __rand(&zs->rand);
44 void zipf_init(struct zipf_state *zs, unsigned long nranges, double theta,
47 shared_rand_init(zs, nranges, seed);
50 zs->zeta2 = pow(1.0, zs->theta) + pow(0.5, zs->theta);
55 unsigned long long zipf_next(struct zipf_state *zs)
57 double alpha, eta, rand_uni, rand_z;
58 unsigned long long n = zs->nranges;
59 unsigned long long val;
61 alpha = 1.0 / (1.0 - zs->theta);
62 eta = (1.0 - pow(2.0 / n, 1.0 - zs->theta)) / (1.0 - zs->zeta2 / zs->zetan);
64 rand_uni = (double) __rand(&zs->rand) / (double) FRAND_MAX;
65 rand_z = rand_uni * zs->zetan;
69 else if (rand_z < (1.0 + pow(0.5, zs->theta)))
72 val = 1 + (unsigned long long)(n * pow(eta*rand_uni - eta + 1.0, alpha));
74 return (__hash_long(val - 1) + zs->rand_off) % zs->nranges;
77 void pareto_init(struct zipf_state *zs, unsigned long nranges, double h,
80 shared_rand_init(zs, nranges, seed);
81 zs->pareto_pow = log(h) / log(1.0 - h);
84 unsigned long long pareto_next(struct zipf_state *zs)
86 double rand = (double) __rand(&zs->rand) / (double) FRAND_MAX;
87 unsigned long long n = zs->nranges - 1;
89 return (__hash_long(n * pow(rand, zs->pareto_pow)) + zs->rand_off) % zs->nranges;