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1// SPDX-License-Identifier: GPL-2.02#include <kunit/test.h>3 4#include "mean_and_variance.h"5 6#define MAX_SQR (SQRT_U64_MAX*SQRT_U64_MAX)7 8static void mean_and_variance_basic_test(struct kunit *test)9{10 struct mean_and_variance s = {};11 12 mean_and_variance_update(&s, 2);13 mean_and_variance_update(&s, 2);14 15 KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(s), 2);16 KUNIT_EXPECT_EQ(test, mean_and_variance_get_variance(s), 0);17 KUNIT_EXPECT_EQ(test, s.n, 2);18 19 mean_and_variance_update(&s, 4);20 mean_and_variance_update(&s, 4);21 22 KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(s), 3);23 KUNIT_EXPECT_EQ(test, mean_and_variance_get_variance(s), 1);24 KUNIT_EXPECT_EQ(test, s.n, 4);25}26 27/*28 * Test values computed using a spreadsheet from the psuedocode at the bottom:29 * https://fanf2.user.srcf.net/hermes/doc/antiforgery/stats.pdf30 */31 32static void mean_and_variance_weighted_test(struct kunit *test)33{34 struct mean_and_variance_weighted s = { };35 36 mean_and_variance_weighted_update(&s, 10, false, 2);37 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s, 2), 10);38 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s, 2), 0);39 40 mean_and_variance_weighted_update(&s, 20, true, 2);41 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s, 2), 12);42 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s, 2), 18);43 44 mean_and_variance_weighted_update(&s, 30, true, 2);45 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s, 2), 16);46 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s, 2), 72);47 48 s = (struct mean_and_variance_weighted) { };49 50 mean_and_variance_weighted_update(&s, -10, false, 2);51 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s, 2), -10);52 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s, 2), 0);53 54 mean_and_variance_weighted_update(&s, -20, true, 2);55 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s, 2), -12);56 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s, 2), 18);57 58 mean_and_variance_weighted_update(&s, -30, true, 2);59 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s, 2), -16);60 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s, 2), 72);61}62 63static void mean_and_variance_weighted_advanced_test(struct kunit *test)64{65 struct mean_and_variance_weighted s = { };66 bool initted = false;67 s64 i;68 69 for (i = 10; i <= 100; i += 10) {70 mean_and_variance_weighted_update(&s, i, initted, 8);71 initted = true;72 }73 74 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s, 8), 11);75 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s, 8), 107);76 77 s = (struct mean_and_variance_weighted) { };78 initted = false;79 80 for (i = -10; i >= -100; i -= 10) {81 mean_and_variance_weighted_update(&s, i, initted, 8);82 initted = true;83 }84 85 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s, 8), -11);86 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s, 8), 107);87}88 89static void do_mean_and_variance_test(struct kunit *test,90 s64 initial_value,91 s64 initial_n,92 s64 n,93 unsigned weight,94 s64 *data,95 s64 *mean,96 s64 *stddev,97 s64 *weighted_mean,98 s64 *weighted_stddev)99{100 struct mean_and_variance mv = {};101 struct mean_and_variance_weighted vw = { };102 103 for (unsigned i = 0; i < initial_n; i++) {104 mean_and_variance_update(&mv, initial_value);105 mean_and_variance_weighted_update(&vw, initial_value, false, weight);106 107 KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(mv), initial_value);108 KUNIT_EXPECT_EQ(test, mean_and_variance_get_stddev(mv), 0);109 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(vw, weight), initial_value);110 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_stddev(vw, weight),0);111 }112 113 for (unsigned i = 0; i < n; i++) {114 mean_and_variance_update(&mv, data[i]);115 mean_and_variance_weighted_update(&vw, data[i], true, weight);116 117 KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(mv), mean[i]);118 KUNIT_EXPECT_EQ(test, mean_and_variance_get_stddev(mv), stddev[i]);119 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(vw, weight), weighted_mean[i]);120 KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_stddev(vw, weight),weighted_stddev[i]);121 }122 123 KUNIT_EXPECT_EQ(test, mv.n, initial_n + n);124}125 126/* Test behaviour with a single outlier, then back to steady state: */127static void mean_and_variance_test_1(struct kunit *test)128{129 s64 d[] = { 100, 10, 10, 10, 10, 10, 10 };130 s64 mean[] = { 22, 21, 20, 19, 18, 17, 16 };131 s64 stddev[] = { 32, 29, 28, 27, 26, 25, 24 };132 s64 weighted_mean[] = { 32, 27, 22, 19, 17, 15, 14 };133 s64 weighted_stddev[] = { 38, 35, 31, 27, 24, 21, 18 };134 135 do_mean_and_variance_test(test, 10, 6, ARRAY_SIZE(d), 2,136 d, mean, stddev, weighted_mean, weighted_stddev);137}138 139/* Test behaviour where we switch from one steady state to another: */140static void mean_and_variance_test_2(struct kunit *test)141{142 s64 d[] = { 100, 100, 100, 100, 100 };143 s64 mean[] = { 22, 32, 40, 46, 50 };144 s64 stddev[] = { 32, 39, 42, 44, 45 };145 s64 weighted_mean[] = { 32, 49, 61, 71, 78 };146 s64 weighted_stddev[] = { 38, 44, 44, 41, 38 };147 148 do_mean_and_variance_test(test, 10, 6, ARRAY_SIZE(d), 2,149 d, mean, stddev, weighted_mean, weighted_stddev);150}151 152static void mean_and_variance_fast_divpow2(struct kunit *test)153{154 s64 i;155 u8 d;156 157 for (i = 0; i < 100; i++) {158 d = 0;159 KUNIT_EXPECT_EQ(test, fast_divpow2(i, d), div_u64(i, 1LLU << d));160 KUNIT_EXPECT_EQ(test, abs(fast_divpow2(-i, d)), div_u64(i, 1LLU << d));161 for (d = 1; d < 32; d++) {162 KUNIT_EXPECT_EQ_MSG(test, abs(fast_divpow2(i, d)),163 div_u64(i, 1 << d), "%lld %u", i, d);164 KUNIT_EXPECT_EQ_MSG(test, abs(fast_divpow2(-i, d)),165 div_u64(i, 1 << d), "%lld %u", -i, d);166 }167 }168}169 170static void mean_and_variance_u128_basic_test(struct kunit *test)171{172 u128_u a = u64s_to_u128(0, U64_MAX);173 u128_u a1 = u64s_to_u128(0, 1);174 u128_u b = u64s_to_u128(1, 0);175 u128_u c = u64s_to_u128(0, 1LLU << 63);176 u128_u c2 = u64s_to_u128(U64_MAX, U64_MAX);177 178 KUNIT_EXPECT_EQ(test, u128_hi(u128_add(a, a1)), 1);179 KUNIT_EXPECT_EQ(test, u128_lo(u128_add(a, a1)), 0);180 KUNIT_EXPECT_EQ(test, u128_hi(u128_add(a1, a)), 1);181 KUNIT_EXPECT_EQ(test, u128_lo(u128_add(a1, a)), 0);182 183 KUNIT_EXPECT_EQ(test, u128_lo(u128_sub(b, a1)), U64_MAX);184 KUNIT_EXPECT_EQ(test, u128_hi(u128_sub(b, a1)), 0);185 186 KUNIT_EXPECT_EQ(test, u128_hi(u128_shl(c, 1)), 1);187 KUNIT_EXPECT_EQ(test, u128_lo(u128_shl(c, 1)), 0);188 189 KUNIT_EXPECT_EQ(test, u128_hi(u128_square(U64_MAX)), U64_MAX - 1);190 KUNIT_EXPECT_EQ(test, u128_lo(u128_square(U64_MAX)), 1);191 192 KUNIT_EXPECT_EQ(test, u128_lo(u128_div(b, 2)), 1LLU << 63);193 194 KUNIT_EXPECT_EQ(test, u128_hi(u128_div(c2, 2)), U64_MAX >> 1);195 KUNIT_EXPECT_EQ(test, u128_lo(u128_div(c2, 2)), U64_MAX);196 197 KUNIT_EXPECT_EQ(test, u128_hi(u128_div(u128_shl(u64_to_u128(U64_MAX), 32), 2)), U32_MAX >> 1);198 KUNIT_EXPECT_EQ(test, u128_lo(u128_div(u128_shl(u64_to_u128(U64_MAX), 32), 2)), U64_MAX << 31);199}200 201static struct kunit_case mean_and_variance_test_cases[] = {202 KUNIT_CASE(mean_and_variance_fast_divpow2),203 KUNIT_CASE(mean_and_variance_u128_basic_test),204 KUNIT_CASE(mean_and_variance_basic_test),205 KUNIT_CASE(mean_and_variance_weighted_test),206 KUNIT_CASE(mean_and_variance_weighted_advanced_test),207 KUNIT_CASE(mean_and_variance_test_1),208 KUNIT_CASE(mean_and_variance_test_2),209 {}210};211 212static struct kunit_suite mean_and_variance_test_suite = {213 .name = "mean and variance tests",214 .test_cases = mean_and_variance_test_cases215};216 217kunit_test_suite(mean_and_variance_test_suite);218 219MODULE_AUTHOR("Daniel B. Hill");220MODULE_DESCRIPTION("bcachefs filesystem mean and variance unit tests");221MODULE_LICENSE("GPL");222