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Diffstat (limited to 'fs/bcachefs/mean_and_variance_test.c')
| -rw-r--r-- | fs/bcachefs/mean_and_variance_test.c | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/fs/bcachefs/mean_and_variance_test.c b/fs/bcachefs/mean_and_variance_test.c new file mode 100644 index 000000000000..019583c3ca0e --- /dev/null +++ b/fs/bcachefs/mean_and_variance_test.c @@ -0,0 +1,240 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <kunit/test.h> + +#include "mean_and_variance.h" + +#define MAX_SQR (SQRT_U64_MAX*SQRT_U64_MAX) + +static void mean_and_variance_basic_test(struct kunit *test) +{ + struct mean_and_variance s = {}; + + mean_and_variance_update(&s, 2); + mean_and_variance_update(&s, 2); + + KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(s), 2); + KUNIT_EXPECT_EQ(test, mean_and_variance_get_variance(s), 0); + KUNIT_EXPECT_EQ(test, s.n, 2); + + mean_and_variance_update(&s, 4); + mean_and_variance_update(&s, 4); + + KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(s), 3); + KUNIT_EXPECT_EQ(test, mean_and_variance_get_variance(s), 1); + KUNIT_EXPECT_EQ(test, s.n, 4); +} + +/* + * Test values computed using a spreadsheet from the psuedocode at the bottom: + * https://fanf2.user.srcf.net/hermes/doc/antiforgery/stats.pdf + */ + +static void mean_and_variance_weighted_test(struct kunit *test) +{ + struct mean_and_variance_weighted s = { .weight = 2 }; + + mean_and_variance_weighted_update(&s, 10); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), 10); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 0); + + mean_and_variance_weighted_update(&s, 20); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), 12); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 18); + + mean_and_variance_weighted_update(&s, 30); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), 16); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 72); + + s = (struct mean_and_variance_weighted) { .weight = 2 }; + + mean_and_variance_weighted_update(&s, -10); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), -10); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 0); + + mean_and_variance_weighted_update(&s, -20); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), -12); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 18); + + mean_and_variance_weighted_update(&s, -30); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), -16); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 72); +} + +static void mean_and_variance_weighted_advanced_test(struct kunit *test) +{ + struct mean_and_variance_weighted s = { .weight = 8 }; + s64 i; + + for (i = 10; i <= 100; i += 10) + mean_and_variance_weighted_update(&s, i); + + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), 11); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 107); + + s = (struct mean_and_variance_weighted) { .weight = 8 }; + + for (i = -10; i >= -100; i -= 10) + mean_and_variance_weighted_update(&s, i); + + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), -11); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 107); +} + +static void do_mean_and_variance_test(struct kunit *test, + s64 initial_value, + s64 initial_n, + s64 n, + unsigned weight, + s64 *data, + s64 *mean, + s64 *stddev, + s64 *weighted_mean, + s64 *weighted_stddev) +{ + struct mean_and_variance mv = {}; + struct mean_and_variance_weighted vw = { .weight = weight }; + + for (unsigned i = 0; i < initial_n; i++) { + mean_and_variance_update(&mv, initial_value); + mean_and_variance_weighted_update(&vw, initial_value); + + KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(mv), initial_value); + KUNIT_EXPECT_EQ(test, mean_and_variance_get_stddev(mv), 0); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(vw), initial_value); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_stddev(vw),0); + } + + for (unsigned i = 0; i < n; i++) { + mean_and_variance_update(&mv, data[i]); + mean_and_variance_weighted_update(&vw, data[i]); + + KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(mv), mean[i]); + KUNIT_EXPECT_EQ(test, mean_and_variance_get_stddev(mv), stddev[i]); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(vw), weighted_mean[i]); + KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_stddev(vw),weighted_stddev[i]); + } + + KUNIT_EXPECT_EQ(test, mv.n, initial_n + n); +} + +/* Test behaviour with a single outlier, then back to steady state: */ +static void mean_and_variance_test_1(struct kunit *test) +{ + s64 d[] = { 100, 10, 10, 10, 10, 10, 10 }; + s64 mean[] = { 22, 21, 20, 19, 18, 17, 16 }; + s64 stddev[] = { 32, 29, 28, 27, 26, 25, 24 }; + s64 weighted_mean[] = { 32, 27, 22, 19, 17, 15, 14 }; + s64 weighted_stddev[] = { 38, 35, 31, 27, 24, 21, 18 }; + + do_mean_and_variance_test(test, 10, 6, ARRAY_SIZE(d), 2, + d, mean, stddev, weighted_mean, weighted_stddev); +} + +static void mean_and_variance_test_2(struct kunit *test) +{ + s64 d[] = { 100, 10, 10, 10, 10, 10, 10 }; + s64 mean[] = { 10, 10, 10, 10, 10, 10, 10 }; + s64 stddev[] = { 9, 9, 9, 9, 9, 9, 9 }; + s64 weighted_mean[] = { 32, 27, 22, 19, 17, 15, 14 }; + s64 weighted_stddev[] = { 38, 35, 31, 27, 24, 21, 18 }; + + do_mean_and_variance_test(test, 10, 6, ARRAY_SIZE(d), 2, + d, mean, stddev, weighted_mean, weighted_stddev); +} + +/* Test behaviour where we switch from one steady state to another: */ +static void mean_and_variance_test_3(struct kunit *test) +{ + s64 d[] = { 100, 100, 100, 100, 100 }; + s64 mean[] = { 22, 32, 40, 46, 50 }; + s64 stddev[] = { 32, 39, 42, 44, 45 }; + s64 weighted_mean[] = { 32, 49, 61, 71, 78 }; + s64 weighted_stddev[] = { 38, 44, 44, 41, 38 }; + + do_mean_and_variance_test(test, 10, 6, ARRAY_SIZE(d), 2, + d, mean, stddev, weighted_mean, weighted_stddev); +} + +static void mean_and_variance_test_4(struct kunit *test) +{ + s64 d[] = { 100, 100, 100, 100, 100 }; + s64 mean[] = { 10, 11, 12, 13, 14 }; + s64 stddev[] = { 9, 13, 15, 17, 19 }; + s64 weighted_mean[] = { 32, 49, 61, 71, 78 }; + s64 weighted_stddev[] = { 38, 44, 44, 41, 38 }; + + do_mean_and_variance_test(test, 10, 6, ARRAY_SIZE(d), 2, + d, mean, stddev, weighted_mean, weighted_stddev); +} + +static void mean_and_variance_fast_divpow2(struct kunit *test) +{ + s64 i; + u8 d; + + for (i = 0; i < 100; i++) { + d = 0; + KUNIT_EXPECT_EQ(test, fast_divpow2(i, d), div_u64(i, 1LLU << d)); + KUNIT_EXPECT_EQ(test, abs(fast_divpow2(-i, d)), div_u64(i, 1LLU << d)); + for (d = 1; d < 32; d++) { + KUNIT_EXPECT_EQ_MSG(test, abs(fast_divpow2(i, d)), + div_u64(i, 1 << d), "%lld %u", i, d); + KUNIT_EXPECT_EQ_MSG(test, abs(fast_divpow2(-i, d)), + div_u64(i, 1 << d), "%lld %u", -i, d); + } + } +} + +static void mean_and_variance_u128_basic_test(struct kunit *test) +{ + u128_u a = u64s_to_u128(0, U64_MAX); + u128_u a1 = u64s_to_u128(0, 1); + u128_u b = u64s_to_u128(1, 0); + u128_u c = u64s_to_u128(0, 1LLU << 63); + u128_u c2 = u64s_to_u128(U64_MAX, U64_MAX); + + KUNIT_EXPECT_EQ(test, u128_hi(u128_add(a, a1)), 1); + KUNIT_EXPECT_EQ(test, u128_lo(u128_add(a, a1)), 0); + KUNIT_EXPECT_EQ(test, u128_hi(u128_add(a1, a)), 1); + KUNIT_EXPECT_EQ(test, u128_lo(u128_add(a1, a)), 0); + + KUNIT_EXPECT_EQ(test, u128_lo(u128_sub(b, a1)), U64_MAX); + KUNIT_EXPECT_EQ(test, u128_hi(u128_sub(b, a1)), 0); + + KUNIT_EXPECT_EQ(test, u128_hi(u128_shl(c, 1)), 1); + KUNIT_EXPECT_EQ(test, u128_lo(u128_shl(c, 1)), 0); + + KUNIT_EXPECT_EQ(test, u128_hi(u128_square(U64_MAX)), U64_MAX - 1); + KUNIT_EXPECT_EQ(test, u128_lo(u128_square(U64_MAX)), 1); + + KUNIT_EXPECT_EQ(test, u128_lo(u128_div(b, 2)), 1LLU << 63); + + KUNIT_EXPECT_EQ(test, u128_hi(u128_div(c2, 2)), U64_MAX >> 1); + KUNIT_EXPECT_EQ(test, u128_lo(u128_div(c2, 2)), U64_MAX); + + KUNIT_EXPECT_EQ(test, u128_hi(u128_div(u128_shl(u64_to_u128(U64_MAX), 32), 2)), U32_MAX >> 1); + KUNIT_EXPECT_EQ(test, u128_lo(u128_div(u128_shl(u64_to_u128(U64_MAX), 32), 2)), U64_MAX << 31); +} + +static struct kunit_case mean_and_variance_test_cases[] = { + KUNIT_CASE(mean_and_variance_fast_divpow2), + KUNIT_CASE(mean_and_variance_u128_basic_test), + KUNIT_CASE(mean_and_variance_basic_test), + KUNIT_CASE(mean_and_variance_weighted_test), + KUNIT_CASE(mean_and_variance_weighted_advanced_test), + KUNIT_CASE(mean_and_variance_test_1), + KUNIT_CASE(mean_and_variance_test_2), + KUNIT_CASE(mean_and_variance_test_3), + KUNIT_CASE(mean_and_variance_test_4), + {} +}; + +static struct kunit_suite mean_and_variance_test_suite = { + .name = "mean and variance tests", + .test_cases = mean_and_variance_test_cases +}; + +kunit_test_suite(mean_and_variance_test_suite); + +MODULE_AUTHOR("Daniel B. Hill"); +MODULE_LICENSE("GPL"); |