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// SPDX-License-Identifier: GPL-2.0
#include <kunit/test.h>
#include <linux/stats.h>
#define MAX_SQR (SQRT_U64_MAX*SQRT_U64_MAX)
static void stats_basic_test(struct kunit *test)
{
struct mean_and_variance s = {};
s = stats_update(s, 2);
s = stats_update(s, 2);
KUNIT_EXPECT_EQ(test, stats_mean(s), 2);
KUNIT_EXPECT_EQ(test, stats_variance(s), 0);
KUNIT_EXPECT_EQ(test, s.n, 2);
s = stats_update(s, 4);
s = stats_update(s, 4);
KUNIT_EXPECT_EQ(test, stats_mean(s), 3);
KUNIT_EXPECT_EQ(test, stats_variance(s), 1);
KUNIT_EXPECT_EQ(test, s.n, 4);
/*
* Test overflow bounds
*/
s = (struct mean_and_variance){};
s = stats_update(s, SQRT_U64_MAX);
KUNIT_EXPECT_EQ_MSG(test,
s.sum_squares,
MAX_SQR,
"%llu == %llu, sqrt: %llu == %llu",
s.sum_squares,
MAX_SQR,
int_sqrt64(s.sum_squares),
SQRT_U64_MAX);
s = (struct mean_and_variance){};
s = stats_update(s, -(s64)SQRT_U64_MAX);
KUNIT_EXPECT_EQ_MSG(test,
s.sum_squares,
MAX_SQR,
"%llu == %llu, sqrt: %llu == %llu",
s.sum_squares,
MAX_SQR,
int_sqrt64(s.sum_squares),
SQRT_U64_MAX);
s = (struct mean_and_variance){};
s = stats_update(s, (SQRT_U64_MAX + 1));
KUNIT_EXPECT_LT(test, s.sum_squares, MAX_SQR);
s = (struct mean_and_variance){};
s = stats_update(s, (-(s64)SQRT_U64_MAX) - 1);
KUNIT_EXPECT_LT(test, s.sum_squares, MAX_SQR);
}
/*
* Test values computed using a spreadsheet from the psuedocode at the bottom:
* https://fanf2.user.srcf.net/hermes/doc/antiforgery/stats.pdf
*/
static void stats_ewm_test(struct kunit *test)
{
struct mean_and_variance_ewm s = {};
s.w = 2;
s = stats_ewm_update(s, 10);
KUNIT_EXPECT_EQ(test, stats_ewm_mean(s), 10);
KUNIT_EXPECT_EQ(test, stats_ewm_variance(s), 0);
s = stats_ewm_update(s, 20);
KUNIT_EXPECT_EQ(test, stats_ewm_mean(s), 12);
KUNIT_EXPECT_EQ(test, stats_ewm_variance(s), 18);
s = stats_ewm_update(s, 30);
KUNIT_EXPECT_EQ(test, stats_ewm_mean(s), 16);
KUNIT_EXPECT_EQ(test, stats_ewm_variance(s), 71);
s = (struct mean_and_variance_ewm){};
s.w = 2;
s = stats_ewm_update(s, -10);
KUNIT_EXPECT_EQ(test, stats_ewm_mean(s), -10);
KUNIT_EXPECT_EQ(test, stats_ewm_variance(s), 0);
s = stats_ewm_update(s, -20);
KUNIT_EXPECT_EQ(test, stats_ewm_mean(s), -12);
KUNIT_EXPECT_EQ(test, stats_ewm_variance(s), 18);
s = stats_ewm_update(s, -30);
KUNIT_EXPECT_EQ(test, stats_ewm_mean(s), -16);
KUNIT_EXPECT_EQ(test, stats_ewm_variance(s), 71);
}
static void stats_ewm_advanced_test(struct kunit *test)
{
struct mean_and_variance_ewm s = {};
s64 i;
s.w = 8;
for (i = 10; i <= 100; i += 10)
s = stats_ewm_update(s, i);
KUNIT_EXPECT_EQ(test, stats_ewm_mean(s), 11);
KUNIT_EXPECT_EQ(test, stats_ewm_variance(s), 107);
s = (struct mean_and_variance_ewm){};
s.w = 8;
for (i = -10; i >= -100; i -= 10)
s = stats_ewm_update(s, i);
KUNIT_EXPECT_EQ(test, stats_ewm_mean(s), -11);
KUNIT_EXPECT_EQ(test, stats_ewm_variance(s), 107);
}
static void stats_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 struct kunit_case stats_test_cases[] = {
KUNIT_CASE(stats_basic_test),
KUNIT_CASE(stats_ewm_test),
KUNIT_CASE(stats_ewm_advanced_test),
KUNIT_CASE(stats_fast_divpow2),
{}
};
static struct kunit_suite stats_test_suite = {
.name = "statistics",
.test_cases = stats_test_cases
};
kunit_test_suite(stats_test_suite);
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