From: Milan Tripkovic <[email protected]>

Extend the string benchmarking suite to include memcmp().
Extend the string unit test to include memcmp().

Signed-off-by: Milan Tripkovic <[email protected]>
---
 lib/tests/string_kunit.c | 116 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)

diff --git a/lib/tests/string_kunit.c b/lib/tests/string_kunit.c
index 0819ace5b..95d65c25b 100644
--- a/lib/tests/string_kunit.c
+++ b/lib/tests/string_kunit.c
@@ -881,6 +881,120 @@ static void string_bench_strrchr(struct kunit *test)
        STRING_BENCH_BUF(test, buf, len, strrchr, buf, '\0');
 }
 
+static void string_test_memcmp(struct kunit *test)
+{
+       const unsigned int max_offset = 16;
+       const unsigned int max_len = 32;
+       const unsigned int buf_size = max_offset + max_len + 32;
+       u8 *buf1, *buf2;
+       unsigned int i, j, len, k;
+       int res;
+
+       buf1 = kunit_kzalloc(test, buf_size, GFP_KERNEL);
+       buf2 = kunit_kzalloc(test, buf_size, GFP_KERNEL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buf1);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buf2);
+
+       for (i = 0; i < max_offset; i++) {
+               for (j = 0; j < max_offset; j++) {
+                       for (len = 0; len <= max_len; len++) {
+                               memset(buf1, 'A', buf_size);
+                               memset(buf2, 'A', buf_size);
+                               KUNIT_EXPECT_EQ_MSG(test, memcmp(buf1 + i, buf2 
+ j, len), 0,
+                                                   "Should be equal: i:%u j:%u 
len:%u", i, j, len);
+                               for (k = 0; k < len; k++) {
+                                       memset(buf1, 'A', buf_size);
+                                       memset(buf2, 'A', buf_size);
+                                       buf2[j + k] = 'B';
+                                       res = memcmp(buf1 + i, buf2 + j, len);
+                                       KUNIT_EXPECT_NE_MSG(test, res, 0,
+                                                           "Should detect 
difference at k:%u (i:%u j:%u len:%u)",
+                                               k, i, j, len);
+                                       if (buf1[i + k] < buf2[j + k])
+                                               KUNIT_EXPECT_LT(test, res, 0);
+                                       else
+                                               KUNIT_EXPECT_GT(test, res, 0);
+                               }
+                       }
+               }
+       }
+}
+
+static void do_string_bench_memcmp(struct kunit *test)
+{
+       char *buf1 = NULL;
+       char *buf2 = NULL;
+       const u64 lengths[] = { 1, 7, 8, 16, 32, 64, 128, 512, 1024, 4096 };
+       const int offsets[] = { 0, 1, 3, 7 };
+       const u64 max_len = 4096 + 64;
+       unsigned int w, o, i;
+       unsigned int off;
+       u64 len;
+       char *p1;
+       char *p2;
+       u64 iterations;
+       u64 elapsed;
+       u64 ns_per_call;
+       u64 mbps;
+       u64 j;
+
+       buf1 = vmalloc(max_len);
+       buf2 = vmalloc(max_len);
+
+       if (!buf1 || !buf2) {
+               vfree(buf1);
+               vfree(buf2);
+               kunit_err(test, "vmalloc failed\n");
+               return;
+       }
+
+       memset(buf1, 'A', max_len);
+       memset(buf2, 'A', max_len);
+
+       for (w = 0; w < 100000U; w++)
+               (void)memcmp(buf1, buf2, 4096);
+
+       for (o = 0; o < ARRAY_SIZE(offsets); o++) {
+               off = offsets[o];
+
+               for (i = 0; i < ARRAY_SIZE(lengths); i++) {
+                       len = lengths[i];
+                       p1 = buf1;
+                       p2 = buf2 + off;
+                       iterations = (len < 512) ? 100000ULL : 10000ULL;
+
+                       for (j = 0; j < iterations; j++) {
+                               (void)memcmp(p1, p2, len);
+                               barrier();
+                       }
+
+                       elapsed = STRING_BENCH(iterations, memcmp, p1, p2, len);
+                       ns_per_call = div_u64(elapsed, iterations);
+                       mbps = len ? div_u64(iterations * len * (NSEC_PER_SEC / 
MEGA), elapsed) : 0;
+
+                       if (off == 0) {
+                               kunit_info(test, "bench_memcmp_aligned: 
len=%-4llu: %llu MB/s (%llu ns/call)\n",
+                                          len, mbps, ns_per_call);
+                       } else {
+                               kunit_info(test, 
"bench_memcmp_unaligned(off=%u): len=%-4llu: %llu MB/s (%llu ns/call)\n",
+                                          off, len, mbps, ns_per_call);
+                       }
+               }
+       }
+
+       vfree(buf1);
+       vfree(buf2);
+}
+
+static void string_bench_memcmp(struct kunit *test)
+{
+       if (!IS_ENABLED(CONFIG_STRING_KUNIT_BENCH)) {
+               kunit_skip(test, "CONFIG_STRING_KUNIT_BENCH not enabled");
+               return;
+       }
+       do_string_bench_memcmp(test);
+}
+
 static struct kunit_case string_test_cases[] = {
        KUNIT_CASE(string_test_memset16),
        KUNIT_CASE(string_test_memset32),
@@ -910,6 +1024,8 @@ static struct kunit_case string_test_cases[] = {
        KUNIT_CASE(string_bench_strnlen),
        KUNIT_CASE(string_bench_strchr),
        KUNIT_CASE(string_bench_strrchr),
+       KUNIT_CASE(string_test_memcmp),
+       KUNIT_CASE_SLOW(string_bench_memcmp),
        {}
 };
 
-- 
2.43.0


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