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[37.117.189.76]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4361805815esm9171003f8f.20.2026.02.04.15.22.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Feb 2026 15:22:01 -0800 (PST) From: Matteo Croce X-Google-Original-From: Matteo Croce To: linux-kernel@vger.kernel.org, Andrew Morton , David Laight Subject: [PATCH v4] KUnit: memcpy: add benchmark Date: Thu, 5 Feb 2026 00:21:59 +0100 Message-ID: <20260204232159.12046-1-teknoraver@meta.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add optional benchmarks for memcpy() and memmove() functions. Each benchmark is run with different size and both aligned and unaligned buffers, to spot unaligned issues on platforms where they have a noticeable performance impact. Sample output on a RISC-V machine: # modprobe memcpy_kunit KTAP version 1 1..1 KTAP version 1 # Subtest: memcpy # module: memcpy_kunit 1..8 [...] # memcpy_bench_test: memcpy: aligned copy of len 2: 6 MB/s # memcpy_bench_test: memcpy: unaligned copy of len 2: 6 MB/s # memcpy_bench_test: memcpy: aligned copy of len 64: 179 MB/s # memcpy_bench_test: memcpy: unaligned copy of len 64: 170 MB/s # memcpy_bench_test: memcpy: aligned copy of len 256: 697 MB/s # memcpy_bench_test: memcpy: unaligned copy of len 256: 421 MB/s # memcpy_bench_test: memcpy: aligned copy of len 4194304: 935 MB/s # memcpy_bench_test: memcpy: unaligned copy of len 4194304: 333 MB/s # memcpy_bench_test.speed: slow ok 7 memcpy_bench_test # memmove_bench_test: memmove: aligned move of len 64: 162 MB/s # memmove_bench_test: memmove: unaligned move of len 64: 162 MB/s # memmove_bench_test: memmove: aligned move of len 256: 647 MB/s # memmove_bench_test: memmove: unaligned move of len 256: 647 MB/s # memmove_bench_test: memmove: aligned move of len 4194304: 1540 MB/s # memmove_bench_test: memmove: unaligned move of len 4194304: 1557 MB/s # memmove_bench_test.speed: slow ok 8 memmove_bench_test # memcpy: pass:8 fail:0 skip:0 total:8 # Totals: pass:8 fail:0 skip:0 total:8 ok 1 memcpy Signed-off-by: Matteo Croce --- lib/Kconfig.debug | 9 ++++ lib/tests/memcpy_kunit.c | 107 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 116 insertions(+) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index ba36939fda79..02868c4397cb 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2880,6 +2880,15 @@ config MEMCPY_KUNIT_TEST =20 If unsure, say N. =20 +config MEMCPY_KUNIT_BENCHMARK + bool "Benchmark string functions" + depends on MEMCPY_KUNIT_TEST + help + A benchmark for memcpy() and memmove() functions, + with both aligned and unaligned buffers. + + If unsure, say N. + config IS_SIGNED_TYPE_KUNIT_TEST tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS depends on KUNIT diff --git a/lib/tests/memcpy_kunit.c b/lib/tests/memcpy_kunit.c index d36933554e46..e7588b868125 100644 --- a/lib/tests/memcpy_kunit.c +++ b/lib/tests/memcpy_kunit.c @@ -493,6 +493,109 @@ static void memmove_overlap_test(struct kunit *test) } } =20 +#ifdef CONFIG_MEMCPY_KUNIT_BENCHMARK + +#define COPIES_NUM 100 + +static void memcpy_bench_size_align(struct kunit *test, int size, bool una= lign) +{ + u64 start, end, total_ns =3D 0; + char *dst, *src; + int ret =3D 0; + + dst =3D kzalloc(size, GFP_KERNEL); + if (!dst) { + ret =3D -ENOMEM; + goto out; + } + + src =3D kzalloc(size, GFP_KERNEL); + if (!src) { + ret =3D -ENOMEM; + goto out_free; + } + + for (int i =3D 0; i < COPIES_NUM; i++) { + local_irq_disable(); + start =3D ktime_get_ns(); + memcpy(dst + unalign, src, size - unalign); + end =3D ktime_get_ns(); + local_irq_enable(); + total_ns +=3D end - start; + } + + /* Avoid division by zero */ + if (!total_ns) + total_ns =3D 1; + + kunit_info(test, "memcpy: %saligned copy of len %d: %lld MB/s\n", + unalign ? "un" : "", size, + (COPIES_NUM * size * 1000000000ULL / total_ns) / (1024 * 1024)); + + kfree(src); + +out_free: + kfree(dst); + +out: + KUNIT_ASSERT_EQ(test, ret, 0); +} + +static void memcpy_bench_size(struct kunit *test, int size) +{ + memcpy_bench_size_align(test, size, false); + memcpy_bench_size_align(test, size, true); +} + +static void memcpy_bench_test(struct kunit *test) +{ + memcpy_bench_size(test, 2); + memcpy_bench_size(test, 64); + memcpy_bench_size(test, 256); + memcpy_bench_size(test, PAGE_SIZE << MAX_PAGE_ORDER); +} + +static void memmove_bench_size_align(struct kunit *test, int size, bool un= align) +{ + u64 start, end, total_ns =3D 0; + char *buf; + const int shift =3D size / 10; + + buf =3D kzalloc(size, GFP_KERNEL); + KUNIT_ASSERT_NOT_NULL(test, buf); + + for (int i =3D 0; i < COPIES_NUM; i++) { + local_irq_disable(); + start =3D ktime_get_ns(); + memmove(buf + shift + unalign, buf, size - shift - unalign); + end =3D ktime_get_ns(); + local_irq_enable(); + total_ns +=3D end - start; + } + + if (!total_ns) + total_ns =3D 1; + + kunit_info(test, "memmove: %saligned move of len %d: %lld MB/s\n", + unalign ? "un" : "", size, + (COPIES_NUM * (size - shift) * 1000000000ULL / total_ns) / (1024 * 10= 24)); + kfree(buf); +} + +static void memmove_bench_size(struct kunit *test, int size) +{ + memmove_bench_size_align(test, size, false); + memmove_bench_size_align(test, size, true); +} + +static void memmove_bench_test(struct kunit *test) +{ + memmove_bench_size(test, 64); + memmove_bench_size(test, 256); + memmove_bench_size(test, PAGE_SIZE << MAX_PAGE_ORDER); +} +#endif + static struct kunit_case memcpy_test_cases[] =3D { KUNIT_CASE(memset_test), KUNIT_CASE(memcpy_test), @@ -500,6 +603,10 @@ static struct kunit_case memcpy_test_cases[] =3D { KUNIT_CASE_SLOW(memmove_test), KUNIT_CASE_SLOW(memmove_large_test), KUNIT_CASE_SLOW(memmove_overlap_test), +#ifdef CONFIG_MEMCPY_KUNIT_BENCHMARK + KUNIT_CASE_SLOW(memcpy_bench_test), + KUNIT_CASE_SLOW(memmove_bench_test), +#endif {} }; =20 --=20 2.52.0