From nobody Mon Feb 9 19:47:54 2026 Received: from mailgw.kylinos.cn (mailgw.kylinos.cn [124.126.103.232]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4BCDC3803C3; Tue, 13 Jan 2026 08:28:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=124.126.103.232 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768292919; cv=none; b=na5Rvdxxai+8a5LOZ4CD6Z5yp0+Hgt13y4WkIx7xf+22kio+sL67rr3WLMjhbCmkZhEncgdMHteRgBx2wnNtCCwa6Tc5IctWK1r2mvJbWpfDDUgbBiZ+1uf4deHAKKrMr9WoJiw0uhjI67NUoU+m+FQgYhQSlC1a5Edi8upja4k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768292919; c=relaxed/simple; bh=lGKnYIpD5iPajFU0H5v2enpysWFcaB3u6bhBnKsgqQw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=hgTN6vk37yrBZEXUhx6q+FXypFHwtSClyoSpLJPEhQBwULSVa+agF6l7OIRU6BoDQpmJjh0lHSJfDWHSJA63DtsFqwcti8zwxgedBNZOAyXRKFAll+XoEpU0I2uurwXXBn03hlxDSm7AqOE5Qig+P+19WJybiCePLDVBLcSTXVI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn; spf=pass smtp.mailfrom=kylinos.cn; arc=none smtp.client-ip=124.126.103.232 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kylinos.cn X-UUID: d61ef7b8f05911f0a38c85956e01ac42-20260113 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.6,REQID:20aca996-3ffb-4c7c-936d-54af30a3665c,IP:0,UR L:0,TC:0,Content:-25,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTION :release,TS:-25 X-CID-META: VersionHash:a9d874c,CLOUDID:30b8f83c4b3fdd7a718fa5b9b3b72304,BulkI D:nil,BulkQuantity:0,Recheck:0,SF:81|82|102|850|898,TC:nil,Content:0|15|50 ,EDM:-3,IP:nil,URL:0,File:nil,RT:nil,Bulk:nil,QS:nil,BEC:nil,COL:0,OSI:0,O SA:0,AV:0,LES:1,SPR:NO,DKR:0,DKP:0,BRR:0,BRE:0,ARC:0 X-CID-BVR: 2,SSN|SDN X-CID-BAS: 2,SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: d61ef7b8f05911f0a38c85956e01ac42-20260113 X-User: jiangfeng@kylinos.cn Received: from localhost.localdomain [(10.44.16.150)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_256_GCM_SHA384 256/256) with ESMTP id 307928599; Tue, 13 Jan 2026 16:28:28 +0800 From: Feng Jiang To: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, kees@kernel.org, andy@kernel.org, akpm@linux-foundation.org, jiangfeng@kylinos.cn, ebiggers@kernel.org, martin.petersen@oracle.com, ardb@kernel.org, ajones@ventanamicro.com, conor.dooley@microchip.com, samuel.holland@sifive.com, linus.walleij@linaro.org, nathan@kernel.org Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2 09/14] lib/string_kunit: add performance benchmark for strnlen() Date: Tue, 13 Jan 2026 16:27:43 +0800 Message-Id: <20260113082748.250916-10-jiangfeng@kylinos.cn> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260113082748.250916-1-jiangfeng@kylinos.cn> References: <20260113082748.250916-1-jiangfeng@kylinos.cn> 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" Introduce a benchmark to compare the architecture-optimized strnlen() implementation against the generic C version (__generic_strnlen). Suggested-by: Andy Shevchenko Signed-off-by: Feng Jiang --- lib/tests/string_kunit.c | 48 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 47 insertions(+), 1 deletion(-) diff --git a/lib/tests/string_kunit.c b/lib/tests/string_kunit.c index 2266954ae5e0..6578b36213bc 100644 --- a/lib/tests/string_kunit.c +++ b/lib/tests/string_kunit.c @@ -20,7 +20,7 @@ #define STRING_TEST_MAX_LEN 128 #define STRING_TEST_MAX_OFFSET 16 =20 -#if defined(__HAVE_ARCH_STRLEN) +#if defined(__HAVE_ARCH_STRLEN) || defined(__HAVE_ARCH_STRNLEN) #define STRING_BENCH_ENABLED #endif =20 @@ -272,6 +272,49 @@ static void string_test_strnlen(struct kunit *test) } } =20 +#ifdef __HAVE_ARCH_STRNLEN +static void string_test_strnlen_bench(struct kunit *test) +{ + char *buf; + size_t buf_len, iters; + ktime_t start, end; + u64 time_arch, time_generic; + + buf_len =3D get_max_bench_len(bench_cases, ARRAY_SIZE(bench_cases)) + 1; + + buf =3D kunit_kzalloc(test, buf_len, GFP_KERNEL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buf); + + for (size_t i =3D 0; i < ARRAY_SIZE(bench_cases); i++) { + get_random_nonzero_bytes(buf, bench_cases[i].len); + buf[bench_cases[i].len] =3D '\0'; + + iters =3D bench_cases[i].iterations; + + /* 1. Benchmark the architecture-optimized version */ + start =3D ktime_get(); + for (unsigned int j =3D 0; j < iters; j++) { + OPTIMIZER_HIDE_VAR(buf); + (void)strnlen(buf, buf_len); + } + end =3D ktime_get(); + time_arch =3D ktime_to_ns(ktime_sub(end, start)); + + /* 2. Benchmark the generic C version */ + start =3D ktime_get(); + for (unsigned int j =3D 0; j < iters; j++) { + OPTIMIZER_HIDE_VAR(buf); + (void)__generic_strnlen(buf, buf_len); + } + end =3D ktime_get(); + time_generic =3D ktime_to_ns(ktime_sub(end, start)); + + string_bench_report(test, "strnlen", &bench_cases[i], + time_arch, time_generic); + } +} +#endif + static void string_test_strchr(struct kunit *test) { const char *test_string =3D "abcdefghijkl"; @@ -820,6 +863,9 @@ static struct kunit_case string_test_cases[] =3D { KUNIT_CASE(string_test_strlen_bench), #endif KUNIT_CASE(string_test_strnlen), +#ifdef __HAVE_ARCH_STRNLEN + KUNIT_CASE(string_test_strnlen_bench), +#endif KUNIT_CASE(string_test_strchr), KUNIT_CASE(string_test_strnchr), KUNIT_CASE(string_test_strrchr), --=20 2.25.1