From nobody Tue Feb 10 04:12:58 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 DEC5137FF7C; Tue, 13 Jan 2026 08:28:34 +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=1768292918; cv=none; b=WXM4U90aXFcPnZWAppETOjIWLXnLSVDOQFq16wwgPa05sYr07hvXMfNvWm//SDVd9K6KERqjdanQhE86KPEAtdxNipqGYWUZWMGgsQ3AjxQSe+BO5ZKob7XtelP0dUlbeuIbq/iGmzZjrey4FEKFxkoEMClBOb19yThoKaasYoI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768292918; c=relaxed/simple; bh=cd2Au7zD0NRrQcN2SISsvZ4+SPhtuTLZeSAzYWRt8kg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=khcescb+YsUnnmlNx7qudcP+puN9o0S4l8Un3zeSNS8IQTv0MK/EXj3oRj2cq9QIxMkUqD7nRvIu03iQaDa7/zzRBHubFCPGhs4f9O0ai68QYsH1nRmwf6uBRSEDcBYBvGCKDloDfnrZLY11qin9g1wcyFrJCl8mpPnrJ4DjAho= 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: d741bc8ef05911f0a38c85956e01ac42-20260113 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.6,REQID:9154393b-57e9-4d90-9535-5debdf92c8db,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:3ab1f4e58411f53bcc71218cd9959621,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: d741bc8ef05911f0a38c85956e01ac42-20260113 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 1298105090; Tue, 13 Jan 2026 16:28:30 +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 11/14] lib/string_kunit: add performance benchmark for strrchr() Date: Tue, 13 Jan 2026 16:27:45 +0800 Message-Id: <20260113082748.250916-12-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 strrchr() implementation against the generic C version (__generic_strrchr). Suggested-by: Andy Shevchenko Signed-off-by: Feng Jiang --- lib/tests/string_kunit.c | 50 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 49 insertions(+), 1 deletion(-) diff --git a/lib/tests/string_kunit.c b/lib/tests/string_kunit.c index e8d527336030..89b583cec2c8 100644 --- a/lib/tests/string_kunit.c +++ b/lib/tests/string_kunit.c @@ -21,7 +21,7 @@ #define STRING_TEST_MAX_OFFSET 16 =20 #if defined(__HAVE_ARCH_STRLEN) || defined(__HAVE_ARCH_STRNLEN) || \ - defined(__HAVE_ARCH_STRCHR) + defined(__HAVE_ARCH_STRCHR) || defined(__HAVE_ARCH_STRRCHR) #define STRING_BENCH_ENABLED #endif =20 @@ -444,6 +444,51 @@ static void string_test_strnchr(struct kunit *test) KUNIT_ASSERT_NULL(test, result); } =20 +#ifdef __HAVE_ARCH_STRRCHR +static void string_test_strrchr_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); + if (bench_cases[i].len > 0) + buf[bench_cases[i].len - 1] =3D 'A'; + 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)strrchr(buf, 'A'); + } + 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_strrchr(buf, 'A'); + } + end =3D ktime_get(); + time_generic =3D ktime_to_ns(ktime_sub(end, start)); + + string_bench_report(test, "strrchr", &bench_cases[i], + time_arch, time_generic); + } +} +#endif + static void string_test_strspn(struct kunit *test) { static const struct strspn_test { @@ -916,6 +961,9 @@ static struct kunit_case string_test_cases[] =3D { #endif KUNIT_CASE(string_test_strnchr), KUNIT_CASE(string_test_strrchr), +#ifdef __HAVE_ARCH_STRRCHR + KUNIT_CASE(string_test_strrchr_bench), +#endif KUNIT_CASE(string_test_strspn), KUNIT_CASE(string_test_strcmp), KUNIT_CASE(string_test_strcmp_long_strings), --=20 2.25.1