From patchwork Tue Nov 30 14:22:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Hou Tao X-Patchwork-Id: 12647367 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47CB0C433FE for ; Tue, 30 Nov 2021 14:07:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233267AbhK3OKY (ORCPT ); Tue, 30 Nov 2021 09:10:24 -0500 Received: from szxga02-in.huawei.com ([45.249.212.188]:27320 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233178AbhK3OKU (ORCPT ); Tue, 30 Nov 2021 09:10:20 -0500 Received: from dggpeml500025.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4J3PCw13ytzbjBL; Tue, 30 Nov 2021 22:06:52 +0800 (CST) Received: from huawei.com (10.175.124.27) by dggpeml500025.china.huawei.com (7.185.36.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Tue, 30 Nov 2021 22:06:58 +0800 From: Hou Tao To: Alexei Starovoitov CC: Martin KaFai Lau , Yonghong Song , Daniel Borkmann , Andrii Nakryiko , , , Subject: [PATCH bpf-next 0/5] introduce bpf_strncmp() helper Date: Tue, 30 Nov 2021 22:22:10 +0800 Message-ID: <20211130142215.1237217-1-houtao1@huawei.com> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 X-Originating-IP: [10.175.124.27] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpeml500025.china.huawei.com (7.185.36.35) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Hi, The motivation for introducing bpf_strncmp() helper comes from two aspects: (1) clang doesn't always replace strncmp() automatically In tracing program, sometimes we need to using a home-made strncmp() to check whether or not the file name is expected. (2) the performance of home-made strncmp is not so good As shown in the benchmark in patch #4, the performance of bpf_strncmp() helper is 18% or 33% better than home-made strncmp() under x86-64 or arm64 when the compared string length is 64. When the string length grows to 4095, the performance win will be 179% or 600% under x86-64 or arm64. The prototype of bpf_strncmp() has changed from bpf_strncmp(const char *s1, const char *s2, u32 s2_sz) to bpf_strncmp(const char *s1, u32 s1_sz, const char *s2) The main reason is readability and there is nearly no performance difference between these two APIs (refer to the data attached below [1]). Any comments are welcome. Regards, Tao Change Log: v1: * change API to bpf_strncmp(const char *s1, u32 s1_sz, const char *s2) * add benchmark refactor and benchmark between bpf_strncmp() and strncmp() RFC: https://lore.kernel.org/bpf/20211106132822.1396621-1-houtao1@huawei.com/ [1] Performance difference between two APIs under x86-64: helper_rfc-X: use bpf_strncmp in RFC to compare X-sized string helper-Y: use bpf_strncmp in v1 to compare Y-sized string helper_rfc-1 3.482 ± 0.002M/s (drops 0.000 ± 0.000M/s) helper-1 3.485 ± 0.001M/s (drops 0.000 ± 0.000M/s) helper_rfc-8 3.428 ± 0.001M/s (drops 0.000 ± 0.000M/s) helper-8 3.434 ± 0.001M/s (drops 0.000 ± 0.000M/s) helper_rfc-32 3.253 ± 0.002M/s (drops 0.000 ± 0.000M/s) helper-32 3.234 ± 0.001M/s (drops 0.000 ± 0.000M/s) helper_rfc-64 3.039 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-64 3.042 ± 0.001M/s (drops 0.000 ± 0.000M/s) helper_rfc-128 2.640 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-128 2.633 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper_rfc-512 1.576 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-512 1.574 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper_rfc-2048 0.602 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-2048 0.602 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper_rfc-4095 0.328 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-4095 0.328 ± 0.000M/s (drops 0.000 ± 0.000M/s) Hou Tao (5): bpf: add bpf_strncmp helper selftests/bpf: fix checkpatch error on empty function parameter selftests/bpf: factor out common helpers for benchmarks selftests/bpf: add benchmark for bpf_strncmp() helper selftests/bpf: add test cases for bpf_strncmp() include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 11 ++ kernel/bpf/helpers.c | 16 ++ tools/include/uapi/linux/bpf.h | 11 ++ tools/testing/selftests/bpf/Makefile | 4 +- tools/testing/selftests/bpf/bench.c | 21 ++- tools/testing/selftests/bpf/bench.h | 34 +++- .../bpf/benchs/bench_bloom_filter_map.c | 44 ++--- .../selftests/bpf/benchs/bench_count.c | 16 +- .../selftests/bpf/benchs/bench_rename.c | 43 ++--- .../selftests/bpf/benchs/bench_ringbufs.c | 21 +-- .../selftests/bpf/benchs/bench_strncmp.c | 150 ++++++++++++++++ .../selftests/bpf/benchs/bench_trigger.c | 79 ++++---- .../selftests/bpf/benchs/run_bench_strncmp.sh | 12 ++ .../selftests/bpf/prog_tests/test_strncmp.c | 170 ++++++++++++++++++ .../selftests/bpf/progs/strncmp_bench.c | 50 ++++++ .../selftests/bpf/progs/strncmp_test.c | 59 ++++++ 17 files changed, 604 insertions(+), 138 deletions(-) create mode 100644 tools/testing/selftests/bpf/benchs/bench_strncmp.c create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh create mode 100644 tools/testing/selftests/bpf/prog_tests/test_strncmp.c create mode 100644 tools/testing/selftests/bpf/progs/strncmp_bench.c create mode 100644 tools/testing/selftests/bpf/progs/strncmp_test.c