From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id E32A0471AF; Thu, 8 Jan 2026 00:53:10 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 9F1DB4028C; Thu, 8 Jan 2026 00:53:10 +0100 (CET) Received: from mail-qv1-f45.google.com (mail-qv1-f45.google.com [209.85.219.45]) by mails.dpdk.org (Postfix) with ESMTP id 858B940261 for ; Thu, 8 Jan 2026 00:53:08 +0100 (CET) Received: by mail-qv1-f45.google.com with SMTP id 6a1803df08f44-88fe44cce7eso20888776d6.3 for ; Wed, 07 Jan 2026 15:53:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1767829988; x=1768434788; darn=dpdk.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=6C6F4W8rgSNlGB1q3tZQpAVO9O208HeEcS0vn3oKlsg=; b=W/Jjkqypqk/jcTHNp9H59H3/y/yxc8zQ5ZtwK59N/AzwtaTeGxCXTfwxqYITaZT2/p Q+XComqETkGos4T+Na5tPN/2ZNLcRsdnDDzjTqMIp5Wzh8qT+gmDLgzEcm8lp8dz5//f nVBMUYm6l2zTd/j5oOLkQ9ZxV7n6aM6MBBZ74n/dJo14hJDr9/QZBbnWsFrRjyBK5glX 3JXwRlNNyrkH8FNaTQUndOQiaZgViU5KmzJ0y10o9d1/appevgbpy8YS7bcC+D0+WOxZ 5MI6KskS7BoEABcAceEnSh71OyPd1uirUzF6ZPXuIiDuNrnFF005xHZn5K4+GOKpaDN0 UqTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767829988; x=1768434788; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=6C6F4W8rgSNlGB1q3tZQpAVO9O208HeEcS0vn3oKlsg=; b=ZJbdEFNANpPk7qxMiEA6Nta3nzqSNQupuu3OAQ9VpNp9K5Se/2RyEI7nKl8kf+Ee2M umdUW4HpU6YQMwhk//bTc1RyYtbvBahfQyOYK7hV/E6ONDQXapswzSrm2GAxLdckSjFQ MBqp4iqVsPsm/Db81Zh79ZD6kM1PXIWTnj7HegzgpNTk7D3wudKOO5OVAv3jazbPrCvF vsoGqXFgF5JdHPbwmBtUvWRU5Cm6wrParx4++8oKT3ALZ+I9NWuXAs/yCnZZ9DwxgQA5 exurQSz8CTeB0AUR6yD5naTKqzeB/nSmCADM9p5YaFLleRmlYfzuUDEWxEi8FfCxt6OD fdMw== X-Gm-Message-State: AOJu0YyBsj14b3DnyMzpThM36ufyWP3qFporK2yTEcgXaFodAw0tnXs0 W+aUaFs/6j59vp59iOD+4eC+pQ1clylfec7jtXQYHOgHnnheOPUZQ7G7w0Dfsg== X-Gm-Gg: AY/fxX4rvjBI4V8I51UbyW1r1eZMKTphL79swjKKeiVGU6AMo+3mF9cnsn1wucwi+Ya SwGGSsoF2WBkt70Rsmb9+eri0kSUCtvc9UQc+ns4FwMpm2vGMvmJlRLnCvaQXRkVNL1aVlFUovr arsSi2b6rtEb0SuNZdvWhxROPLr+YkEQJn3Z2tg0NGlyhCwCGUKVBw7kmqnYILwSzJP520s51sp eMbOPKJySVZEn1ed2mmvLSYF2Vsmi6+TzN5yweN0g5SFBn2nYmB0G6ZJ06bSCUNNKvvdKccyxM/ pApgUBLvbFD+PLPC6UaS5r5S/w3IMWcefF81wZjQaQrhwWbG1GGt+AEB0tcycAUv+bp71EmyMyx Pw1jfeShC51hJoLyZuxFZYBp0G9J2bUdL8FfoRQp7JHHonzpuS2qWet9otQ82rHf427Um1tSSJi nawMjnbmdbZItxqviyVZMJoBAAtnZkoLR9QUVsIsWjTLABqyMcnM0XW/KV14rKEPgfpOvz X-Google-Smtp-Source: AGHT+IFXtspv/4g+zQVnAADbQdL6h2aqYza8gZpwAtKgr8S+dSqSSDvhwIvpmgD3Hp5+7uer4wngYw== X-Received: by 2002:a05:6214:248a:b0:88a:52a1:257b with SMTP id 6a1803df08f44-890842cbc82mr65836446d6.59.1767829987563; Wed, 07 Jan 2026 15:53:07 -0800 (PST) Received: from st47p01nt-relayp03.apple.com ([2601:182:b80:6a50:75d8:5eda:abb3:12c5]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8907723436fsm47806646d6.34.2026.01.07.15.53.06 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 07 Jan 2026 15:53:07 -0800 (PST) From: Scott X-Google-Original-From: Scott To: dev@dpdk.org Cc: mb@smartsharesystems.com, Scott Mitchell Subject: [PATCH v4] net: optimize raw checksum computation Date: Wed, 7 Jan 2026 18:53:04 -0500 Message-Id: <20260107235304.30028-1-scott_mitchell@apple.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org From: Scott Mitchell __rte_raw_cksum uses a loop with memcpy on each iteration. GCC 15+ is able to vectorize the loop but Clang 18.1 is not. Replacing the memcpy with unaligned_uint16_t pointer access enables both GCC and Clang to vectorize with SSE/AVX/AVX-512. Performance results from cksum_perf_autotest on Intel Xeon (Cascade Lake, AVX-512) built with Clang 18.1 (TSC cycles/byte): Block size Before After Improvement 100 0.40 0.24 ~40% 1500 0.50 0.06 ~8x 9000 0.49 0.06 ~8x Signed-off-by: Scott Mitchell --- Changes in v4: - Replaced manual 64-byte loop unrolling with simple pointer iteration - Removed __rte_no_ubsan_alignment macro (no longer needed) - Removed rte_ip6.h false-positive warning fix (unable to repro locally) - Updated performance numbers: AVX-512 vectorization on Clang achieves ~8x improvement for large packets vs scalar implementation Changes in v3: - Added __rte_no_ubsan_alignment macro to suppress false-positive UBSAN alignment warnings when using unaligned_uint16_t - Fixed false-positive GCC maybe-uninitialized warning in rte_ip6.h exposed by optimization (can be split to separate patch once verified on CI) Changes in v2: - Fixed UndefinedBehaviorSanitizer errors by adding uint32_t casts to prevent signed integer overflow in addition chains - Restored uint32_t sum accumulator instead of uint64_t - Added 64k length to test_cksum_perf.c app/test/meson.build | 1 + app/test/test_cksum_fuzz.c | 241 +++++++++++++++++++++++++++++++++++++ app/test/test_cksum_perf.c | 2 +- lib/net/rte_cksum.h | 19 ++- 4 files changed, 252 insertions(+), 11 deletions(-) create mode 100644 app/test/test_cksum_fuzz.c diff --git a/app/test/meson.build b/app/test/meson.build index efec42a6bf..c92325ad58 100644 --- a/app/test/meson.build +++ b/app/test/meson.build @@ -38,6 +38,7 @@ source_file_deps = { 'test_byteorder.c': [], 'test_cfgfile.c': ['cfgfile'], 'test_cksum.c': ['net'], + 'test_cksum_fuzz.c': ['net'], 'test_cksum_perf.c': ['net'], 'test_cmdline.c': [], 'test_cmdline_cirbuf.c': [], diff --git a/app/test/test_cksum_fuzz.c b/app/test/test_cksum_fuzz.c new file mode 100644 index 0000000000..cc3c3e71e1 --- /dev/null +++ b/app/test/test_cksum_fuzz.c @@ -0,0 +1,241 @@ +/* SPDX-License-Identifier: BSD-3-Clause + * Copyright(c) 2026 Apple Inc. + */ + +#include +#include + +#include +#include +#include +#include +#include +#include + +#include "test.h" + +/* + * Fuzz test for __rte_raw_cksum optimization. + * Compares the optimized implementation against the original reference + * implementation across random data of various lengths. + */ + +#define DEFAULT_ITERATIONS 1000 +#define MAX_TEST_LEN 65536 /* 64K to match GRO frame sizes */ + +/* + * Original (reference) implementation of __rte_raw_cksum from DPDK v23.11. + * This is retained here for comparison testing against the optimized version. + */ +static inline uint32_t +__rte_raw_cksum_reference(const void *buf, size_t len, uint32_t sum) +{ + const void *end; + + for (end = RTE_PTR_ADD(buf, RTE_ALIGN_FLOOR(len, sizeof(uint16_t))); + buf != end; buf = RTE_PTR_ADD(buf, sizeof(uint16_t))) { + uint16_t v; + + memcpy(&v, buf, sizeof(uint16_t)); + sum += v; + } + + /* if length is odd, keeping it byte order independent */ + if (unlikely(len % 2)) { + uint16_t left = 0; + + memcpy(&left, end, 1); + sum += left; + } + + return sum; +} + +static void +init_random_buffer(uint8_t *buf, size_t len) +{ + size_t i; + + for (i = 0; i < len; i++) + buf[i] = (uint8_t)rte_rand(); +} + +static inline uint32_t +get_initial_sum(bool random_initial_sum) +{ + return random_initial_sum ? (rte_rand() & 0xFFFFFFFF) : 0; +} + +/* + * Test a single buffer length with specific alignment and initial sum + */ +static int +test_cksum_fuzz_length_aligned(size_t len, bool aligned, uint32_t initial_sum) +{ + uint8_t *data; + uint8_t *buf; + size_t alloc_size; + uint32_t sum_ref, sum_opt; + + if (len == 0 && !aligned) { + /* Skip unaligned test for zero length - nothing to test */ + return TEST_SUCCESS; + } + + /* Allocate exact size for aligned, +1 for unaligned offset */ + alloc_size = aligned ? len : len + 1; + if (alloc_size == 0) + alloc_size = 1; /* rte_malloc doesn't like 0 */ + + data = rte_malloc(NULL, alloc_size, 64); + if (data == NULL) { + printf("Failed to allocate %zu bytes\n", alloc_size); + return TEST_FAILED; + } + + buf = aligned ? data : (data + 1); + + init_random_buffer(buf, len); + + sum_ref = __rte_raw_cksum_reference(buf, len, initial_sum); + sum_opt = __rte_raw_cksum(buf, len, initial_sum); + + if (sum_ref != sum_opt) { + printf("MISMATCH at len=%zu aligned='%s' initial_sum=0x%08x ref=0x%08x opt=0x%08x\n", + len, aligned ? "aligned" : "unaligned", + initial_sum, sum_ref, sum_opt); + rte_hexdump(stdout, "failing buffer", buf, len); + rte_free(data); + return TEST_FAILED; + } + + rte_free(data); + return TEST_SUCCESS; +} + +/* + * Test a length with both alignments + */ +static int +test_cksum_fuzz_length(size_t len, uint32_t initial_sum) +{ + int rc; + + /* Test aligned */ + rc = test_cksum_fuzz_length_aligned(len, true, initial_sum); + if (rc != TEST_SUCCESS) + return rc; + + /* Test unaligned */ + rc = test_cksum_fuzz_length_aligned(len, false, initial_sum); + + return rc; +} + +/* + * Test specific edge case lengths + */ +static int +test_cksum_fuzz_edge_cases(void) +{ + /* Edge case lengths that might trigger bugs */ + static const size_t edge_lengths[] = { + 0, 1, 2, 3, 4, 5, 6, 7, 8, + 15, 16, 17, + 31, 32, 33, + 63, 64, 65, + 127, 128, 129, + 255, 256, 257, + 511, 512, 513, + 1023, 1024, 1025, + 1500, 1501, /* MTU boundaries */ + 2047, 2048, 2049, + 4095, 4096, 4097, + 8191, 8192, 8193, + 16383, 16384, 16385, + 32767, 32768, 32769, + 65534, 65535, 65536 /* 64K GRO boundaries */ + }; + unsigned int i; + int rc; + + printf("Testing edge case lengths...\n"); + + for (i = 0; i < RTE_DIM(edge_lengths); i++) { + /* Test with zero initial sum */ + rc = test_cksum_fuzz_length(edge_lengths[i], 0); + if (rc != TEST_SUCCESS) + return rc; + + /* Test with random initial sum */ + rc = test_cksum_fuzz_length(edge_lengths[i], get_initial_sum(true)); + if (rc != TEST_SUCCESS) + return rc; + } + + return TEST_SUCCESS; +} + +/* + * Test random lengths with optional random initial sums + */ +static int +test_cksum_fuzz_random(unsigned int iterations, bool random_initial_sum) +{ + unsigned int i; + int rc; + + printf("Testing random lengths (0-%d)%s...\n", MAX_TEST_LEN, + random_initial_sum ? " with random initial sums" : ""); + + for (i = 0; i < iterations; i++) { + size_t len = rte_rand() % (MAX_TEST_LEN + 1); + + rc = test_cksum_fuzz_length(len, get_initial_sum(random_initial_sum)); + if (rc != TEST_SUCCESS) { + printf("Failed at len=%zu\n", len); + return rc; + } + } + + return TEST_SUCCESS; +} + +static int +test_cksum_fuzz(void) +{ + int rc; + unsigned int iterations = DEFAULT_ITERATIONS; + + printf("### __rte_raw_cksum optimization fuzz test ###\n"); + printf("Iterations per test: %u\n\n", iterations); + + /* Test edge cases */ + rc = test_cksum_fuzz_edge_cases(); + if (rc != TEST_SUCCESS) { + printf("Edge case test FAILED\n"); + return rc; + } + printf("Edge case test PASSED\n\n"); + + /* Test random lengths with zero initial sum */ + rc = test_cksum_fuzz_random(iterations, false); + if (rc != TEST_SUCCESS) { + printf("Random length test FAILED\n"); + return rc; + } + printf("Random length test PASSED\n\n"); + + /* Test random lengths with random initial sums */ + rc = test_cksum_fuzz_random(iterations, true); + if (rc != TEST_SUCCESS) { + printf("Random initial sum test FAILED\n"); + return rc; + } + printf("Random initial sum test PASSED\n\n"); + + printf("All fuzz tests PASSED!\n"); + return TEST_SUCCESS; +} + +REGISTER_FAST_TEST(cksum_fuzz_autotest, true, true, test_cksum_fuzz); diff --git a/app/test/test_cksum_perf.c b/app/test/test_cksum_perf.c index 0b919cd59f..6b1d4589e0 100644 --- a/app/test/test_cksum_perf.c +++ b/app/test/test_cksum_perf.c @@ -15,7 +15,7 @@ #define NUM_BLOCKS 10 #define ITERATIONS 1000000 -static const size_t data_sizes[] = { 20, 21, 100, 101, 1500, 1501 }; +static const size_t data_sizes[] = { 20, 21, 100, 101, 1500, 1501, 9000, 9001, 65536, 65537 }; static __rte_noinline uint16_t do_rte_raw_cksum(const void *buf, size_t len) diff --git a/lib/net/rte_cksum.h b/lib/net/rte_cksum.h index a8e8927952..a582e3a158 100644 --- a/lib/net/rte_cksum.h +++ b/lib/net/rte_cksum.h @@ -42,20 +42,19 @@ extern "C" { static inline uint32_t __rte_raw_cksum(const void *buf, size_t len, uint32_t sum) { - const void *end; + /* + * Process as uint16 chunks to preserve overflow/carry math. + * GCC and Clang vectorize the loop (if SSE available). + */ + const void *end = RTE_PTR_ADD(buf, RTE_ALIGN_FLOOR(len, sizeof(uint16_t))); - for (end = RTE_PTR_ADD(buf, RTE_ALIGN_FLOOR(len, sizeof(uint16_t))); - buf != end; buf = RTE_PTR_ADD(buf, sizeof(uint16_t))) { - uint16_t v; - - memcpy(&v, buf, sizeof(uint16_t)); - sum += v; - } + for (const unaligned_uint16_t *buf16 = (const unaligned_uint16_t *)buf; + buf16 != end; buf16++) + sum += *buf16; /* if length is odd, keeping it byte order independent */ - if (unlikely(len % 2)) { + if (len & 1) { uint16_t left = 0; - memcpy(&left, end, 1); sum += left; } -- 2.39.5 (Apple Git-154)