Patch file metadata format has extra delineator which makes diff in patches.dpdk incorrect. I will resubmit v9. I apologize for the iterative approach.
On Thu, Jan 8, 2026 at 4:26 PM <[email protected]> wrote: > > From: Scott Mitchell <[email protected]> > > __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 <[email protected]> > --- > Changes in v8: > - __rte_raw_cksum: use native pointer arithmetic instead of RTE_PTR_ADD > to avoid incorrect results with -O3 for UDP checksums. Also improves > performance due to less assembly generated with Clang. > - Added __rte_no_ubsan_alignment attribute to suppress false UBSAN warnings > - Added RTE_SUPPRESS_UNINITIALIZED_WARNING macro for GCC workaround > - Fixed C++ compilation errors in rte_ip4.h and rte_ip6.h > - Formatted complex ternary expressions for readability > > Changes in v7: > - Replaced pointer arithmetic with RTE_PTR_ADD/RTE_ALIGN_FLOOR for DPDK > consistency > (BROKEN - Clang alias analysis bug causes incorrect UDP checksums) > > Changes in v6: > - Fixed GCC -Wmaybe-uninitialized false positive in mlx5 driver > > Changes in v5: > - Replaced memcpy loop with direct pointer access to enable vectorization > - Fixed GCC -Wmaybe-uninitialized false-positive warnings in > rte_ipv4_phdr_cksum > and rte_ipv6_phdr_cksum using compiler barriers (no assembly impact) > - Refactored hinic driver's local phdr_cksum implementations to call common > functions, eliminating duplication > - Simplified phdr_cksum struct initialization with designated initializers > > 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 | 240 +++++++++++++++++++++++++++++++ > app/test/test_cksum_perf.c | 2 +- > drivers/net/hinic/hinic_pmd_tx.c | 38 +---- > drivers/net/mlx5/mlx5_flow_dv.c | 2 + > lib/eal/include/rte_common.h | 22 +++ > lib/net/rte_cksum.h | 18 +-- > lib/net/rte_ip4.h | 26 ++-- > lib/net/rte_ip6.h | 17 ++- > 9 files changed, 294 insertions(+), 72 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..839861f57d > --- /dev/null > +++ b/app/test/test_cksum_fuzz.c > @@ -0,0 +1,240 @@ > +/* SPDX-License-Identifier: BSD-3-Clause > + * Copyright(c) 2026 Apple Inc. > + */ > + > +#include <stdio.h> > +#include <string.h> > + > +#include <rte_common.h> > +#include <rte_cycles.h> > +#include <rte_hexdump.h> > +#include <rte_cksum.h> > +#include <rte_malloc.h> > +#include <rte_random.h> > + > +#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/drivers/net/hinic/hinic_pmd_tx.c > b/drivers/net/hinic/hinic_pmd_tx.c > index 22fb0bffaf..6b36ad84fd 100644 > --- a/drivers/net/hinic/hinic_pmd_tx.c > +++ b/drivers/net/hinic/hinic_pmd_tx.c > @@ -706,47 +706,13 @@ hinic_get_sq_wqe(struct hinic_txq *txq, int wqebb_cnt, > static inline uint16_t > hinic_ipv4_phdr_cksum(const struct rte_ipv4_hdr *ipv4_hdr, uint64_t ol_flags) > { > - struct ipv4_psd_header { > - uint32_t src_addr; /* IP address of source host. */ > - uint32_t dst_addr; /* IP address of destination host. */ > - uint8_t zero; /* zero. */ > - uint8_t proto; /* L4 protocol type. */ > - uint16_t len; /* L4 length. */ > - } psd_hdr; > - > - psd_hdr.src_addr = ipv4_hdr->src_addr; > - psd_hdr.dst_addr = ipv4_hdr->dst_addr; > - psd_hdr.zero = 0; > - psd_hdr.proto = ipv4_hdr->next_proto_id; > - if (ol_flags & RTE_MBUF_F_TX_TCP_SEG) { > - psd_hdr.len = 0; > - } else { > - psd_hdr.len = > - rte_cpu_to_be_16(rte_be_to_cpu_16(ipv4_hdr->total_length) - > - rte_ipv4_hdr_len(ipv4_hdr)); > - } > - return rte_raw_cksum(&psd_hdr, sizeof(psd_hdr)); > + return rte_ipv4_phdr_cksum(ipv4_hdr, ol_flags & > RTE_MBUF_F_TX_TCP_SEG); > } > > static inline uint16_t > hinic_ipv6_phdr_cksum(const struct rte_ipv6_hdr *ipv6_hdr, uint64_t ol_flags) > { > - uint32_t sum; > - struct { > - uint32_t len; /* L4 length. */ > - uint32_t proto; /* L4 protocol - top 3 bytes must be zero */ > - } psd_hdr; > - > - psd_hdr.proto = (ipv6_hdr->proto << 24); > - if (ol_flags & RTE_MBUF_F_TX_TCP_SEG) > - psd_hdr.len = 0; > - else > - psd_hdr.len = ipv6_hdr->payload_len; > - > - sum = __rte_raw_cksum(&ipv6_hdr->src_addr, > - sizeof(ipv6_hdr->src_addr) + sizeof(ipv6_hdr->dst_addr), 0); > - sum = __rte_raw_cksum(&psd_hdr, sizeof(psd_hdr), sum); > - return __rte_raw_cksum_reduce(sum); > + return rte_ipv6_phdr_cksum(ipv6_hdr, ol_flags & > RTE_MBUF_F_TX_TCP_SEG); > } > > static inline void hinic_get_outer_cs_pld_offset(struct rte_mbuf *m, > diff --git a/drivers/net/mlx5/mlx5_flow_dv.c b/drivers/net/mlx5/mlx5_flow_dv.c > index 47f6d28410..4f77a1e4f1 100644 > --- a/drivers/net/mlx5/mlx5_flow_dv.c > +++ b/drivers/net/mlx5/mlx5_flow_dv.c > @@ -4445,6 +4445,8 @@ __flow_encap_decap_resource_register(struct rte_eth_dev > *dev, > .reserve = 0, > } > }; > + RTE_SUPPRESS_UNINITIALIZED_WARNING(encap_decap_key); > + > struct mlx5_flow_cb_ctx ctx = { > .error = error, > .data = resource, > diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h > index 9e7d84f929..044275c2bd 100644 > --- a/lib/eal/include/rte_common.h > +++ b/lib/eal/include/rte_common.h > @@ -546,6 +546,28 @@ static void __attribute__((destructor(RTE_PRIO(prio)), > used)) func(void) > #define __rte_no_asan > #endif > > +/** > + * Disable UndefinedBehaviorSanitizer alignment check on some code > + */ > +#if defined(RTE_CC_CLANG) || defined(RTE_CC_GCC) > +#define __rte_no_ubsan_alignment __attribute__((no_sanitize("alignment"))) > +#else > +#define __rte_no_ubsan_alignment > +#endif > + > +/** > + * Suppress GCC -Wmaybe-uninitialized false positive on struct > initialization. > + * This tells the compiler that the variable's memory has been touched, > + * preventing the false positive without affecting other optimizations. > + */ > +#ifdef RTE_CC_GCC > +#define RTE_SUPPRESS_UNINITIALIZED_WARNING(var) do { \ > + asm volatile("" : "+m" (var)); \ > +} while (0) > +#else > +#define RTE_SUPPRESS_UNINITIALIZED_WARNING(var) > +#endif > + > /*********** Macros for pointer arithmetic ********/ > > /** > diff --git a/lib/net/rte_cksum.h b/lib/net/rte_cksum.h > index a8e8927952..364f519455 100644 > --- a/lib/net/rte_cksum.h > +++ b/lib/net/rte_cksum.h > @@ -39,23 +39,19 @@ extern "C" { > * @return > * sum += Sum of all words in the buffer. > */ > +__rte_no_ubsan_alignment > static inline uint32_t > __rte_raw_cksum(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; > - } > + /* Process uint16 chunks to preserve overflow/carry math. GCC/Clang > vectorize the loop. */ > + const unaligned_uint16_t *buf16 = (const unaligned_uint16_t *)buf; > + const unaligned_uint16_t *end = buf16 + (len / sizeof(uint16_t)); > + for (; 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; > } > diff --git a/lib/net/rte_ip4.h b/lib/net/rte_ip4.h > index 822a660cfb..63852717c9 100644 > --- a/lib/net/rte_ip4.h > +++ b/lib/net/rte_ip4.h > @@ -223,21 +223,17 @@ rte_ipv4_phdr_cksum(const struct rte_ipv4_hdr > *ipv4_hdr, uint64_t ol_flags) > uint8_t zero; /* zero. */ > uint8_t proto; /* L4 protocol type. */ > uint16_t len; /* L4 length. */ > - } psd_hdr; > - > - uint32_t l3_len; > - > - psd_hdr.src_addr = ipv4_hdr->src_addr; > - psd_hdr.dst_addr = ipv4_hdr->dst_addr; > - psd_hdr.zero = 0; > - psd_hdr.proto = ipv4_hdr->next_proto_id; > - if (ol_flags & (RTE_MBUF_F_TX_TCP_SEG | RTE_MBUF_F_TX_UDP_SEG)) { > - psd_hdr.len = 0; > - } else { > - l3_len = rte_be_to_cpu_16(ipv4_hdr->total_length); > - psd_hdr.len = rte_cpu_to_be_16((uint16_t)(l3_len - > - rte_ipv4_hdr_len(ipv4_hdr))); > - } > + } psd_hdr = { > + .src_addr = ipv4_hdr->src_addr, > + .dst_addr = ipv4_hdr->dst_addr, > + .proto = ipv4_hdr->next_proto_id, > + .len = (ol_flags & (RTE_MBUF_F_TX_TCP_SEG | > RTE_MBUF_F_TX_UDP_SEG)) > + ? (uint16_t)0 > + : > rte_cpu_to_be_16((uint16_t)(rte_be_to_cpu_16(ipv4_hdr->total_length) - > + rte_ipv4_hdr_len(ipv4_hdr))) > + }; > + RTE_SUPPRESS_UNINITIALIZED_WARNING(psd_hdr); > + > return rte_raw_cksum(&psd_hdr, sizeof(psd_hdr)); > } > > diff --git a/lib/net/rte_ip6.h b/lib/net/rte_ip6.h > index d1abf1f5d5..8a7e5e4b8a 100644 > --- a/lib/net/rte_ip6.h > +++ b/lib/net/rte_ip6.h > @@ -560,19 +560,18 @@ rte_ipv6_phdr_cksum(const struct rte_ipv6_hdr > *ipv6_hdr, uint64_t ol_flags) > static inline uint16_t > rte_ipv6_phdr_cksum(const struct rte_ipv6_hdr *ipv6_hdr, uint64_t ol_flags) > { > - uint32_t sum; > struct { > rte_be32_t len; /* L4 length. */ > rte_be32_t proto; /* L4 protocol - top 3 bytes must be zero */ > - } psd_hdr; > - > - psd_hdr.proto = (uint32_t)(ipv6_hdr->proto << 24); > - if (ol_flags & (RTE_MBUF_F_TX_TCP_SEG | RTE_MBUF_F_TX_UDP_SEG)) > - psd_hdr.len = 0; > - else > - psd_hdr.len = ipv6_hdr->payload_len; > + } psd_hdr = { > + .len = (ol_flags & (RTE_MBUF_F_TX_TCP_SEG | > RTE_MBUF_F_TX_UDP_SEG)) > + ? (rte_be32_t)0 > + : ipv6_hdr->payload_len, > + .proto = (uint32_t)(ipv6_hdr->proto << 24) > + }; > + RTE_SUPPRESS_UNINITIALIZED_WARNING(psd_hdr); > > - sum = __rte_raw_cksum(&ipv6_hdr->src_addr, > + uint32_t sum = __rte_raw_cksum(&ipv6_hdr->src_addr, > sizeof(ipv6_hdr->src_addr) + sizeof(ipv6_hdr->dst_addr), > 0); > sum = __rte_raw_cksum(&psd_hdr, sizeof(psd_hdr), sum); > -- > 2.39.5 (Apple Git-154) >
