On Fri, Jul 12, 2024 at 5:47 PM Daniel Gregory <daniel.greg...@bytedance.com> wrote: > > The RISC-V Zbc extension adds instructions for carry-less multiplication > we can use to implement CRC in hardware. This patch set contains two new > implementations: > > - one in lib/hash/rte_crc_riscv64.h that uses a Barrett reduction to > implement the four rte_hash_crc_* functions > - one in lib/net/net_crc_zbc.c that uses repeated single-folds to reduce > the buffer until it is small enough for a Barrett reduction to > implement rte_crc16_ccitt_zbc_handler and rte_crc32_eth_zbc_handler > > My approach is largely based on the Intel's "Fast CRC Computation Using > PCLMULQDQ Instruction" white paper > https://www.researchgate.net/publication/263424619_Fast_CRC_computation > and a post about "Optimizing CRC32 for small payload sizes on x86" > https://mary.rs/lab/crc32/ > > Whether these new implementations are enabled is controlled by new > build-time and run-time detection of the RISC-V extensions present in > the compiler and on the target system. > > I have carried out some performance comparisons between the generic > table implementations and the new hardware implementations. Listed below > is the number of cycles it takes to compute the CRC hash for buffers of > various sizes (as reported by rte_get_timer_cycles()). These results > were collected on a Kendryte K230 and averaged over 20 samples: > > |Buffer | CRC32-ETH (lib/net) | CRC32C (lib/hash) | > |Size (MB) | Table | Hardware | Table | Hardware | > |----------|----------|----------|----------|----------| > | 1 | 155168 | 11610 | 73026 | 18385 | > | 2 | 311203 | 22998 | 145586 | 35886 | > | 3 | 466744 | 34370 | 218536 | 53939 | > | 4 | 621843 | 45536 | 291574 | 71944 | > | 5 | 777908 | 56989 | 364152 | 89706 | > | 6 | 932736 | 68023 | 437016 | 107726 | > | 7 | 1088756 | 79236 | 510197 | 125426 | > | 8 | 1243794 | 90467 | 583231 | 143614 | > > These results suggest a speed-up of lib/net by thirteen times, and of > lib/hash by four times. > > I have also run the hash_functions_autotest benchmark in dpdk_test, > which measures the performance of the lib/hash implementation on small > buffers, getting the following times: > > | Key Length | Time (ticks/op) | > | (bytes) | Table | Hardware | > |------------|----------|----------| > | 1 | 0.47 | 0.85 | > | 2 | 0.57 | 0.87 | > | 4 | 0.99 | 0.88 | > | 8 | 1.35 | 0.88 | > | 9 | 1.20 | 1.09 | > | 13 | 1.76 | 1.35 | > | 16 | 1.87 | 1.02 | > | 32 | 2.96 | 0.98 | > | 37 | 3.35 | 1.45 | > | 40 | 3.49 | 1.12 | > | 48 | 4.02 | 1.25 | > | 64 | 5.08 | 1.54 |
Thanks for the submission. This series comes late for v24.07 and there was no review, it is deferred to v24.11. Cc: Sachin for info. -- David Marchand
