Hi Mairtin,
> -----Original Message-----
> From: O'loingsigh, Mairtin <mairtin.oloings...@intel.com>
> Sent: Tuesday, September 29, 2020 4:36 PM
> To: Singh, Jasvinder <jasvinder.si...@intel.com>; Richardson, Bruce
> <bruce.richard...@intel.com>; De Lara Guarch, Pablo
> <pablo.de.lara.gua...@intel.com>
> Cc: dev@dpdk.org; Ryan, Brendan <brendan.r...@intel.com>; Coyle, David
> <david.co...@intel.com>; O'loingsigh, Mairtin <mairtin.oloings...@intel.com>
> Subject: [PATCH v3 2/2] net: add support for AVX512/VPCLMULQDQ based CRC
>
> This patch enables the optimized calculation of CRC32-Ethernet and CRC16-
> CCITT using the AVX512 and VPCLMULQDQ instruction sets. This CRC
> implementation is built if the compiler supports the required instruction
> sets. It is
> selected at run-time if the host CPU, again, supports the required instruction
> sets.
>
> Signed-off-by: Mairtin o Loingsigh <mairtin.oloings...@intel.com>
> Signed-off-by: David Coyle <david.co...@intel.com>
...
> +static __rte_always_inline uint32_t
> +crc32_eth_calc_vpclmulqdq(const uint8_t *data, uint32_t data_len, uint32_t
> crc,
> + const struct crc_vpclmulqdq_ctx *params) {
> + __m128i res, d;
> + __m256i b;
> + __m512i temp, k;
> + __m512i qw0 = _mm512_set1_epi64(0), qw1, qw2, qw3;
> + __m512i fold0, fold1, fold2, fold3;
> + __mmask16 mask;
> + uint32_t n = 0;
> + int reduction = 0;
> +
> + /* Get CRC init value */
> + b = _mm256_insert_epi32(_mm256_setzero_si256(), crc, 0);
> + temp = _mm512_inserti32x8(_mm512_setzero_si512(), b, 0);
You can replace this with the following, which produces less instructions
(b needs to be changed to __m128i):
b = _mm_cvtsi32_si128(crc);
temp = _mm512_castsi128_si512(b);
> +
> + if (data_len > 255) {
> + fold0 = _mm512_loadu_si512((const __m512i *)data);
...
> + } else {
> + if (data_len > 31) {
> + res = _mm_insert_epi32(_mm_setzero_si128(), crc, 0);
Should work better with:
res = _mm_cvtsi32_si128(crc);
> + d = _mm_loadu_si128((const __m128i *)data);
> + res = _mm_xor_si128(res, d);
> + n += 16;
> +
> + reduction = 240 - ((n+256)-data_len);
> +
> + while (reduction > 0)
> + reduction_loop(&res, &reduction, data, &n,
> + params);
> +
> + if (n != data_len)
> + res = last_two_xmm(data, data_len, n, res,
> + params);
> + } else if (data_len > 16) {
> + res = _mm_insert_epi32(_mm_setzero_si128(), crc, 0);
Same as above.
> + d = _mm_loadu_si128((const __m128i *)data);
> + res = _mm_xor_si128(res, d);
> + n += 16;
> +
> + if (n != data_len)
> + res = last_two_xmm(data, data_len, n, res,
> + params);
> + } else if (data_len == 16) {
> + res = _mm_insert_epi32(_mm_setzero_si128(), crc, 0);
Same.
> + d = _mm_loadu_si128((const __m128i *)data);
> + res = _mm_xor_si128(res, d);
> + } else {
> + res = _mm_insert_epi32(_mm_setzero_si128(), crc, 0);
Same.
> + mask = byte_len_to_mask_table[data_len];
> + d = _mm_maskz_loadu_epi8(mask, data);
