> When choosing a vector path to take, an extra condition must be
> satisfied to ensure the max SIMD bitwidth allows for the CPU enabled
> path.
>
> The vector path was initially chosen in RTE_INIT, however this is no
> longer suitable as we cannot check the max SIMD bitwidth at that time.
> Default handlers are now chosen in RTE_INIT, these default handlers
> are used the first time the crc calc is called, and they set the suitable
> handlers to be used going forward.
>
> Suggested-by: Jasvinder Singh <jasvinder.si...@intel.com>
> Suggested-by: Olivier Matz <olivier.m...@6wind.com>
>
> Signed-off-by: Ciara Power <ciara.po...@intel.com>
>
> ---
> v4:
> - Added default handlers to be set at RTE_INIT time, rather than
> choosing scalar handlers.
> - Modified logging.
> - Updated enum name.
> v3:
> - Moved choosing vector paths out of RTE_INIT.
> - Moved checking max_simd_bitwidth into the set_alg function.
> ---
> lib/librte_net/rte_net_crc.c | 75 ++++++++++++++++++++++++++++++------
> lib/librte_net/rte_net_crc.h | 8 ++++
> 2 files changed, 72 insertions(+), 11 deletions(-)
>
> diff --git a/lib/librte_net/rte_net_crc.c b/lib/librte_net/rte_net_crc.c
> index 4f5b9e8286..11d0161a32 100644
> --- a/lib/librte_net/rte_net_crc.c
> +++ b/lib/librte_net/rte_net_crc.c
> @@ -9,6 +9,7 @@
> #include <rte_cpuflags.h>
> #include <rte_common.h>
> #include <rte_net_crc.h>
> +#include <rte_eal.h>
>
> #if defined(RTE_ARCH_X86_64) && defined(__PCLMUL__)
> #define X86_64_SSE42_PCLMULQDQ 1
> @@ -32,6 +33,12 @@
> static uint32_t crc32_eth_lut[CRC_LUT_SIZE];
> static uint32_t crc16_ccitt_lut[CRC_LUT_SIZE];
>
> +static uint32_t
> +rte_crc16_ccitt_default_handler(const uint8_t *data, uint32_t data_len);
> +
> +static uint32_t
> +rte_crc32_eth_default_handler(const uint8_t *data, uint32_t data_len);
> +
> static uint32_t
> rte_crc16_ccitt_handler(const uint8_t *data, uint32_t data_len);
>
> @@ -41,7 +48,12 @@ rte_crc32_eth_handler(const uint8_t *data, uint32_t
> data_len);
> typedef uint32_t
> (*rte_net_crc_handler)(const uint8_t *data, uint32_t data_len);
>
> -static rte_net_crc_handler *handlers;
> +static rte_net_crc_handler handlers_default[] = {
> + [RTE_NET_CRC16_CCITT] = rte_crc16_ccitt_default_handler,
> + [RTE_NET_CRC32_ETH] = rte_crc32_eth_default_handler,
> +};
> +
> +static rte_net_crc_handler *handlers = handlers_default;
>
> static rte_net_crc_handler handlers_scalar[] = {
> [RTE_NET_CRC16_CCITT] = rte_crc16_ccitt_handler,
> @@ -60,6 +72,9 @@ static rte_net_crc_handler handlers_neon[] = {
> };
> #endif
>
> +static uint16_t max_simd_bitwidth;
> +RTE_LOG_REGISTER(libnet_logtype, lib.net, INFO);
> +
> /**
> * Reflect the bits about the middle
> *
> @@ -112,6 +127,42 @@ crc32_eth_calc_lut(const uint8_t *data,
> return crc;
> }
>
> +static uint32_t
> +rte_crc16_ccitt_default_handler(const uint8_t *data, uint32_t data_len)
> +{
> + if (max_simd_bitwidth == 0)
> + max_simd_bitwidth = rte_get_max_simd_bitwidth();
> + handlers = handlers_scalar;
> +#ifdef X86_64_SSE42_PCLMULQDQ
> + if (max_simd_bitwidth >= RTE_SIMD_128)
> + handlers = handlers_sse42;
> +#endif
> +#ifdef ARM64_NEON_PMULL
> + if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_PMULL) &&
> + max_simd_bitwidth >= RTE_SIMD_128) {
> + handlers = handlers_neon;
> +#endif
You probably don't want to make all these checks for *every* invocation
of that function. I think it would be better:
if (ma_simd_bitwidth == 0) {....}
return handlers[..](...);
BTW, while it allows us to use best possible handler,
such approach means extra indirect call(/jump) anyway.
Hard to say off-hand would it affect performance,
and if yes how significantly.
Couldn't find any perf tests in our UT for it...
> + return handlers[RTE_NET_CRC16_CCITT](data, data_len);
> +}
> +
> +static uint32_t
> +rte_crc32_eth_default_handler(const uint8_t *data, uint32_t data_len)
> +{
> + if (max_simd_bitwidth == 0)
> + max_simd_bitwidth = rte_get_max_simd_bitwidth();
> + handlers = handlers_scalar;
> +#ifdef X86_64_SSE42_PCLMULQDQ
> + if (max_simd_bitwidth >= RTE_SIMD_128)
> + handlers = handlers_sse42;
> +#endif
> +#ifdef ARM64_NEON_PMULL
> + if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_PMULL) &&
> + max_simd_bitwidth >= RTE_SIMD_128) {
> + handlers = handlers_neon;
> +#endif
> + return handlers[RTE_NET_CRC32_ETH](data, data_len);
> +}
> +
> static void
> rte_net_crc_scalar_init(void)
> {
> @@ -145,18 +196,26 @@ rte_crc32_eth_handler(const uint8_t *data, uint32_t
> data_len)
> void
> rte_net_crc_set_alg(enum rte_net_crc_alg alg)
> {
> + if (max_simd_bitwidth == 0)
> + max_simd_bitwidth = rte_get_max_simd_bitwidth();
> +
> switch (alg) {
> #ifdef X86_64_SSE42_PCLMULQDQ
> case RTE_NET_CRC_SSE42:
> - handlers = handlers_sse42;
> - break;
> + if (max_simd_bitwidth >= RTE_SIMD_128) {
> + handlers = handlers_sse42;
> + return;
> + }
> + NET_LOG(INFO, "Max SIMD Bitwidth too low, can't use SSE\n");
> #elif defined ARM64_NEON_PMULL
> /* fall-through */
> case RTE_NET_CRC_NEON:
> - if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_PMULL)) {
> + if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_PMULL) &&
> + max_simd_bitwidth >= RTE_SIMD_128) {
> handlers = handlers_neon;
> - break;
> + return;
> }
> + NET_LOG(INFO, "Max SIMD Bitwidth too low or CPU flag not
> enabled, can't use NEON\n");
> #endif
> /* fall-through */
> case RTE_NET_CRC_SCALAR:
> @@ -184,19 +243,13 @@ rte_net_crc_calc(const void *data,
> /* Select highest available crc algorithm as default one */
> RTE_INIT(rte_net_crc_init)
> {
> - enum rte_net_crc_alg alg = RTE_NET_CRC_SCALAR;
> -
> rte_net_crc_scalar_init();
>
> #ifdef X86_64_SSE42_PCLMULQDQ
> - alg = RTE_NET_CRC_SSE42;
> rte_net_crc_sse42_init();
> #elif defined ARM64_NEON_PMULL
> if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_PMULL)) {
> - alg = RTE_NET_CRC_NEON;
> rte_net_crc_neon_init();
> }
> #endif
> -
> - rte_net_crc_set_alg(alg);
> }
> diff --git a/lib/librte_net/rte_net_crc.h b/lib/librte_net/rte_net_crc.h
> index 16e85ca970..c942865ecf 100644
> --- a/lib/librte_net/rte_net_crc.h
> +++ b/lib/librte_net/rte_net_crc.h
> @@ -7,6 +7,8 @@
>
> #include <stdint.h>
>
> +#include <rte_log.h>
> +
> #ifdef __cplusplus
> extern "C" {
> #endif
> @@ -25,6 +27,12 @@ enum rte_net_crc_alg {
> RTE_NET_CRC_NEON,
> };
>
> +extern int libnet_logtype;
> +
> +#define NET_LOG(level, fmt, args...) \
> + rte_log(RTE_LOG_ ## level, libnet_logtype, "%s(): " fmt "\n", \
> + __func__, ## args)
> +
> /**
> * This API set the CRC computation algorithm (i.e. scalar version,
> * x86 64-bit sse4.2 intrinsic version, etc.) and internal data
> --
> 2.22.0
