Re: [PATCH 2/3] lib/lpm: R-V V rte_lpm_lookupx4

["Medvedkin, Vladimir" <vladimir.medvedkin@intel.com>]

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Hi Sunyuechi,


On 28/05/2025 18:00, uk7b@foxmail.com wrote:
> From: sunyuechi<sunyuechi@iscas.ac.cn>
>
> bpi-f3:
>      scalar: 5.7 cycles
>      rvv:    2.4 cycles
>
> Maybe runtime detection in LPM should be added for all architectures,
> but this commit is only about the RVV part.

Iwouldadviseyouto lookintothe FIBlibrary,ithasexactlywhatyouare lookingfor.

Also,pleaseconsiderwritinga slightlymoreinformativeandexplanatorycommit 
message.

> Signed-off-by: sunyuechi<sunyuechi@iscas.ac.cn>
> ---
>   MAINTAINERS           |  2 +
>   lib/lpm/meson.build   |  1 +
>   lib/lpm/rte_lpm.h     |  2 +
>   lib/lpm/rte_lpm_rvv.h | 91 +++++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 96 insertions(+)
>   create mode 100644 lib/lpm/rte_lpm_rvv.h
>
<snip>
> +static inline void rte_lpm_lookupx4_rvv(
> +	const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4], uint32_t defv)
> +{
> +	size_t vl = 4;
> +
> +	const uint32_t *tbl24_p = (const uint32_t *)lpm->tbl24;
> +	uint32_t tbl_entries[4] = {
> +		tbl24_p[((uint32_t)ip[0]) >> 8],
> +		tbl24_p[((uint32_t)ip[1]) >> 8],
> +		tbl24_p[((uint32_t)ip[2]) >> 8],
> +		tbl24_p[((uint32_t)ip[3]) >> 8],
> +	};

I'm notan expertinRISC-V,butwhyis itdonein a 
scalarwayinsteadofusing__riscv_vsrl_vx_u32m1()? Iassumeyou're 
relyingonthe compilerhere?

Also,have youredefinedthe xmm_t typeforproperindexaddressing?

> +	vuint32m1_t vtbl_entry = __riscv_vle32_v_u32m1(tbl_entries, vl);
> +
> +	vbool32_t mask = __riscv_vmseq_vx_u32m1_b32(
> +	    __riscv_vand_vx_u32m1(vtbl_entry, RTE_LPM_VALID_EXT_ENTRY_BITMASK, vl),
> +	    RTE_LPM_VALID_EXT_ENTRY_BITMASK, vl);
<snip>
> +
> +static inline void rte_lpm_lookupx4(
> +	const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4], uint32_t defv)
> +{
> +	lpm_lookupx4_impl(lpm, ip, hop, defv);
> +}
> +
> +RTE_INIT(rte_lpm_init_alg)
> +{
> +	lpm_lookupx4_impl = rte_cpu_get_flag_enabled(RTE_CPUFLAG_RISCV_ISA_V)
> +	    ? rte_lpm_lookupx4_rvv
> +	    : rte_lpm_lookupx4_scalar;
> +}
AsImentionedearlier,I'd recommendthat youuseFIBtoselectan 
implementationatruntime. All the rest LPM vector x4 implementations are 
done this way, and their code is inlined.
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* _RTE_LPM_RVV_H_ */

-- 
Regards,
Vladimir

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