Re: [PATCH v3 2/2] lpm: add a scalar version of lookupx4 function

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

Hi Stanislaw,


On 30/05/2022 19:24, Stanislaw Kardach wrote:
> From: Michal Mazurek <maz@semihalf.com>
> 
> Add an implementation of the rte_lpm_lookupx4() function for platforms
> without support for vector operations.
> 
> This will be useful in the upcoming RISC-V port as well as any platform
> which may want to start with a basic level of LPM support.
> 
> Signed-off-by: Michal Mazurek <maz@semihalf.com>
> Signed-off-by: Stanislaw Kardach <kda@semihalf.com>
> ---
>   doc/guides/rel_notes/release_22_07.rst |  5 ++++
>   lib/lpm/meson.build                    |  1 +
>   lib/lpm/rte_lpm.h                      |  4 ++-
>   lib/lpm/rte_lpm_scalar.h               | 40 ++++++++++++++++++++++++++
>   4 files changed, 49 insertions(+), 1 deletion(-)
>   create mode 100644 lib/lpm/rte_lpm_scalar.h
> 
> diff --git a/doc/guides/rel_notes/release_22_07.rst b/doc/guides/rel_notes/release_22_07.rst
> index e49cacecef..0cf3f71269 100644
> --- a/doc/guides/rel_notes/release_22_07.rst
> +++ b/doc/guides/rel_notes/release_22_07.rst
> @@ -104,6 +104,11 @@ New Features
>     * ``RTE_EVENT_QUEUE_ATTR_WEIGHT``
>     * ``RTE_EVENT_QUEUE_ATTR_AFFINITY``
>   
> +* **Added scalar version of the LPM library.**
> +
> +  * Added scalar implementation of ``rte_lpm_lookupx4``. This is a fall-back
> +    implementation for platforms that don't support vector operations.
> +
>   
>   Removed Items
>   -------------
> diff --git a/lib/lpm/meson.build b/lib/lpm/meson.build
> index 78d91d3421..6b47361fce 100644
> --- a/lib/lpm/meson.build
> +++ b/lib/lpm/meson.build
> @@ -14,6 +14,7 @@ headers = files('rte_lpm.h', 'rte_lpm6.h')
>   indirect_headers += files(
>           'rte_lpm_altivec.h',
>           'rte_lpm_neon.h',
> +        'rte_lpm_scalar.h',
>           'rte_lpm_sse.h',
>           'rte_lpm_sve.h',
>   )
> diff --git a/lib/lpm/rte_lpm.h b/lib/lpm/rte_lpm.h
> index 1cf863a146..4f38864fde 100644
> --- a/lib/lpm/rte_lpm.h
> +++ b/lib/lpm/rte_lpm.h
> @@ -405,8 +405,10 @@ rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4],
>   #endif
>   #elif defined(RTE_ARCH_PPC_64)
>   #include "rte_lpm_altivec.h"
> -#else
> +#elif defined(RTE_ARCH_X86)
>   #include "rte_lpm_sse.h"
> +#else
> +#include "rte_lpm_scalar.h"
>   #endif
>   
>   #ifdef __cplusplus
> diff --git a/lib/lpm/rte_lpm_scalar.h b/lib/lpm/rte_lpm_scalar.h
> new file mode 100644
> index 0000000000..4ae1b6f0b8
> --- /dev/null
> +++ b/lib/lpm/rte_lpm_scalar.h
> @@ -0,0 +1,40 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2022 StarFive
> + * Copyright(c) 2022 SiFive
> + * Copyright(c) 2022 Semihalf
> + */
> +
> +#ifndef _RTE_LPM_SCALAR_H_
> +#define _RTE_LPM_SCALAR_H_
> +
> +#include <rte_branch_prediction.h>
> +#include <rte_byteorder.h>
> +#include <rte_common.h>

Just a one nit, I think these 3 headers are not needed and can be 
removed. Apart from it looks good to me.
Thanks!

> +#include <rte_vect.h>
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +static inline void
> +rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4],
> +		uint32_t defv)
> +{
> +	uint32_t nh;
> +	int ret;
> +
> +	ret = rte_lpm_lookup(lpm, ((rte_xmm_t)ip).u32[0], &nh);
> +	hop[0] = (ret == 0) ? nh : defv;
> +	ret = rte_lpm_lookup(lpm, ((rte_xmm_t)ip).u32[1], &nh);
> +	hop[1] = (ret == 0) ? nh : defv;
> +	ret = rte_lpm_lookup(lpm, ((rte_xmm_t)ip).u32[2], &nh);
> +	hop[2] = (ret == 0) ? nh : defv;
> +	ret = rte_lpm_lookup(lpm, ((rte_xmm_t)ip).u32[3], &nh);
> +	hop[3] = (ret == 0) ? nh : defv;
> +}
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* _RTE_LPM_SCALAR_H_ */

Acked-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>

-- 
Regards,
Vladimir