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

["Stanisław Kardach" <kda@semihalf.com>]

Hi Vladimir,

On Wed, Jun 1, 2022 at 11:41 AM Medvedkin, Vladimir
<vladimir.medvedkin@intel.com> wrote:
>
> 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!
Thanks for catching this. I'll send a followup right away.
>
> > +#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