diff mbox series

[1/1] lpm: add a scalar version of lookupx4 function

Message ID 20220510115824.457885-1-kda@semihalf.com (mailing list archive)
State Superseded, archived
Delegated to: David Marchand
Headers
Series [1/1] lpm: add a scalar version of lookupx4 function |

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/github-robot: build success github build: passed
ci/iol-aarch64-compile-testing success Testing PASS
ci/iol-mellanox-Performance success Performance Testing PASS
ci/iol-aarch64-unit-testing success Testing PASS
ci/iol-intel-Functional success Functional Testing PASS
ci/iol-intel-Performance success Performance Testing PASS
ci/Intel-compilation success Compilation OK
ci/intel-Testing success Testing PASS

Commit Message

Stanislaw Kardach May 10, 2022, 11:58 a.m. UTC 
  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               | 122 +++++++++++++++++++++++++
 4 files changed, 131 insertions(+), 1 deletion(-)
 create mode 100644 lib/lpm/rte_lpm_scalar.h

Comments

Vladimir Medvedkin May 19, 2022, 5:02 p.m. UTC | #1 
Hi Stanislaw, Michal,

As far as I can see, this implementation almost completely repeats other 
lookupx4() implementations, except for the use of vector instructions.

On my board (x86_64) in lpm_perf_autotest your implementation takes about:
LPM LookupX4: 29.5 cycles (fails = 12.5%)

replacing this code with a simple loop with rte_lpm_lookup():

uint32_t nh;
int i, ret;

for (i = 0; i < 4; i++) {
   ret = rte_lpm_lookup((struct rte_lpm *)lpm, ((rte_xmm_t)ip).u32[i], &nh);
   hop[i] = (ret == 0) ? nh : defv;
}

works faster:
LPM LookupX4: 22.2 cycles (fails = 12.5%)

I'm wondering if this will work faster on your board (I assume it it 
RISC-V arch)?

Thanks!

On 10/05/2022 12:58, 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               | 122 +++++++++++++++++++++++++
>   4 files changed, 131 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 4ae91dd94d..73e8d632f2 100644
> --- a/doc/guides/rel_notes/release_22_07.rst
> +++ b/doc/guides/rel_notes/release_22_07.rst
> @@ -70,6 +70,11 @@ New Features
>     * Added AH mode support in lookaside protocol (IPsec) for CN9K & CN10K.
>     * Added AES-GMAC support in lookaside protocol (IPsec) for CN9K & CN10K.
>   
> +* **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 eb91960e81..b5db6a353a 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..991b94e687
> --- /dev/null
> +++ b/lib/lpm/rte_lpm_scalar.h
> @@ -0,0 +1,122 @@
> +/* 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>
> +#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)
> +{
> +	rte_xmm_t i24;
> +	rte_xmm_t i8;
> +	uint32_t tbl[4];
> +	uint64_t pt, pt2;
> +	const uint32_t *ptbl;
> +
> +	const rte_xmm_t mask8 = {
> +		.u32 = {UINT8_MAX, UINT8_MAX, UINT8_MAX, UINT8_MAX}};
> +
> +	/*
> +	 * RTE_LPM_VALID_EXT_ENTRY_BITMASK for 2 LPM entries
> +	 * as one 64-bit value (0x0300000003000000).
> +	 */
> +	const uint64_t mask_xv =
> +		((uint64_t)RTE_LPM_VALID_EXT_ENTRY_BITMASK |
> +		(uint64_t)RTE_LPM_VALID_EXT_ENTRY_BITMASK << 32);
> +
> +	/*
> +	 * RTE_LPM_LOOKUP_SUCCESS for 2 LPM entries
> +	 * as one 64-bit value (0x0100000001000000).
> +	 */
> +	const uint64_t mask_v =
> +		((uint64_t)RTE_LPM_LOOKUP_SUCCESS |
> +		(uint64_t)RTE_LPM_LOOKUP_SUCCESS << 32);
> +
> +	/* get 4 indexes for tbl24[]. */
> +	i24.x = ip;
> +	i24.u32[0] >>= CHAR_BIT;
> +	i24.u32[1] >>= CHAR_BIT;
> +	i24.u32[2] >>= CHAR_BIT;
> +	i24.u32[3] >>= CHAR_BIT;
> +
> +	/* extract values from tbl24[] */
> +	ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[0]];
> +	tbl[0] = *ptbl;
> +	ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[1]];
> +	tbl[1] = *ptbl;
> +	ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[2]];
> +	tbl[2] = *ptbl;
> +	ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[3]];
> +	tbl[3] = *ptbl;
> +
> +	/* get 4 indexes for tbl8[]. */
> +	i8.x = ip;
> +	i8.u64[0] &= mask8.u64[0];
> +	i8.u64[1] &= mask8.u64[1];
> +
> +	pt = (uint64_t)tbl[0] |
> +		(uint64_t)tbl[1] << 32;
> +	pt2 = (uint64_t)tbl[2] |
> +		(uint64_t)tbl[3] << 32;
> +
> +	/* search successfully finished for all 4 IP addresses. */
> +	if (likely((pt & mask_xv) == mask_v) &&
> +			likely((pt2 & mask_xv) == mask_v)) {
> +		*(uint64_t *)hop = pt & RTE_LPM_MASKX4_RES;
> +		*(uint64_t *)(hop + 2) = pt2 & RTE_LPM_MASKX4_RES;
> +		return;
> +	}
> +
> +	if (unlikely((pt & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
> +			RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
> +		i8.u32[0] = i8.u32[0] +
> +			(tbl[0] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
> +		ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[0]];
> +		tbl[0] = *ptbl;
> +	}
> +	if (unlikely((pt >> 32 & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
> +			RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
> +		i8.u32[1] = i8.u32[1] +
> +			(tbl[1] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
> +		ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[1]];
> +		tbl[1] = *ptbl;
> +	}
> +	if (unlikely((pt2 & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
> +			RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
> +		i8.u32[2] = i8.u32[2] +
> +			(tbl[2] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
> +		ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[2]];
> +		tbl[2] = *ptbl;
> +	}
> +	if (unlikely((pt2 >> 32 & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
> +			RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
> +		i8.u32[3] = i8.u32[3] +
> +			(tbl[3] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
> +		ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[3]];
> +		tbl[3] = *ptbl;
> +	}
> +
> +	hop[0] = (tbl[0] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[0] & 0x00FFFFFF : defv;
> +	hop[1] = (tbl[1] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[1] & 0x00FFFFFF : defv;
> +	hop[2] = (tbl[2] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[2] & 0x00FFFFFF : defv;
> +	hop[3] = (tbl[3] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[3] & 0x00FFFFFF : defv;
> +}
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* _RTE_LPM_SCALAR_H_ */
Stanislaw Kardach May 24, 2022, 4:28 p.m. UTC | #2 
On Thu, May 19, 2022 at 7:04 PM Medvedkin, Vladimir
<vladimir.medvedkin@intel.com> wrote:
>
> Hi Stanislaw, Michal,
>
> As far as I can see, this implementation almost completely repeats other
> lookupx4() implementations, except for the use of vector instructions.
>
> On my board (x86_64) in lpm_perf_autotest your implementation takes about:
> LPM LookupX4: 29.5 cycles (fails = 12.5%)
>
> replacing this code with a simple loop with rte_lpm_lookup():
>
> uint32_t nh;
> int i, ret;
>
> for (i = 0; i < 4; i++) {
>    ret = rte_lpm_lookup((struct rte_lpm *)lpm, ((rte_xmm_t)ip).u32[i], &nh);
>    hop[i] = (ret == 0) ? nh : defv;
> }
>
> works faster:
> LPM LookupX4: 22.2 cycles (fails = 12.5%)
>
> I'm wondering if this will work faster on your board (I assume it it
> RISC-V arch)?
Hi Vladimir,

On my HiFive Unmatched RISC-V board there is a marginal difference (~ -1.56%):
  Our version: 210.5 cycles (fails = 12.5%)
  rte_lpm_lookup version: 213.8 cycles (fails = 12.5%)
Given that x86 is faster with rte_lpm_lookup, I'll change to this
implementation in the next version.

That said I wonder why do we have different const requirements for
rte_lpm_lookup() and rte_lpm_lookupx4():
  static inline int rte_lpm_lookup(struct rte_lpm *lpm, uint32_t ip,
uint32_t *next_hop)
  static inline void rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t
ip, uint32_t hop[4], uint32_t defv);
I think both should be const.


>
> Thanks!
>
> On 10/05/2022 12:58, 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               | 122 +++++++++++++++++++++++++
> >   4 files changed, 131 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 4ae91dd94d..73e8d632f2 100644
> > --- a/doc/guides/rel_notes/release_22_07.rst
> > +++ b/doc/guides/rel_notes/release_22_07.rst
> > @@ -70,6 +70,11 @@ New Features
> >     * Added AH mode support in lookaside protocol (IPsec) for CN9K & CN10K.
> >     * Added AES-GMAC support in lookaside protocol (IPsec) for CN9K & CN10K.
> >
> > +* **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 eb91960e81..b5db6a353a 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..991b94e687
> > --- /dev/null
> > +++ b/lib/lpm/rte_lpm_scalar.h
> > @@ -0,0 +1,122 @@
> > +/* 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>
> > +#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)
> > +{
> > +     rte_xmm_t i24;
> > +     rte_xmm_t i8;
> > +     uint32_t tbl[4];
> > +     uint64_t pt, pt2;
> > +     const uint32_t *ptbl;
> > +
> > +     const rte_xmm_t mask8 = {
> > +             .u32 = {UINT8_MAX, UINT8_MAX, UINT8_MAX, UINT8_MAX}};
> > +
> > +     /*
> > +      * RTE_LPM_VALID_EXT_ENTRY_BITMASK for 2 LPM entries
> > +      * as one 64-bit value (0x0300000003000000).
> > +      */
> > +     const uint64_t mask_xv =
> > +             ((uint64_t)RTE_LPM_VALID_EXT_ENTRY_BITMASK |
> > +             (uint64_t)RTE_LPM_VALID_EXT_ENTRY_BITMASK << 32);
> > +
> > +     /*
> > +      * RTE_LPM_LOOKUP_SUCCESS for 2 LPM entries
> > +      * as one 64-bit value (0x0100000001000000).
> > +      */
> > +     const uint64_t mask_v =
> > +             ((uint64_t)RTE_LPM_LOOKUP_SUCCESS |
> > +             (uint64_t)RTE_LPM_LOOKUP_SUCCESS << 32);
> > +
> > +     /* get 4 indexes for tbl24[]. */
> > +     i24.x = ip;
> > +     i24.u32[0] >>= CHAR_BIT;
> > +     i24.u32[1] >>= CHAR_BIT;
> > +     i24.u32[2] >>= CHAR_BIT;
> > +     i24.u32[3] >>= CHAR_BIT;
> > +
> > +     /* extract values from tbl24[] */
> > +     ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[0]];
> > +     tbl[0] = *ptbl;
> > +     ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[1]];
> > +     tbl[1] = *ptbl;
> > +     ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[2]];
> > +     tbl[2] = *ptbl;
> > +     ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[3]];
> > +     tbl[3] = *ptbl;
> > +
> > +     /* get 4 indexes for tbl8[]. */
> > +     i8.x = ip;
> > +     i8.u64[0] &= mask8.u64[0];
> > +     i8.u64[1] &= mask8.u64[1];
> > +
> > +     pt = (uint64_t)tbl[0] |
> > +             (uint64_t)tbl[1] << 32;
> > +     pt2 = (uint64_t)tbl[2] |
> > +             (uint64_t)tbl[3] << 32;
> > +
> > +     /* search successfully finished for all 4 IP addresses. */
> > +     if (likely((pt & mask_xv) == mask_v) &&
> > +                     likely((pt2 & mask_xv) == mask_v)) {
> > +             *(uint64_t *)hop = pt & RTE_LPM_MASKX4_RES;
> > +             *(uint64_t *)(hop + 2) = pt2 & RTE_LPM_MASKX4_RES;
> > +             return;
> > +     }
> > +
> > +     if (unlikely((pt & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
> > +                     RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
> > +             i8.u32[0] = i8.u32[0] +
> > +                     (tbl[0] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
> > +             ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[0]];
> > +             tbl[0] = *ptbl;
> > +     }
> > +     if (unlikely((pt >> 32 & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
> > +                     RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
> > +             i8.u32[1] = i8.u32[1] +
> > +                     (tbl[1] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
> > +             ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[1]];
> > +             tbl[1] = *ptbl;
> > +     }
> > +     if (unlikely((pt2 & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
> > +                     RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
> > +             i8.u32[2] = i8.u32[2] +
> > +                     (tbl[2] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
> > +             ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[2]];
> > +             tbl[2] = *ptbl;
> > +     }
> > +     if (unlikely((pt2 >> 32 & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
> > +                     RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
> > +             i8.u32[3] = i8.u32[3] +
> > +                     (tbl[3] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
> > +             ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[3]];
> > +             tbl[3] = *ptbl;
> > +     }
> > +
> > +     hop[0] = (tbl[0] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[0] & 0x00FFFFFF : defv;
> > +     hop[1] = (tbl[1] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[1] & 0x00FFFFFF : defv;
> > +     hop[2] = (tbl[2] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[2] & 0x00FFFFFF : defv;
> > +     hop[3] = (tbl[3] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[3] & 0x00FFFFFF : defv;
> > +}
> > +
> > +#ifdef __cplusplus
> > +}
> > +#endif
> > +
> > +#endif /* _RTE_LPM_SCALAR_H_ */
>
> --
> Regards,
> Vladimir
Stanislaw Kardach May 27, 2022, 11:16 a.m. UTC | #3 
On Tue, May 24, 2022 at 6:28 PM Stanisław Kardach <kda@semihalf.com> wrote:
<snip>
> That said I wonder why do we have different const requirements for
> rte_lpm_lookup() and rte_lpm_lookupx4():
>   static inline int rte_lpm_lookup(struct rte_lpm *lpm, uint32_t ip,
> uint32_t *next_hop)
>   static inline void rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t
> ip, uint32_t hop[4], uint32_t defv);
> I think both should be const.
>
To re-iterate the question, should I also post a patch for changing
rte_lpm_lookup() to add "const" to "struct rte_lpm *lpm" argument?
rte_lpm_lookup_bulk_func() and rte_lpm_lookupx4() already take lpm as
const.
I'm pushing because otherwise I get a const discard warning in the
scalar version of rte_lpm_lookupx4() utilizing rte_lpm_lookup().

Best Regards,
Stanislaw Kardach
Vladimir Medvedkin May 27, 2022, 1:16 p.m. UTC | #4 
Hi Stanislaw,

On 27/05/2022 12:16, Stanisław Kardach wrote:
> On Tue, May 24, 2022 at 6:28 PM Stanisław Kardach <kda@semihalf.com> wrote:
> <snip>
>> That said I wonder why do we have different const requirements for
>> rte_lpm_lookup() and rte_lpm_lookupx4():
>>    static inline int rte_lpm_lookup(struct rte_lpm *lpm, uint32_t ip,
>> uint32_t *next_hop)
>>    static inline void rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t
>> ip, uint32_t hop[4], uint32_t defv);
>> I think both should be const.
>>
> To re-iterate the question, should I also post a patch for changing
> rte_lpm_lookup() to add "const" to "struct rte_lpm *lpm" argument?
> rte_lpm_lookup_bulk_func() and rte_lpm_lookupx4() already take lpm as
> const.
> I'm pushing because otherwise I get a const discard warning in the
> scalar version of rte_lpm_lookupx4() utilizing rte_lpm_lookup().

Since these are inline functions, there will be no problems with the 
ABI/API, so please add const to the *lpm argument.

Thanks!

> 
> Best Regards,
> Stanislaw Kardach
diff mbox series

Patch

diff --git a/doc/guides/rel_notes/release_22_07.rst b/doc/guides/rel_notes/release_22_07.rst
index 4ae91dd94d..73e8d632f2 100644
--- a/doc/guides/rel_notes/release_22_07.rst
+++ b/doc/guides/rel_notes/release_22_07.rst
@@ -70,6 +70,11 @@  New Features
   * Added AH mode support in lookaside protocol (IPsec) for CN9K & CN10K.
   * Added AES-GMAC support in lookaside protocol (IPsec) for CN9K & CN10K.
 
+* **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 eb91960e81..b5db6a353a 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..991b94e687
--- /dev/null
+++ b/lib/lpm/rte_lpm_scalar.h
@@ -0,0 +1,122 @@ 
+/* 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>
+#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)
+{
+	rte_xmm_t i24;
+	rte_xmm_t i8;
+	uint32_t tbl[4];
+	uint64_t pt, pt2;
+	const uint32_t *ptbl;
+
+	const rte_xmm_t mask8 = {
+		.u32 = {UINT8_MAX, UINT8_MAX, UINT8_MAX, UINT8_MAX}};
+
+	/*
+	 * RTE_LPM_VALID_EXT_ENTRY_BITMASK for 2 LPM entries
+	 * as one 64-bit value (0x0300000003000000).
+	 */
+	const uint64_t mask_xv =
+		((uint64_t)RTE_LPM_VALID_EXT_ENTRY_BITMASK |
+		(uint64_t)RTE_LPM_VALID_EXT_ENTRY_BITMASK << 32);
+
+	/*
+	 * RTE_LPM_LOOKUP_SUCCESS for 2 LPM entries
+	 * as one 64-bit value (0x0100000001000000).
+	 */
+	const uint64_t mask_v =
+		((uint64_t)RTE_LPM_LOOKUP_SUCCESS |
+		(uint64_t)RTE_LPM_LOOKUP_SUCCESS << 32);
+
+	/* get 4 indexes for tbl24[]. */
+	i24.x = ip;
+	i24.u32[0] >>= CHAR_BIT;
+	i24.u32[1] >>= CHAR_BIT;
+	i24.u32[2] >>= CHAR_BIT;
+	i24.u32[3] >>= CHAR_BIT;
+
+	/* extract values from tbl24[] */
+	ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[0]];
+	tbl[0] = *ptbl;
+	ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[1]];
+	tbl[1] = *ptbl;
+	ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[2]];
+	tbl[2] = *ptbl;
+	ptbl = (const uint32_t *)&lpm->tbl24[i24.u32[3]];
+	tbl[3] = *ptbl;
+
+	/* get 4 indexes for tbl8[]. */
+	i8.x = ip;
+	i8.u64[0] &= mask8.u64[0];
+	i8.u64[1] &= mask8.u64[1];
+
+	pt = (uint64_t)tbl[0] |
+		(uint64_t)tbl[1] << 32;
+	pt2 = (uint64_t)tbl[2] |
+		(uint64_t)tbl[3] << 32;
+
+	/* search successfully finished for all 4 IP addresses. */
+	if (likely((pt & mask_xv) == mask_v) &&
+			likely((pt2 & mask_xv) == mask_v)) {
+		*(uint64_t *)hop = pt & RTE_LPM_MASKX4_RES;
+		*(uint64_t *)(hop + 2) = pt2 & RTE_LPM_MASKX4_RES;
+		return;
+	}
+
+	if (unlikely((pt & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
+			RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
+		i8.u32[0] = i8.u32[0] +
+			(tbl[0] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
+		ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[0]];
+		tbl[0] = *ptbl;
+	}
+	if (unlikely((pt >> 32 & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
+			RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
+		i8.u32[1] = i8.u32[1] +
+			(tbl[1] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
+		ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[1]];
+		tbl[1] = *ptbl;
+	}
+	if (unlikely((pt2 & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
+			RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
+		i8.u32[2] = i8.u32[2] +
+			(tbl[2] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
+		ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[2]];
+		tbl[2] = *ptbl;
+	}
+	if (unlikely((pt2 >> 32 & RTE_LPM_VALID_EXT_ENTRY_BITMASK) ==
+			RTE_LPM_VALID_EXT_ENTRY_BITMASK)) {
+		i8.u32[3] = i8.u32[3] +
+			(tbl[3] & 0x00FFFFFF) * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
+		ptbl = (const uint32_t *)&lpm->tbl8[i8.u32[3]];
+		tbl[3] = *ptbl;
+	}
+
+	hop[0] = (tbl[0] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[0] & 0x00FFFFFF : defv;
+	hop[1] = (tbl[1] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[1] & 0x00FFFFFF : defv;
+	hop[2] = (tbl[2] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[2] & 0x00FFFFFF : defv;
+	hop[3] = (tbl[3] & RTE_LPM_LOOKUP_SUCCESS) ? tbl[3] & 0x00FFFFFF : defv;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _RTE_LPM_SCALAR_H_ */