Re: [PATCH v2] app/testpmd: optimized MAC swap by using neon intrinsics

[Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>]

> Improved MAC swap performance for ARM platform.
> The improvement was achieved by using neon intrinsics to save CPU cycles
> and doing swap for four packets at a time.
> The optimization had 15% - 20% throughput boost in testpmd MAC swap
> mode.
> 
> Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
> Reviewed-by: Gavin Hu <gavin.hu@arm.com>
> Reviewed-by: Phil Yang <phil.yang@arm.com>
> Acked-by: Jerin Jacob <jerinj@marvell.com>
> ---
> v2:
> * Defined idx_map as const.
> * Added file header line to indicate derivation from macswap_sse.h.
> 
>  app/test-pmd/macswap.c      |  4 +-
>  app/test-pmd/macswap_neon.h | 97
> +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 100 insertions(+), 1 deletion(-)  create mode 100644
> app/test-pmd/macswap_neon.h
> 
> diff --git a/app/test-pmd/macswap.c b/app/test-pmd/macswap.c index
> cbb41b7..71af916 100644
> --- a/app/test-pmd/macswap.c
> +++ b/app/test-pmd/macswap.c
> @@ -66,8 +66,10 @@
>  #include <rte_flow.h>
> 
>  #include "testpmd.h"
> -#ifdef RTE_ARCH_X86
> +#if defined(RTE_ARCH_X86)
>  #include "macswap_sse.h"
> +#elif defined(RTE_MACHINE_CPUFLAG_NEON) #include "macswap_neon.h"
>  #else
>  #include "macswap.h"
>  #endif
> diff --git a/app/test-pmd/macswap_neon.h b/app/test-
> pmd/macswap_neon.h new file mode 100644 index 0000000..bdf416a
> --- /dev/null
> +++ b/app/test-pmd/macswap_neon.h
> @@ -0,0 +1,97 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2019 Arm Limited
> + *
> + * Copyright(c) 2019 Intel Corporation
> + *
> + * Derived do_macswap implementation from app/test-pmd/macswap_sse.h
> +*/
> +
> +#ifndef _MACSWAP_NEON_H_
> +#define _MACSWAP_NEON_H_
> +
> +#include "macswap_common.h"
> +#include "rte_vect.h"
> +
> +static inline void
> +do_macswap(struct rte_mbuf *pkts[], uint16_t nb,
> +		struct rte_port *txp)
> +{
> +	struct ether_hdr *eth_hdr[4];
> +	struct rte_mbuf *mb[4];
> +	uint64_t ol_flags;
> +	int i;
> +	int r;
> +	uint8x16_t v0, v1, v2, v3;
> +	/**
> +	 * Index map be used to shuffle the 16 bytes.
> +	 * byte 0-5 will be swapped with byte 6-11.
> +	 * byte 12-15 will keep unchanged.
> +	 */
> +	const uint8x16_t idx_map = {6, 7, 8, 9, 10, 11, 0, 1, 2, 3, 4, 5,
> +				12, 13, 14, 15};
> +
> +	ol_flags = ol_flags_init(txp->dev_conf.txmode.offloads);
> +	vlan_qinq_set(pkts, nb, ol_flags,
> +			txp->tx_vlan_id, txp->tx_vlan_id_outer);
> +
> +	i = 0;
> +	r = nb;
> +
> +	while (r >= 4) {
> +		if (r >= 8) {
> +			rte_prefetch0(rte_pktmbuf_mtod(pkts[i + 4], void *));
> +			rte_prefetch0(rte_pktmbuf_mtod(pkts[i + 5], void *));
> +			rte_prefetch0(rte_pktmbuf_mtod(pkts[i + 6], void *));
> +			rte_prefetch0(rte_pktmbuf_mtod(pkts[i + 7], void *));
> +		}
> +
> +		mb[0] = pkts[i++];
> +		eth_hdr[0] = rte_pktmbuf_mtod(mb[0], struct ether_hdr *);
> +
> +		mb[1] = pkts[i++];
> +		eth_hdr[1] = rte_pktmbuf_mtod(mb[1], struct ether_hdr *);
> +
> +		mb[2] = pkts[i++];
> +		eth_hdr[2] = rte_pktmbuf_mtod(mb[2], struct ether_hdr *);
> +
> +		mb[3] = pkts[i++];
> +		eth_hdr[3] = rte_pktmbuf_mtod(mb[3], struct ether_hdr *);
> +
> +		v0 = vld1q_u8((uint8_t const *)eth_hdr[0]);
> +		v1 = vld1q_u8((uint8_t const *)eth_hdr[1]);
> +		v2 = vld1q_u8((uint8_t const *)eth_hdr[2]);
> +		v3 = vld1q_u8((uint8_t const *)eth_hdr[3]);
> +
> +		v0 = vqtbl1q_u8(v0, idx_map);
> +		v1 = vqtbl1q_u8(v1, idx_map);
> +		v2 = vqtbl1q_u8(v2, idx_map);
> +		v3 = vqtbl1q_u8(v3, idx_map);
> +
> +		vst1q_u8((uint8_t *)eth_hdr[0], v0);
> +		vst1q_u8((uint8_t *)eth_hdr[1], v1);
> +		vst1q_u8((uint8_t *)eth_hdr[2], v2);
> +		vst1q_u8((uint8_t *)eth_hdr[3], v3);
> +
> +		mbuf_field_set(mb[0], ol_flags);
> +		mbuf_field_set(mb[1], ol_flags);
> +		mbuf_field_set(mb[2], ol_flags);
> +		mbuf_field_set(mb[3], ol_flags);
> +		r -= 4;
> +	}
> +
> +	for ( ; i < nb; i++) {
> +		if (i < nb - 1)
> +			rte_prefetch0(rte_pktmbuf_mtod(pkts[i+1], void *));
> +		mb[0] = pkts[i];
> +		eth_hdr[0] = rte_pktmbuf_mtod(mb[0], struct ether_hdr *);
> +
> +		/* Swap dest and src mac addresses. */
> +		v0 = vld1q_u8((uint8_t const *)eth_hdr[0]);
> +		v0 = vqtbl1q_u8(v0, idx_map);
> +		vst1q_u8((uint8_t *)eth_hdr[0], v0);
> +
> +		mbuf_field_set(mb[0], ol_flags);
> +	}
> +}
> +
> +#endif /* _MACSWAP_NEON_H_ */
> --
> 2.7.4

Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>