Re: [dpdk-dev] [PATCH v1] app/testpmd: optimized MAC swap by using neon intrinsics

[Jerin Jacob Kollanukkaran <jerinj@marvell.com>]

On Mon, 2019-03-11 at 16:14 +0800, Ruifeng Wang wrote:
> -------------------------------------------------------------------
> ---
> 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>
> ---
>  app/test-pmd/macswap.c      |  4 +-
>  app/test-pmd/macswap_neon.h | 93
> +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 96 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
> 
> +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.
> +	 */
> +	uint8x16_t idx_map = {6, 7, 8, 9, 10, 11, 0, 1, 2, 3, 4, 5,
> +				12, 13, 14, 15};

Nit: I think, we can make it as "const uint8x16_t idx_map".

Other than that it looks good to me.
Regarding the performance, I have tested with two SoCs.

octeontx: +13% improvement
octeontx2: +46% improvement


Acked-by: Jerin Jacob <jerinj@marvell.com>