[dpdk-dev] [PATCH v2 1/2] net/ixgbe: calculate the correct number of received packets in bulk alloc function

[Ananyev, Konstantin]

> 
> To get better performance, Rx bulk alloc recv function will scan 8 descs
> in one time, but the statuses are not consistent on ARM platform because
> the memory allocated for Rx descriptors is cacheable hugepages.
> This patch is to calculate the number of received packets by scan DD bit
> sequentially, and stops when meeting the first packet with DD bit unset.
> 
> Signed-off-by: Jianbo Liu <jianbo.liu at linaro.org>
> ---
>  drivers/net/ixgbe/ixgbe_rxtx.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ixgbe/ixgbe_rxtx.c b/drivers/net/ixgbe/ixgbe_rxtx.c
> index 36f1c02..613890e 100644
> --- a/drivers/net/ixgbe/ixgbe_rxtx.c
> +++ b/drivers/net/ixgbe/ixgbe_rxtx.c
> @@ -1460,17 +1460,19 @@ static inline int __attribute__((always_inline))
>  	for (i = 0; i < RTE_PMD_IXGBE_RX_MAX_BURST;
>  	     i += LOOK_AHEAD, rxdp += LOOK_AHEAD, rxep += LOOK_AHEAD) {
>  		/* Read desc statuses backwards to avoid race condition */
> -		for (j = LOOK_AHEAD-1; j >= 0; --j)
> +		for (j = 0; j < LOOK_AHEAD; j++)
>  			s[j] = rte_le_to_cpu_32(rxdp[j].wb.upper.status_error);
> 
> -		for (j = LOOK_AHEAD - 1; j >= 0; --j)
> -			pkt_info[j] = rte_le_to_cpu_32(rxdp[j].wb.lower.
> -						       lo_dword.data);
> +		rte_smp_rmb();
> 
>  		/* Compute how many status bits were set */
> -		nb_dd = 0;
> -		for (j = 0; j < LOOK_AHEAD; ++j)
> -			nb_dd += s[j] & IXGBE_RXDADV_STAT_DD;
> +		for (nb_dd = 0; nb_dd < LOOK_AHEAD &&
> +				(s[nb_dd] & IXGBE_RXDADV_STAT_DD); nb_dd++)
> +			;
> +
> +		for (j = 0; j < nb_dd; j++)
> +			pkt_info[j] = rte_le_to_cpu_32(rxdp[j].wb.lower.
> +						       lo_dword.data);
> 
>  		nb_rx += nb_dd;
> 
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com>

> 1.8.3.1