Re: [dpdk-dev] [PATCH v2 1/3] net/af_xdp: allow bigger batch sizes

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 3/9/2021 10:19 AM, Ciara Loftus wrote:
> Prior to this commit, the maximum batch sizes for zero-copy and copy-mode
> rx and copy-mode tx were set to 32. Apart from zero-copy tx, the user
> could never rx/tx any more than 32 packets at a time and without inspecting
> the code the user wouldn't be aware of this.
> 
> This commit removes these upper limits placed on the user and instead
> sets an internal batch size equal to the default ring size (2048). Batches
> larger than this are still processed, however they are split into smaller
> batches similar to how it's done in other drivers. This is necessary
> because some arrays used during rx/tx need to be sized at compile-time.
> 
> Allowing a larger batch size allows for fewer batches and thus larger bulk
> operations, fewer ring accesses and fewer syscalls which should yield
> improved performance.
> 
> Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
> ---
>   drivers/net/af_xdp/rte_eth_af_xdp.c | 67 ++++++++++++++++++++++++-----
>   1 file changed, 57 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
> index 3957227bf0..be524e4784 100644
> --- a/drivers/net/af_xdp/rte_eth_af_xdp.c
> +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
> @@ -66,8 +66,8 @@ RTE_LOG_REGISTER(af_xdp_logtype, pmd.net.af_xdp, NOTICE);
>   #define ETH_AF_XDP_DFLT_START_QUEUE_IDX	0
>   #define ETH_AF_XDP_DFLT_QUEUE_COUNT	1
>   
> -#define ETH_AF_XDP_RX_BATCH_SIZE	32
> -#define ETH_AF_XDP_TX_BATCH_SIZE	32
> +#define ETH_AF_XDP_RX_BATCH_SIZE	XSK_RING_CONS__DEFAULT_NUM_DESCS
> +#define ETH_AF_XDP_TX_BATCH_SIZE	XSK_RING_CONS__DEFAULT_NUM_DESCS
> 

Just to double check, can there be a library version that these macros not 
defined, should it be checked?