Re: [PATCH v4 4/4] net/mlx5: enforce Tx num of segments limitation

Hi Yongseok,

Wednesday, September 13, 2017 10:52 PM, Yongseok Koh:

quoted

+/* Maximum number of DS in WQE. */
+#define MLX5_MAX_DS 63

How about make it consistent with MLX5_MPW_DSEG_MAX by naming
MLX5_DSEG_MAX?

It doesn't have the same meaning. 

The MLX5_MPW_DSEG_MAX is to limit the number of mbuf segments (buf->nb_segs) for multi packet wqe.  The inline part  is taken into account differently. 
The MLX_MAX_DS is to limit the number data segments (i.e. MLX5_WQE_DWORD_SIZE) that could be set into a WQE. This includes everything (inline, ctrl seg, eth seg, pointers).
For the regular Tx burst there are many options for different inline sizes which impact on the max number of mbuf segments possible. 

BTW - am still not sure why we have the MLX5_MPW_DSEG_MAX limitation.