[openib-general] Re: [PATCH] repost: IPoIB queue size tune patch

[Roland Dreier]

    Shirley> IPoIB is not a real driver. Packets can be dropped from
    Shirley> dev xmit queue to QPs send queue directly. Why we use
    Shirley> tx_ring to induce overhead in send path?

I don't follow how you can do this -- we need to keep track of skb so
that when the send completes, we can release it.  As Michael said we
also need to keep track of DMA mapping so that we can unmap after the
send is done.  This implies some sort of data structure for each
packet in the send queue, and allocating a circular buffer up front
seems at least as good as keeping a linked list to me.

 - R.