[ofa-general] RE: [UPDATE] [V3] [PATCH 3/3] ib/ipoib: IPoIB-UD RX S/G supportfor 4K MTU

[Eli Cohen]

Hi Shirley,

I have reviewed the patches against Roland's tree and have the following
comments:

1. I see that there are a few if statements added on the fast pass and I
am concerned they might hurt performance of slow UDP messages.
Unfortunately I have not been able to test with an SM defining the
broadcast group to 4K MTU (currently opensm uses 2K).

2. The usage of ipoib_ud_skb_put_frags() seems to be redundant and will
only hurt performance since you would never reuse anything from the old
SKB. This is because the headlen is 40 bytes for GRH and the rest of the
data is in the first (and only) fragment.

3. I think it would be better to allocate room for real data in the head
of the SKB since the tcp/ip stack seems to have less overhead if the
headers are on the linear data.

4. I would consider using a pre-allocated buffer for the GRH of all
received data (not as part of the SKB).