On Wed, 6 Feb 2019 16:40:14 +0100
Håkon Bugge [off-list ref] wrote:

Jack,

A major contributor to the long processing time in the PF driver
proxying QP1 packets is:

create_pv_resources
   -> ib_create_cq(ctx->ib_dev, mlx4_ib_tunnel_comp_handler,  
                               NULL, ctx, cq_size, 0);

That is, comp_vector is zero.

Due to commit 6ba1eb776461 ("IB/mlx4: Scatter CQs to different EQs"),
the zero comp_vector has the intent of let the mlx4_core driver
select the least used vector.

But, in mlx4_ib_create_cq(), we have:

        pr_info("eq_table: %p\n", dev->eq_table);
        if (dev->eq_table) {
		vector = dev->eq_table[mlx4_choose_vector(dev->dev,
vector, ibdev->num_comp_vectors)];
        }

        cq->vector = vector;

and dev->eq_table is NULL, so all the CQs for the proxy QPs get
comp_vector zero.

I have to make some reservations, as this analysis is based on uek4,
but I think the code here is equal upstream, but need to double check.


Thxs, Håkon

Hi Hakon and Jason,
I was ill today (bad cold, took antihistamines all day, which knocked
me out).
I'll get to this tomorrow.

-Jack