linux-kernel - Re: [PATCH] mlx4_ib: Increase the timeout for CM cache

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Message-ID: <20190206200229.00002e2f@dev.mellanox.co.il>
Date:   Wed, 6 Feb 2019 20:02:29 +0200
From:   jackm <jackm@....mellanox.co.il>
To:     Håkon Bugge <haakon.bugge@...cle.com>
Cc:     Jason Gunthorpe <jgg@...pe.ca>, netdev@...r.kernel.org,
        OFED mailing list <linux-rdma@...r.kernel.org>,
        rds-devel@....oracle.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mlx4_ib: Increase the timeout for CM cache

On Wed, 6 Feb 2019 16:40:14 +0100
Håkon Bugge <haakon.bugge@...cle.com> 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