[ewg] Re: the default CQ moderation parameters patch in OFED 1.3

[Eli Cohen]

On Sun, 2008-01-06 at 10:47 +0200, Or Gerlitz wrote:
> Hi Eli,
> 
> The patch below in OFED 1.3 does not check the device capabilities and hence
> always fail on non connectx systems. Can you fix it such that we will not
> get all those "why I we mthca0: failed to modify CQ params prints in the logs".
I chose to use KERN_INFO to indicate that it is not a sever situation.
Perhaps I should just remove the message.
> 
> Other then that and maybe even more important... I understand that it hard codes
> ipoib to ask for delivery of interrupt only after MAX (16 packets received, 10 us
> elapsed since first packet received), correct? so every simple ping-pong test that
> measures IPoIB latency under small packet rate will have now 10us added to its latency?
I did not notice that this deteriorates ping pong latency. Could you
check if it does?

> 
> I wonder if we can come up with simple way-in-the-middle here.
> 
> thanks,
> 
> Or.
> ------------------------------------
> Set default CQ moderation parameters
> 
> Set the default params to make sure they are applied. Otherwise
> we get poor performance.
> 
> Signed-off-by: Eli Cohen <eli at mellanox.co.il>
> 
> Index: ofa_kernel-1.3/drivers/infiniband/ulp/ipoib/ipoib_verbs.c
> ===================================================================
> --- ofa_kernel-1.3.orig/drivers/infiniband/ulp/ipoib/ipoib_verbs.c	2007-11-19 18:05:29.000000000 +0200
> +++ ofa_kernel-1.3/drivers/infiniband/ulp/ipoib/ipoib_verbs.c	2007-11-19 18:06:52.000000000 +0200
> @@ -181,6 +181,9 @@
>  		goto out_free_mr;
>  	}
> 
> +	if (ib_modify_cq(priv->cq, 16, 10))
> +		printk(KERN_INFO "%s: failed to modify CQ params\n", ca->name);
> +
>  	if (ib_req_notify_cq(priv->cq, IB_CQ_NEXT_COMP))
>  		goto out_free_cq;
>