Re: [PATCH] IB/ipoib: improve latency in ipoib/cm connection formation

[Jason Gunthorpe <jgg@nvidia.com>]

On Tue, Jan 26, 2021 at 08:28:18PM +0000, Haakon Bugge wrote: 
> >>> @@ -1122,7 +1123,8 @@ static int ipoib_cm_modify_tx_init(struct
> >> net_device *dev,
> >>> 	struct ipoib_dev_priv *priv = ipoib_priv(dev);
> >>> 	struct ib_qp_attr qp_attr;
> >>> 	int qp_attr_mask, ret;
> >>> -	ret = ib_find_pkey(priv->ca, priv->port, priv->pkey,
> >> &qp_attr.pkey_index);
> >>> +	ret = ib_find_cached_pkey(priv->ca, priv->port, priv->pkey,
> >>> +						&qp_attr.pkey_index);
> >> 
> >> ipoib interfaces are locked to a single pkey, you should be able to get the
> >> pkey index that was determined at link up time and use it here instead of
> >> searching anything
> 
> Isn't possible to:
> 
> # ip link add DEVICE name NAME type ipoib [ pkey PKEY ] 
> 
> ?

Yes, and each new netdev that spawns has a fixed pkey that doesn't
change for the life of the netdev

Jason