Re: [RFC PATCH 00/10] Make XPS usable within ixgbe

On 7/3/2012 3:30 PM, Tom Herbert wrote:

Hi Alexander,

Thanks for this work!

Some general comments:

1) skb_tx_hash is called from a handful of drivers (bnx2x, ixgbe,
mlx4, and bonding).  Would it make sent to call xps_get_cpu from that
function (unfortunately the use of ndo_select_queue is likely
bypassing xps unnecessarily in these drivers).

I suspect we can get rid of the select_queue cases for at least
bnx2x, ixgbe, and mlx4. We might need to be a bit clever to resolve
the mlx4 case but should be doable.

Anyways I would like to see these cases refactored away.

2) Instead of (or maybe in addition to) allowing driver to program xps
maps, we could parameterize get_xps_cpu to optionally include a bit
map of acceptable queues.  This would be useful to define a
hierarchical queue selection (like first choose a set for QoS, then
amongst those chose one base on xps).

Agreed.

We likely need something like (2) to get this to work with mqprio and
other QOS schemes in use.

.John