Re: [PATCH] mlx4: allow for 4K mtu configuration of IB ports

[Or Gerlitz <ogerlitz-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>]

Roland Dreier wrote:
> Bob Pearson <rpearson-klaOcWyJdxkshyMvu7JE4pqQE7yCjDx5@public.gmane.org> wrote:
>> With lash+mesh redsky required 6-7 VLs to wire up without deadlocks. I think
>> that Jim's version uses 8 SLs but only 2VLs to work.
>> If someone was using a torus and also wanted to support QOS and also wanted
>> to separate multicast and management on a separate VL to be absolutely sure
>> that there is no possibility of a deadlock you might end up with #QOS * 2 +
>> 1 which would be 5 using the current algorithm.

> But again you don't need all those VLs on the HCAs' links, do you?

Jason Gunthorpe wrote:
> Routing algorithms only need VLs on interswitch links, not on HCA to
> switch links. The only use of the HCA to switch VLs is for QoS. Mesh
> topologies can usually be routed with only two VLs, but you need alot
> of SLs to make that work.

Bob, Jim, Alex

I wasn't sure if the SL-to-VL mapping done by open SM is dictated by the 
directives @ the user config file or if the routing algorithm is "VL 
aware" but the routing engine? if the latter, do interswitch links use 
different mapping vs. HCA - switch links?

Or.
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