On 05/01/2018 09:41, hiren panchasara wrote:
IIRC, with 'RSS' in kernconf, most NIC drivers and stack should do the
right thing. Look at drivers and also conn startup code in TCP as I
recall it doing the flowid mapping correctly when stream originated from
the other side and had flowid assigned to it by the NIC.
I am mostly concerned about the overhead of manual calculation but my
knowledge is a bit rusty right now and lagg has always been special so
please try this out and see.
I've not been able to find any such option:
head:src> grep -ri rss sys/amd64/conf/
head:src>
Any other ideas on where it might be or is it just the default on HEAD?
That said the more I think / talk about this the more I believe manual
calculation is the right option for LACP.
The reason I believe this is:
* When configuring LACP in a network knowing the hash method is
important, so using an unknown "flowid" based hash could produce
unexpected results.
* There's no easy way (possibly no way at all) to determine the flowid
from the HW for the first packet of a new outbound connection
* Having the hash algorithm vary for inbound and outbound connections
increases the chance of unexpected results.
* LCAP combines NIC's of even speed, however they can be different HW
so there's no guarantee that the partaking ports use the same flowid
calculation, again increasing the chance of a problem.
So as mentioned in a previous reply the more I think about the more
believe flowid can't be successfully used as a hash source for LACP or
loadbalance.
What do others think, am I missing something?
Regards
Steve
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