Chris
thank you for the pointers!
Some preliminary tests reprogramming rss key and redirection table are 
promising.

Regards
Alfredo

On May 28, 2012, at 7:23 PM, Chris Wakelin wrote:

> I've been looking at the issue of multiqueue RSS hashing in ixgbe (and
> presumably igb), which is one of the things libzero is supposed to help
> with.
> 
> The problem is that (at least in some cases) traffic from X->Y may end
> up in a different queue, and therefore different CPU core, to that from
> Y->X.
> 
> I found some patches that are supposed to help
> 
> http://www.mail-archive.com/[email protected]/msg04364.html
> 
> and
> 
> http://kerneltrap.org/mailarchive/linux-netdev/2010/12/18/6292110
> 
> So it appears that the hashing algorithm can be modified in the driver!
> 
> In the ensuing discussion on kerneltrap.org
> 
> http://kerneltrap.org/mailarchive/linux-netdev/2011/1/3/6292774
> 
> the author says that when flow-director is enabled, the patch isn't needed.
> 
> So if I turn on "ntuple" with "ethtool -K eth1 ntuple: on", with no
> filtering rules, would that mean the queues now match?
> 
> My testing has been pretty inconclusive. Certainly, even in the default
> modes, I get *some* traffic where X->Y and Y->X are in the same queue,
> but of course you'd probably expect that to happen in 1/N cases for N
> queues.
> 
> Best Wishes,
> Chris
> 
> -- 
> --+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+-
> Christopher Wakelin,                           [email protected]
> IT Services Centre, The University of Reading,  Tel: +44 (0)118 378 2908
> Whiteknights, Reading, RG6 6AF, UK              Fax: +44 (0)118 975 3094
> _______________________________________________
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