On Thu, Jan 06, 2011 at 05:38:01PM -0500, Jesse Gross wrote:

[ snip ]

I know that everyone likes a nice netperf result but I agree with
Michael that this probably isn't the right question to be asking.  I
don't think that socket buffers are a real solution to the flow
control problem: they happen to provide that functionality but it's
more of a side effect than anything.  It's just that the amount of
memory consumed by packets in the queue(s) doesn't really have any
implicit meaning for flow control (think multiple physical adapters,
all with the same speed instead of a virtual device and a physical
device with wildly different speeds).  The analog in the physical
world that you're looking for would be Ethernet flow control.
Obviously, if the question is limiting CPU or memory consumption then
that's a different story.

Point taken. I will see if I can control CPU (and thus memory) consumption
using cgroups and/or tc.

This patch also double counts memory, since the full size of the
packet will be accounted for by each clone, even though they share the
actual packet data.  Probably not too significant here but it might be
when flooding/mirroring to many interfaces.  This is at least fixable
(the Xen-style accounting through page tracking deals with it, though
it has its own problems).

Agreed on all counts.