On Friday 04 December 2015 11:12:30 Eric Dumazet wrote:

On Fri, 2015-12-04 at 19:45 +0100, Gregory CLEMENT wrote:

quoted

With this patch each CPU is associated with its own set of TX queues. In
the same time the SKB received in mvneta_tx is bound to the queue
associated to the CPU sending the data. Thanks to this the next IRQ will
be received on the same CPU allowing sending more data.

It will also allow to have a more predictable behavior regarding
throughput and latency when having multiple threads sending out data on
different CPUs.

As an example on Armada XP GP, with an iperf bound to a CPU and a ping
bound to another CPU, without this patch the ping round trip was about
2.5ms (and could reach 3s!), whereas with this patch it was around
0.7ms (and sometime it went to 1.2ms).

This really looks like you need something smarter than pfifo_fast qdisc,
and maybe BQL (I did not check if this driver already implements this)

I suggested this change as well as the BQL implementation that Marcin did.
I believe he hasn't posted that yet while he's doing some more testing,
but it should come soon.

	Arnd