[dpdk-dev] Mellanox Flow Steering

[Raghav Sethi <raghavs@CS.Princeton.EDU>]

Hi folks,

I'm trying to use the flow steering features of the Mellanox card to
effectively use a multicore server for a benchmark.

The system has a single-port Mellanox ConnectX-3 EN, and I want to use 4 of
the 32 cores present and 4 of the 16 RX queues supported by the hardware
(i.e. one RX queue per core).

I assign RX queues to each of the cores, but obviously without flow
steering (all the packets have the same IP and UDP headers, but different
dest MACs in the ethernet headers) each of the packets hits one core. I've
set up the client such that it sends packets with a different destination
MAC for each RX queue (e.g. RX queue 1 should get 10:00:00:00:00:00, RX
queue 2 should get 10:00:00:00:00:01 and so on).

I try to accomplish this by using ethtool to set flow steering rules (e.g.
ethtool -U p7p1 flow-type ether dst 10:00:00:00:00:00 action 1 loc 1,
ethtool -U p7p1 flow-type ether dst 10:00:00:00:00:01 action 2 loc 2..).

As soon as I set up these rules though, packets matching them just stop
hitting my application. All other packets go through, and removing the
rules also causes the packets to go through. I'm pretty sure my application
is looking at all the queues, but I tried changing the rules to try a rule
for every single destination RX queue (0-16), and that doesn't work either.

If it helps, my code is based on the l2fwd sample application, and is here:
https://gist.github.com/raghavsethi/416fb77d74ccf81bd93e

Also, I added the following to my /etc/init.d: options mlx4_core
log_num_mgm_entry_size=-1, and restarted the driver before any of these
tests.

Any ideas what might be causing my packets to drop? In case this is a
Mellanox issue, should I be talking to their customer support?

Best,
Raghav Sethi