Re: ixgbe tuning reset when XDP is setup

On 15 Dec 2017, at 17:51, Alexander Duyck [off-list ref] wrote:

On Fri, Dec 15, 2017 at 8:03 AM, John Fastabend
[off-list ref] wrote:

quoted

On 12/15/2017 07:53 AM, David Miller wrote:

quoted

From: Eric Leblond <redacted>
Date: Fri, 15 Dec 2017 11:24:46 +0100

quoted

Hello,

When using an ixgbe card with Suricata we are using the following
commands to get a symmetric hash on RSS load balancing:

./set_irq_affinity 0-15 eth3
ethtool -X eth3 hkey 6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A:6D:5A equal 16
ethtool -x eth3
ethtool -n eth3

Then we start Suricata.

In my current experiment on XDP, I have Suricata that inject the eBPF
program when starting. The consequence of that when using an ixgbe card
is that the load balancing get reset and all interrupts are reaching
the first core.

This definitely should _not_ be a side effect of enabling XDP on a device.

Agreed, CC Emil and Alex we should restore these settings after the
reconfiguration done to support a queue per core.

.John

So the interrupt configuration has to get reset since we have to
assign 2 Tx queues for every Rx queue instead of the 1-1 that was
previously there. That is a natural consequence of rearranging the
queues as currently happens. The issue is the q_vectors themselves
have to be reallocated. The only way to not make that happen would be
to pre-allocate the Tx queues for XDP always.

Also just to be clear we are talking about the interrupts being reset,
not the RSS key right? I just want to make sure that is what we are
talking about.

Yes.
From the tests we did I only observed the IRQs being all reset to the first CPU after Suricata started.

Thanks.

- Alex