On Thu, 22 Apr 2021 12:24:32 +0200
Magnus Karlsson [off-list ref] wrote:

On Wed, Apr 21, 2021 at 5:39 PM Jesper Dangaard Brouer
[off-list ref] wrote:

quoted

On Wed, 21 Apr 2021 16:12:32 +0200
Magnus Karlsson [off-list ref] wrote:
 

[...]

quoted

quoted

more than I get.  

I clearly have a bug in the i40e driver.  As I wrote later, I don't see
any packets transmitted for XDP_TX.  Hmm, I using Mel Gorman's tree,
which contains the i40e/ice/ixgbe bug we fixed earlier.

Something is wrong with i40e, I changed git-tree to net-next (at
commit 5d869070569a) and XDP seems to have stopped working on i40e :-(

$ uname -a
Linux broadwell 5.12.0-rc7-net-next+ #600 SMP PREEMPT Thu Apr 22 15:13:15 CEST 2021 x86_64 x86_64 x86_64 GNU/Linux

When I load any XDP prog almost no packets are let through:

 [kernel-bpf-samples]$ sudo ./xdp1 i40e2
 libbpf: elf: skipping unrecognized data section(16) .eh_frame
 libbpf: elf: skipping relo section(17) .rel.eh_frame for section(16) .eh_frame
 proto 17:          1 pkt/s
 proto 0:          0 pkt/s
 proto 17:          0 pkt/s
 proto 0:          0 pkt/s
 proto 17:          1 pkt/s

On the same system my mlx5 NIC works fine:

 [kernel-bpf-samples]$ sudo ./xdp1 mlx5p1
 libbpf: elf: skipping unrecognized data section(16) .eh_frame
 libbpf: elf: skipping relo section(17) .rel.eh_frame for section(16) .eh_frame
 proto 17:   10984608 pkt/s
 proto 17:   24374656 pkt/s
 proto 17:   24339904 pkt/s

quoted

The call to xdp_convert_buff_to_frame() fails, but (see below) that
error is simply converted to I40E_XDP_CONSUMED.  Thus, not even the
'trace_xdp_exception' will be able to troubleshoot this.  You/Intel
should consider making XDP_TX errors detectable (this will also happen
if TX ring don't have room).  

This is not good. Will submit a fix. Thanks for reporting Jesper.

Usually I use this command to troubleshoot:
  sudo ./xdp_monitor --stats 

But as driver i40e doesn't call the 'trace_xdp_exception' then I don't
capture any error this way.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer