[ovs-discuss] OVS DPDK: Failed to create memory pool for netdev

[Flavio Leitner]

On Tue, 5 Nov 2019 18:47:09 +0000
"Tobias Hofmann \(tohofman\) via discuss" <ovs-discuss at openvswitch.org>
wrote:

> Hi Flavio,
> 
> thanks for the insights! Unfortunately, I don't know about the pdump
> and its relation to the ring.

pdump dumps packets from dpdk ports into rings/mempools, so that you
can inspect/use the traffic:
https://doc.dpdk.org/guides/howto/packet_capture_framework.html

But I looked at the dpdk sources now and I don't see it allocating any
memory when the library is initialized, so this is likely a red herring.

> Can you please specify where I can see that the port is not ready
> yet? Is that these three lines:
> 
> 2019-11-02T14:14:23.094Z|00070|dpdk|ERR|EAL: Cannot find unplugged
> device (0000:08:0b.2)

The above shows the device is not ready/bound yet.


> 2019-11-02T14:14:23.094Z|00071|netdev_dpdk|WARN|Error attaching
> device '0000:08:0b.2' to DPDK
> 2019-11-02T14:14:23.094Z|00072|netdev|WARN|dpdk-p0: could not set
> configuration (Invalid argument)
> 
> As far as I know, the ring allocation failure that you mentioned
> isn't necessarily a bad thing since it just indicates that DPDK
> reduces something internally (I can't remember what exactly it was)
> to support a high MTU with only 1GB of memory.

True for the memory allocated for DPDK ports. However, there is a
minimum which if it's not there, the mempool allocation will fail.

> I'm wondering now if it might help to change the timing of when
> openvswitch is started after a system reboot to prevent this problem
> as it only occurs after reboot. Do you think that this approach might
> fix the problem?

It will help to get the i40e port working, but that "ring error"
will continue as you see after restarting anyways.

I don't know the other interface types, maybe there is another
interface failing which is not in the log. Do you see any error
reported in 'ovs-vsctl show' after the restart?

fbl