Hello,

I’m trying to attach a DPDK port with an mtu_size of 9216 to a bridge. For this 
purpose, I have allocated 512 HugePages of size 2MB for OVS (1GB in total).
Doing so will constantly fail, two workarounds to get it working were either to 
decrease the MTU size to 1500 or to increase the total amount of HugePage 
memory to 3GB.

Actually, I did expect the setup to also work with just 1GB because if the 
amount of memory is not sufficient, OVS will try to halve the number of buffers 
until 16K.
However, inside the logs I couldn’t find any details regarding this. The only 
error message I observed was:
netdev_dpdk|ERR|Failed to create memory pool for netdev dpdk-p0, with MTU 9216 
on socket 0: Invalid argument

That log message is weird as I would have expected an error message saying 
something like ‘could not reserve memory’ but not ‘Invalid argument’.
I then found this very similar bug on Openstack: 
https://bugs.launchpad.net/starlingx/+bug/1796380

After having read this, I tried the exact same setup as described above but 
this time with HugePages of size 1GB instead of 2MB. In this scenario, it also 
worked with just 1GB of memory reserved for OVS.
Inside the logs I could observe this time:
2019-04-02T22:55:31.849Z|00098|dpdk|ERR|RING: Cannot reserve memory
2019-04-02T22:55:32.019Z|00099|dpdk|ERR|RING: Cannot reserve memory
2019-04-02T22:55:32.200Z|00100|netdev_dpdk|INFO|Virtual function detected, 
HW_CRRC_STRIP will be enabled
2019-04-02T22:55:32.281Z|00101|netdev_dpdk|INFO|Port 0: f6:e9:29:4d:f9:cf
2019-04-02T22:55:32.281Z|00102|dpif_netdev|INFO|Core 1 on numa node 0 assigned 
port 'dpdk-p0' rx queue 0 (measured processing cycles 0).

The two times where OVS cannot reserve memory are, I guess, the two times where 
it has to halve the number of buffers to get it working.
My question now is, is the fact that it does not work for 2MB HugePages a bug? 
Also, is the error message in the first log extract the intended one?

My version numbers:

  *   CentOS 7.6
  *   Open vSwitch version: 2.9.3
  *   DPDK version: 17.11
  *   System has a single NUMA node.

Thank you
Tobias
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  • [ovs-discuss]... Tobias Hofmann -T (tohofman - AAP3 INC at Cisco) via discuss
    • Re: [ovs... Ian Stokes
      • Re: ... Tobias Hofmann -T (tohofman - AAP3 INC at Cisco) via discuss
        • ... Tobias Hofmann -T (tohofman - AAP3 INC at Cisco) via discuss
          • ... Ian Stokes
            • ... Tobias Hofmann -T (tohofman - AAP3 INC at Cisco) via discuss

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