[dpdk-dev] [disscussion] A problem about dpdk backup-mode bond switching with mlx4 VF devices

[Adrien Mazarguil]

On Tue, Apr 17, 2018 at 06:40:20AM +0000, chenchanghu wrote:
> 
> Hi,
>          When I used the mlx4 pmd, I meet a problem about mlx4 VF bond switching which bond mod is backup-mode . The detail test is descripted below.
> 1.Test environmemt infomation:
>   a. Linux distribution: CentOS
>   b. dpdk version: dpdk-16.04
>   c. Ethernet device : mlx4 VF
>   d. pmd info: mlx4 poll-mode-driver
> 
> 2.Test step:
>   a. we bond the mlx4 VF Ethernet device eth7,eth8 into backup-mode by dpdk application. Eth7 and eth8 are both active, and  eth7 is the primary device.
>   b. As we know,  the device eth7 , eth8 are also  visible by kernel driver mlx4_en.
>   c. Then we config the Ethernet device eth7 down by the command ' ifconfig eth7 down', the expect result is the bond primary device will  not switch.
>   d. However we find the dpdk bond primary device switch to eth8 by dpdk maintenance interface one time in all 20 test times.
> 
> 3.Question:
>    Is the VF up or down State of kernel interface has some relations to user-space state? For example, when ifconfig eth7 down, and the user-space will change to down state too.

Yes, this is expected. Netdevices and the mlx4 DPDK PMD share a common link
status. Bringing a netdevice down causes link status to be down for all its
users. This behavior is documented [1].

[1] http://dpdk.org/doc/guides/nics/mlx4.html#run-time-configuration

-- 
Adrien Mazarguil
6WIND