Re: [PATCH 1/2] app/testpmd: add custom topology command

[Wisam Monther <wisamm@mellanox.com>]

PSB.

BRs,
Wisam Jaddo

-----Original Message-----
From: Kevin Traynor [mailto:ktraynor@redhat.com] 
Sent: Wednesday, May 16, 2018 3:41 PM
To: Wisam Monther; jingjing.wu@intel.com; wenzhuo.lu@intel.com; Thomas Monjalon
Cc: Raslan Darawsheh; dev@dpdk.org; Shahaf Shuler
Subject: Re: [dpdk-dev] [PATCH 1/2] app/testpmd: add custom topology command

On 05/15/2018 03:05 PM, Wisam Monther wrote:
> Hey Kevin,
> 
> What if I have 10 ports and want all 9 ports to forward packets to 
> port 0, this cannot done in paired.
> But with this topo the user can overwrite the topo.
> E.g:
> - Set custom-topo 1 0
> Will make those paired and those two as active only.
> 
> - set custom-topo 2 0
> Will make those two as paired, but still port one will forward packets 
> to 0.
> And the active ports will be 3 ports (0,1,2) And so on...
> With this topo you can create your own topo. (Mixed between all topos 
> or even non-pattern topo for any usage) In my case its needed for 
> representors and virtio.
> 
> Any traffic coming from representors/vhost (from VM) need to be 
> forwarded from PF/phy port to the wire.
> 

Thanks for sharing the use case.

Will it be an issue that multiple cores may be sending to the same TxQ?
I didn't check to see if there is locking provided in the app.

[Wisam] I've tested such case recently, and yes it will cause a seg. Fault in this solution, since multiple cores will access same queues.
I'm currently working on a fix for it, I'm planning to map single queues for each core with custom topology to avoid such scenario.


> This new topo is useful for such cases.
> 
> BRs,
> Wisam jaddo
>