Re: [patch net-next v4 0/4] return offloaded stats as default and expose original sw stats

David Ahern
2016-06-17T13:48:44Z

On 6/17/16 2:24 AM, Jiri Pirko wrote:
>
> The problem we try to handle is different, it's about offloaded
> forwarded packets which are not seen by kernel. Let me try to draw it :)
>
> port1 port2 (HW stats are counted here)
> \ /
> \ /
> \ /
> --(A)---- ASIC --(B)--
> |
> (C)
> |
> CPU (SW stats are counted here)
>
>
> Now we have couple of flows for TX and RX (direction does not matter here):
>
> 1) port1->A->ASIC->C->CPU
>
> For this flow, HW and SW stats are equal.
>
> 2) port1->A->ASIC->C->CPU->C->ASIC->B->port2
>
> For this flow, HW and SW stats are equal.
>
> 3) port1->A->ASIC->B->port2
>
> For this flow, SW stats are 0.
>
> The purpose of this patchset is to provide facility for user to
> find out the difference between flows 1+2 and 3. In other words, user
> will be able to see the statistics for his slow-path (through kernel).
>
> Also, as a default the accumulated stats (HW) will be exposed to user
> so the userspace apps can react properly.
>

You no longer agree with this discussion?
http://comments.gmane.org/gmane.linux.network/346740

Essentially netdevice stats show counters for packets punted to the cpu
and ethool -S shows h/w stats. This patch set seems to invert that.