Subject: Re: [patch net-next v7 0/3] return offloaded stats as default and expose original sw stats

From: Roopa Prabhu <[email-masked]>
Date: Tue, 06 Sep 2016 07:59:19 -0700

On 9/5/16, 10:18 AM, Jiri Pirko wrote:
> From: Jiri Pirko <[email-masked]>
>
> The problem we try to handle is 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 the slow-path (through kernel).
>
> Also note that HW stats are what someone calls "accumulated" stats.
> Every packet counted by SW is also counted by HW. Not the other way around.
>
> As a default the accumulated stats (HW) will be exposed to user
> so the userspace apps can react properly.
>
> This patchset add the SW stats (flows 1+2) under offload related stats, so
> in the future we can expose other offload related stat in a similar way.
>
> ---
>
Acked-by: Roopa Prabhu <[email-masked]>
few questions on the two ndo's on specific patches, but, the user api LGTM.

thanks jiri and nogah.