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Date: Thu, 08 Sep 2016 19:21:30 -0700
From: Roopa Prabhu <roopa@...ulusnetworks.com>
To: Jiri Pirko <jiri@...nulli.us>
CC: netdev@...r.kernel.org, davem@...emloft.net, nogahf@...lanox.com,
idosch@...lanox.com, eladr@...lanox.com, yotamg@...lanox.com,
ogerlitz@...lanox.com, nikolay@...ulusnetworks.com,
linville@...driver.com, tgraf@...g.ch, gospo@...ulusnetworks.com,
sfeldma@...il.com, sd@...asysnail.net, eranbe@...lanox.com,
ast@...mgrid.com, edumazet@...gle.com, hannes@...essinduktion.org,
f.fainelli@...il.com, dsa@...ulusnetworks.com
Subject: Re: [patch net-next v8 0/3] return offloaded stats as default and
expose original sw stats
On 9/7/16, 11:19 PM, Jiri Pirko wrote:
> From: Jiri Pirko <jiri@...lanox.com>
>
> 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 <roopa@...ulusnetworks.com>
thanks.
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