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

On 06/17/2016 08:42 AM, Jiri Pirko wrote:

Fri, Jun 17, 2016 at 05:35:53PM CEST, dsa@cumulusnetworks.com wrote:

quoted

On 6/17/16 8:54 AM, Jamal Hadi Salim wrote:

quoted

On 16-06-17 10:05 AM, Jiri Pirko wrote:

quoted

Fri, Jun 17, 2016 at 03:48:35PM CEST, dsa@cumulusnetworks.com wrote:

quoted

On 6/17/16 2:24 AM, Jiri Pirko wrote:

quoted

quoted

That is problematic. Existing apps depend on rtnetlink stats. But if we
don't count offloaded forwarded packets, the apps don't see anything.
Therefore I believe that this patchset approach is better. The existing
apps continue to work and future apps can use newly introduces sw_stats
to query slowpath traffic. Makes sense to me.

I agree with Jiri. It is a bad idea to depend on ethtool for any of
this stuff. Is there a way we can tag netlink stats instead
to indicate they are hardware or software?

Right, old API but the key here is that low level h/w stats are returned by a
different API.

By default ip, ifconfig, snmpd, etc all continue to get traditional S/W stats
- counters as seen by the CPU.

Yep. And I believe that for offloaded forwarding, this tools should see
hw counters, as they show what is going on in real.

If your NIC is offloading packets today, these tools typically won't see
these stats, but ethtool -S likely will report what is going on under
the hood.

Do we actually need to tell apart SW maintained from HW maintained
stats, or at the end all that matters is just, as DaveM pointed out,
getting the information, and in the case of an Ethernet switch, return
HW stats by default and supplement with SW stats whenever we have them,
all in the same namespace?
-- 
Florian