Re: [PATCH net-next 06/14] net: dev: Add hardware stats support

Jakub Kicinski [off-list ref] writes:

On Thu, 24 Feb 2022 15:33:27 +0200 Ido Schimmel wrote:

quoted

From: Petr Machata <petrm@nvidia.com>

Offloading switch device drivers may be able to collect statistics of the
traffic taking place in the HW datapath that pertains to a certain soft
netdevice, such as VLAN. Add the necessary infrastructure to allow exposing
these statistics to the offloaded netdevice in question. The API was shaped
by the following considerations:

- Collection of HW statistics is not free: there may be a finite number of
  counters, and the act of counting may have a performance impact. It is
  therefore necessary to allow toggling whether HW counting should be done
  for any particular SW netdevice.

- As the drivers are loaded and removed, a particular device may get
  offloaded and unoffloaded again. At the same time, the statistics values
  need to stay monotonous (modulo the eventual 64-bit wraparound),

monotonic

OK.

quoted

  increasing only to reflect traffic measured in the device.

quoted

+	struct rtnl_link_stats64 *offload_xstats_l3;

Does it make sense to stick to rtnl_link_stats64 for this?
There's a lot of.. historical baggage in that struct.

It seemed like a reasonable default that every tool already understands.

Was there a discussion in the past about what a cross-vendor stats suite
should look like? It seems like one of those things that can be bikeshed
forever...