Virtualization - Nov 2021 - [PATCH net-next 03/21] ethtool, stats: introduce standard XDP statistics

Alexander Lobakin <alexandr.lobakin at intel.com> writes:
> From: Alexander Lobakin <alexandr.lobakin at intel.com>
> Date: Tue, 26 Oct 2021 11:23:23 +0200
>
>> From: Saeed Mahameed <saeed at kernel.org>
>> Date: Tue, 03 Aug 2021 16:57:22 -0700
>> 
>> [ snip ]
>> 
>> > XDP is going to always be eBPF based ! why not just report such
stats
>> > to a special BPF_MAP ? BPF stack can collect the stats from the
driver
>> > and report them to this special MAP upon user request.
>> 
>> I really dig this idea now. How do you see it?
>> <ifindex:channel:stat_id> as a key and its value as a value or
...?
>
> Ideas, suggestions, anyone?
I don't like the idea of putting statistics in a map instead of the
regular statistics counters. Sure, for bespoke things people want to put
into their XDP programs, use a map, but for regular packet/byte
counters, update the regular counters so XDP isn't "invisible".

As Jesper pointed out, batching the updates so the global counters are
only updated once per NAPI cycle is the way to avoid a huge performance
overhead of this...

-Toke