Re: [RFC net-next] net: mvneta: align xdp stats naming scheme to mlx5 driver

From: Toke Høiland-Jørgensen <redacted>
Date: Tue, 18 Feb 2020 23:23:22 +0100

Jakub Kicinski [off-list ref] writes:

quoted

On Tue, 18 Feb 2020 01:14:29 +0100 Lorenzo Bianconi wrote:

quoted

Introduce "rx" prefix in the name scheme for xdp counters
on rx path.
Differentiate between XDP_TX and ndo_xdp_xmit counters

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>

Sorry for coming in late.

I thought the ability to attach a BPF program to a fexit of another BPF
program will put an end to these unnecessary statistics. IOW I maintain
my position that there should be no ethtool stats for XDP.

As discussed before real life BPF progs will maintain their own stats
at the granularity of their choosing, so we're just wasting datapath
cycles.

The previous argument that the BPF prog stats are out of admin control
is no longer true with the fexit option (IIUC how that works).

So you're proposing an admin that wants to keep track of XDP has to
(permantently?) attach an fexit program to every running XDP program and
use that to keep statistics? But presumably he'd first need to discover
that XDP is enabled; which the ethtool stats is a good hint for :)

Really, mistakes happen and a poorly implemented or inserted fexit
module should not be a reason to not have access to accurate and
working statistics for fundamental events.

I am therefore totally against requiring fexit for this functionality.
If you want more sophisticated events or custome ones, sure, but not
for this baseline stuff.

I do, however, think we need a way to turn off these counter bumps if
the user wishes to do so for maximum performance.