On Wed, 8 Sep 2021 18:26:35 +0300 Ilias Apalodimas wrote:
Normally I'd say put the stats in ethtool -S and the rest in debugfs but I'm not sure if exposing pages_state_hold_cnt and pages_state_release_cnt directly. Those are short counters, and will very likely wrap. They are primarily meaningful for calculating page_pool_inflight(). Given this I think their semantics may be too confusing for an average ethtool -S user.
Putting all the information in debugfs seems like a better idea.
I can't really disagree on the aforementioned stats being confusing. However at some point we'll want to add more useful page_pool stats (e.g the percentage of the page/page fragments that are hitting the recycling path). Would it still be 'ok' to have info split across ethtool and debugfs?
Possibly. We'll also see what Alex L comes up with for XDP stats. Maybe we can arrive at a netlink API for standard things (broken record).
You said percentage - even tho I personally don't like it - there is a small precedent of ethtool -S containing non-counter information (IOW not monotonically increasing event counters), e.g. some vendors rammed PCI link quality in there. So if all else fails ethtool -S should be fine.