Virtualization - Dec 2021 - [PATCH v2 net-next 00/26] net: introduce and use generic XDP stats

On 11/30/21 10:04 AM, Jakub Kicinski wrote:
> On Tue, 30 Nov 2021 17:34:54 +0100 Alexander Lobakin wrote:
>>> Another thought on this patch: with individual attributes you could
save
>>> some overhead by not sending 0 counters to userspace. e.g., define
a
>>> helper that does:  
>>
>> I know about ETHTOOL_STAT_NOT_SET, but RTNL xstats doesn't use
this,
>> does it?
> 
> Not sure if you're asking me or Dave but no, to my knowledge RTNL does
> not use such semantics today. But the reason is mostly because there
> weren't many driver stats added there. Knowing if an error counter is
> not supported or supporter and 0 is important for monitoring. Even if
> XDP stats don't have a counter which may not be supported today
it's
> not a good precedent to make IMO.
> 
Today, stats are sent as a struct so skipping stats whose value is 0 is
not an option. When using individual attributes for the counters this
becomes an option. Given there is no value in sending '0' why do it?

Is your pushback that there should be a uapi to opt-in to this behavior?

On 2021-11-30 12:38, David Ahern wrote:
> Today, stats are sent as a struct so skipping stats whose value is 0 is
> not an option. When using individual attributes for the counters this
> becomes an option. Given there is no value in sending '0' why do
it?
> 
> Is your pushback that there should be a uapi to opt-in to this behavior?
A filter in the netlink request should help pick what is user-preferred.
You can default to not sending zeros.

cheers,
jamal