Messages in this thread | | | Date | Thu, 3 Feb 2022 11:34:26 -0800 | From | Jakub Kicinski <> | Subject | Re: [PATCH v6 net-next] net-core: add InMacErrors counter |
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On Thu, 3 Feb 2022 10:13:59 -0800 Eric Dumazet wrote: > > I had another thing and this still doesn't sit completely well > > with me :( > > > > Shouldn't we count those drops as skb->dev->rx_dropped? > > Commonly NICs will do such filtering and if I got it right > > in struct rtnl_link_stats64 kdoc - report them as rx_dropped. > > It'd be inconsistent if on a physical interface we count > > these as rx_dropped and on SW interface (or with promisc enabled > > etc.) in the SNMP counters. > > I like to see skb->dev->rx_dropped as a fallback-catch-all bucket > for all cases we do not already have a more specific counter.
Indeed, it's a fallback so counting relatively common events like unicast filtering into generic "drops" feels wrong. I heard complaints that this is non-intuitive and makes debug harder in the past.
> > Or we can add a new link stat that NICs can use as well. > > Yes, this could be done, but we have to be careful about not hitting > a single cache line, for the cases we receive floods of such messages > on multiqueue NIC. > (The single atomic in dev->rx_dropped) is suffering from this issue btw)
Even more of a reason to bite the bullet and move from the atomic counters to pcpu stats?
> > In fact I'm not sure this is really a IP AKA L3 statistic, > > it's the L2 address that doesn't match. > > > > > > If everyone disagrees - should we at least rename the MIB counter > > similarly to the drop reason? Experience shows that users call for > > help when they see counters with Error in their name, I'd vote for > > IpExtInDropOtherhost or some such. The statistic should also be > > documented in Documentation/networking/snmp_counter.rst
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