Messages in this thread | | | Date | Thu, 17 Mar 2022 09:49:13 -0600 | Subject | Re: [PATCH net-next v3 3/3] net: icmp: add reasons of the skb drops to icmp protocol | From | David Ahern <> |
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On 3/17/22 8:53 AM, David Laight wrote: > From: David Ahern >> Sent: 17 March 2022 14:49 >> >> On 3/16/22 10:05 PM, Jakub Kicinski wrote: >>> On Wed, 16 Mar 2022 21:35:47 -0600 David Ahern wrote: >>>> On 3/16/22 9:18 PM, Jakub Kicinski wrote: >>>>> >>>>> I guess this set raises the follow up question to Dave if adding >>>>> drop reasons to places with MIB exception stats means improving >>>>> the granularity or one MIB stat == one reason? >>>> >>>> There are a few examples where multiple MIB stats are bumped on a drop, >>>> but the reason code should always be set based on first failure. Did you >>>> mean something else with your question? >>> >>> I meant whether we want to differentiate between TYPE, and BROADCAST or >>> whatever other possible invalid protocol cases we can get here or just >>> dump them all into a single protocol error code. >> >> I think a single one is a good starting point. > > I remember looking at (I think) the packet drop stats a while back. > Two machines on the same LAN were reporting rather different values. > Basically 0 v quite a few. > > It turned out that passing the packets to dhcp was deemed enough > to stop them being reported as 'dropped'. > And I think that version of dhcp fed every packed into its BPF? filter. > (I never did decide whether that caused every skb to be duplicated.) >
I believe it depends on the type of socket. Packet sockets - e.g., running lldpd or tcpdump - do cause every packet to be cloned and kills performance.
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