Hi, On 09/06/2015 07:15 PM, Tahhan, Maryam wrote: >> From: Andriy Berestovskyy [mailto:aber at semihalf.com] >> Sent: Friday, September 4, 2015 5:59 PM >> To: Tahhan, Maryam >> Cc: dev at dpdk.org; Olivier MATZ >> Subject: Re: ixgbe: account more Rx errors Issue >> >> Hi Maryam, >> Please see below. >> >>> XEC counts the Number of receive IPv4, TCP, UDP or SCTP XSUM errors >> >> Please note than UDP checksum is optional for IPv4, but UDP packets with >> zero checksum hit XEC. >> > > I understand, but this is what the hardware register is picking up and what I > included previously is the definitions of the registers from the datasheet. > >>> And general crc errors counts Counts the number of receive packets with >> CRC errors. >> >> Let me explain you with an example. >> >> DPDK 2.0 behavior: >> host A sends 10M IPv4 UDP packets (no checksum) to host B host B stats: 9M >> ipackets + 1M ierrors (missed) = 10M >> >> DPDK 2.1 behavior: >> host A sends 10M IPv4 UDP packets (no checksum) to host B host B stats: 9M >> ipackets + 11M in ierrors (1M missed + 10M XEC) = 20M? > > Because it's hitting the 2 error registers. If you had packets with multiple > errors that are added up as part of ierrors you'll still be getting more than > 10M errors which is why I asked for feedback on the 3 suggestions below. What > I'm saying is the number of errors being > the number of received packets > will be seen if you hit multiple error registers on the NIC. > >> >>> So our options are we can: >>> 1. Add only one of these into the error stats. >>> 2. We can introduce some cooking of stats in this scenario, so only add >> either or if they are equal or one is higher than the other. >>> 3. Add them all which means you can have more errors than the number of >> received packets, but TBH this is going to be the case if your packets have >> multiple errors anyway. >> >> 4. ierrors should reflect NIC drops only. > > I may have misinterpreted this, but ierrors in rte_ethdev.h ierrors is > defined as the Total number of erroneous received packets. > Maybe we need a clear definition or a separate drop counter as I see uint64_t > q_errors defined as: Total number of queue packets received that are dropped. > >> XEC does not count drops, so IMO it should be removed from ierrors. > > While it's picking up the 0 checksum as an error (which it shouldn't > necessarily be doing), removing it could mean missing other valid L3/L4 > checksum errors... Let me experiment some more with L3/L4 checksum errors and > crcerrs to see if we can cook the stats around this register in particular. I > would hate to remove it and miss genuine errors
For me, the definition that looks the most straightforward is: ipackets = packets successfully received by hardware imissed = packets dropped by hardware because the software does not poll fast enough (= queue full) ierrors = packets dropped by hardware (malformed packets, ...) These 3 stats never count twice the same packet. If we want more statistics, they could go in xstats. For instance, a counter for invalid checksum. The definition of these stats would be pmd-specific. I agree we should clarify and have a consensus on the definitions before going further. Regards, Olivier > >> >> Please note that we still can access the XEC using rte_eth_xstats_get() >> >> >> Regards, >> Andriy
