Possible transmit/stats problem in igb driver.

[Jack Vogel]

Hmmm, so I no longer have access to any of this, but I'm wondering if there
is some
other stat that might report errors or some sort that would match the
missing/bad packets?

Maybe they were considered runts or something and dropped.

Good luck :)

Jack


On Thu, Jun 2, 2016 at 2:11 PM, Sreekanth Rupavatharam <rupavath at juniper.net
> wrote:

> Inline
>
> >Apart from stats, do you see anything else going wrong? i.e. do you
> >actually see less packets (arp replies??) than expected?
>
> [SR] The packets are not going out on the wire. The tool doesn’t receive
> the packets. That’s how I started noticing the issue.
>
> >Taking your example, tx_packets is something we count in the drivers and
> >total_pkts_txd is calculated in the card and we just read it off of it
> >to report (E1000_TPT).
>
> [SR] Correct. My main question would be under what circumstance would the
> packet handed off to hardware will *not* be transmitted?. Especially
> considering there are no transmit errors or pause frames received. There
> are no dma tx failures either. That’s the baffling part. I tried another
> exercise where I used ping of various sizes going out, but that doesn’t
> seem to trigger the problem.
>
>
> >To understand your setup better, ixia is the sender and your box with
> >igb(4) is the receiver and your are sending arp requests to it.
>
> Yes, correct.
>
> >Can you post following for working (size <= 64bytes) and non-working
> >(size > 64bytes) cases for before/after?
> >
> >sysctl dev.igb | grep tx_packets
> >sysctl dev.igb | grep total_pkts_txd
> >sysctl dev.igb | grep rx_packets
> >sysctl dev.igb | grep total_pkts_recvd
>
>
> Before(not working):
> dev.igb.1.queue0.tx_packets: 24907933
> dev.igb.1.queue0.rx_packets: 18086575
> dev.igb.1.mac_stats.total_pkts_recvd: 25057359
> dev.igb.1.mac_stats.total_pkts_txd: 16647169
>
> After(not working):
> dev.igb.1.queue0.tx_packets: 24913324
> dev.igb.1.queue0.rx_packets: 18091832
> dev.igb.1.mac_stats.total_pkts_recvd: 25062618
> dev.igb.1.mac_stats.total_pkts_txd: 16647545
> >netstat -sp arp
>
> The difference is  5391 for queue0.tx_packets but for
> mac_stats.total_pkts_txd  is 376
> Everything else is matching up.
>
> Before (working)
> dev.igb.1.queue0.tx_packets: 25359165
> dev.igb.1.queue0.rx_packets: 18526094
> dev.igb.1.mac_stats.total_pkts_recvd: 25508763
> dev.igb.1.mac_stats.total_pkts_txd: 16831587
>
>
> After(working)
> dev.igb.1.queue0.tx_packets: 25364597
> dev.igb.1.queue0.rx_packets: 18531398
> dev.igb.1.mac_stats.total_pkts_recvd: 25514009
> dev.igb.1.mac_stats.total_pkts_txd: 16836833
>
>
> Another interesting stat is
> before_notworking:dev.igb.1.interrupts.tx_queue_empty: 16646890
> after_notworking:dev.igb.1.interrupts.tx_queue_empty: 16647266
>
> The difference here is exactly 376 which is the number of packets that the
> device actually claims to have transmitted. It’s as though it didn’t see
> the other packets en-queued in the ring descriptor.
>
>
> I can’t do netstat just for arp as these are coming in a tunnel(Packets
> don’t’ show up as arp on the interface). However, I did see the packet rate
> was about 500 packets/sec
>
>
> >(You can netstat -z to clear the counters between runs.)
> >
> >Cheers,
> >Hiren
>
>