Date: Thu, 2 Jun 2016 14:41:04 -0700 From: hiren panchasara <hiren@strugglingcoder.info> To: Sreekanth Rupavatharam <rupavath@juniper.net> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>, "jfvogel@gmail.com" <jfvogel@gmail.com>, sbruno@FreeBSD.org, erj@FreeBSD.org Subject: Re: Possible transmit/stats problem in igb driver. Message-ID: <20160602214104.GJ8994@strugglingcoder.info> In-Reply-To: <9A903EE5-3F2C-46C0-B563-1150F81E3507@juniper.net> References: <D7944476-98AD-4548-99E3-6E88648E2B06@juniper.net> <20160602202015.GG8994@strugglingcoder.info> <9A903EE5-3F2C-46C0-B563-1150F81E3507@juniper.net>
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[-- Attachment #1 --] + Sean, Eric On 06/02/16 at 09:11P, Sreekanth Rupavatharam 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. > Very interesting. Do you tune defaults at all? What does sysctl hw.igb say? Not sure if bumping up txd would help. Adding Sean and Eric to throw some light. > > 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 > Cheers, Hiren [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQF8BAABCgBmBQJXUKfrXxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXRBNEUyMEZBMUQ4Nzg4RjNGMTdFNjZGMDI4 QjkyNTBFMTU2M0VERkU1AAoJEIuSUOFWPt/ldLEIAKglyJHw+IRINg021FAF+3QN t5gjEuMkM4I3C/4VK25+BTouaOX3BZI/c6XGCL+uXSC+8HVKLZir7MQ0RRL6lq9H 3DGEP/qUZ7i3VOTA9IHXCc3HaLhuQ4Zs4x8sNw2YNhI29U6SS+IXSs+TiScisuHe ErfBLD7QEI9mq+JJoYLZdsHUosjVB7F/x9pJEddp0q63et2E5Hidu4xocW7JMIyI cvYYK0qEHn6k5hNNr9EjC0o2nvb3V5Z1q5pVdZppsmuSROtxU9FgtuT5LqMXuMMj FNGxPT6hIN8n7c2YXkjbfGpuVT7z1nT+80mQjiwSiykPYGL50IrKVKFZXuesNdU= =bO6U -----END PGP SIGNATURE-----
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