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Date:      Thu, 9 Feb 2012 00:15:18 +0000
From:      "Vogel, Jack" <jack.vogel@intel.com>
To:        Arnaud Lacombe <lacombar@gmail.com>
Cc:        "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>
Subject:   RE: Missed packet on recent em(4)
Message-ID:  <BC1B13FD0226B0479C795193AC1B25720445A7@ORSMSX104.amr.corp.intel.com>
In-Reply-To: <CACqU3MWLcURFL4k3-Athcvd5TwtodqA5=vryE-wxgFFp8-wnrw@mail.gmail.com>
References:  <CACqU3MWLcURFL4k3-Athcvd5TwtodqA5=vryE-wxgFFp8-wnrw@mail.gmail.com>

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The NETMAP code is all self-contained, just delete what's inside the ifdef'=
s=20

Jack


-----Original Message-----
From: Arnaud Lacombe [mailto:lacombar@gmail.com]=20
Sent: Wednesday, February 08, 2012 3:25 PM
To: Vogel, Jack
Cc: freebsd-net@freebsd.org
Subject: Missed packet on recent em(4)

Hi Jack,

For the record, on the following hardware:

em3@pci0:5:0:0: class=3D0x020000 card=3D0x150415bb chip=3D0x150c8086 rev=3D=
0x00 hdr=3D0x00

and the following version of em(4):

em3: <Intel(R) PRO/1000 Network Connection 7.2.3> port 0xec00-0xec1f
mem 0xfebe0000-0xfebfffff,0xfebdc000-0xfebdffff irq 19 at device 0.0
on pci5
em3: Using an MSI interrupt
em3: [FILTER]
em3: Ethernet address: 00:90:fb:35:18:b1

backported to 7-STABLE, I am still getting `missed_packets' increment,
without any obvious mbuf allocation denial. These increments do not
translate into complete hang of the driver, just crazy frame loss.

# sysctl dev.em.3
dev.em.3.%desc: Intel(R) PRO/1000 Network Connection 7.2.3
dev.em.3.%driver: em
dev.em.3.%location: slot=3D0 function=3D0
dev.em.3.%pnpinfo: vendor=3D0x8086 device=3D0x150c subvendor=3D0x15bb
subdevice=3D0x1504 class=3D0x020000
dev.em.3.%parent: pci5
dev.em.3.rx_int_delay: 0
dev.em.3.tx_int_delay: 66
dev.em.3.rx_abs_int_delay: 66
dev.em.3.tx_abs_int_delay: 66
dev.em.3.rx_processing_limit: 100
dev.em.3.flow_control: 3
dev.em.3.eee_control: 0
dev.em.3.link_irq: 0
dev.em.3.mbuf_alloc_fail: 0
dev.em.3.cluster_alloc_fail: 0
dev.em.3.dropped: 0
dev.em.3.tx_dma_fail: 0
dev.em.3.rx_overruns: 78
dev.em.3.watchdog_timeouts: 0
dev.em.3.device_control: 1477444168
dev.em.3.rx_control: 67141634
dev.em.3.fc_high_water: 18432
dev.em.3.fc_low_water: 16932
dev.em.3.queue0.txd_head: 703
dev.em.3.queue0.txd_tail: 703
dev.em.3.queue0.tx_irq: 0
dev.em.3.queue0.no_desc_avail: 0
dev.em.3.queue0.rxd_head: 692
dev.em.3.queue0.rxd_tail: 691
dev.em.3.queue0.rx_irq: 0
dev.em.3.mac_stats.excess_coll: 0
dev.em.3.mac_stats.single_coll: 0
dev.em.3.mac_stats.multiple_coll: 0
dev.em.3.mac_stats.late_coll: 0
dev.em.3.mac_stats.collision_count: 0
dev.em.3.mac_stats.symbol_errors: 0
dev.em.3.mac_stats.sequence_errors: 0
dev.em.3.mac_stats.defer_count: 0
dev.em.3.mac_stats.missed_packets: 1135790
dev.em.3.mac_stats.recv_no_buff: 555763
dev.em.3.mac_stats.recv_undersize: 0
dev.em.3.mac_stats.recv_fragmented: 0
dev.em.3.mac_stats.recv_oversize: 0
dev.em.3.mac_stats.recv_jabber: 0
dev.em.3.mac_stats.recv_errs: 0
dev.em.3.mac_stats.crc_errs: 0
dev.em.3.mac_stats.alignment_errs: 0
dev.em.3.mac_stats.coll_ext_errs: 0
dev.em.3.mac_stats.xon_recvd: 6806
dev.em.3.mac_stats.xon_txd: 253
dev.em.3.mac_stats.xoff_recvd: 7583
dev.em.3.mac_stats.xoff_txd: 742908
dev.em.3.mac_stats.total_pkts_recvd: 3904354
dev.em.3.mac_stats.good_pkts_recvd: 2761900
[...]

This happened with about 1000 short-lived TCP connection filling about
100Mbps of traffic.

I saw you made updates to the driver recently. I'll attempt a backport
and let you know. This might not be trivial given the netmap mess
which appeared in -current...

 - Arnaud



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