Seeking help understanding my "emX: watchdog timeout" messages

[Rudy]

I am getting these messages:
  Jun 17 08:53:14 example kernel: em2: watchdog timeout -- resetting
  Jun 17 08:53:14 example kernel: em2: link state changed to DOWN
  Jun 17 08:53:17 example kernel: em2: link state changed to UP
  Jun 17 11:07:38 example kernel: em2: watchdog timeout -- resetting
  Jun 17 11:07:38 example kernel: em2: link state changed to DOWN
  Jun 17 11:07:41 example kernel: em2: link state changed to UP
on an interface that does about 100Mbps all day.

[1] should I worry about it (only happens a couple of times a day)?
[2] will setting  dev.em.2.rx_int_delay help?
     couldn't find too much documentation on it...  Best I could get:
     http://www.intel.com/support/network/sb/cs-009209.htm
[3] what, in you best estimation, is causing these wathdog events?


sysctl dev.em.2.stats=1
  Jun 17 13:23:22 example kernel: em2: Excessive collisions = 0
  Jun 17 13:23:22 example kernel: em2: Sequence errors = 0
  Jun 17 13:23:22 example kernel: em2: Defer count = 0
  Jun 17 13:23:22 example kernel: em2: Missed Packets = 81518
  Jun 17 13:23:22 example kernel: em2: Receive No Buffers = 1226
  Jun 17 13:23:22 example kernel: em2: Receive Length Errors = 0
  Jun 17 13:23:22 example kernel: em2: Receive errors = 0
  Jun 17 13:23:22 example kernel: em2: Crc errors = 0
  Jun 17 13:23:22 example kernel: em2: Alignment errors = 0
  Jun 17 13:23:22 example kernel: em2: Collision/Carrier extension errors = 0
  Jun 17 13:23:22 example kernel: em2: RX overruns = 0
  Jun 17 13:23:22 example kernel: em2: watchdog timeouts = 20
  Jun 17 13:23:22 example kernel: em2: RX MSIX IRQ = 0 TX MSIX IRQ = 0 LINK MSIX IRQ = 0
  Jun 17 13:23:22 example kernel: em2: XON Rcvd = 0
  Jun 17 13:23:22 example kernel: em2: XON Xmtd = 0
  Jun 17 13:23:22 example kernel: em2: XOFF Rcvd = 0
  Jun 17 13:23:22 example kernel: em2: XOFF Xmtd = 0
  Jun 17 13:23:22 example kernel: em2: Good Packets Rcvd = 2515504832
  Jun 17 13:23:22 example kernel: em2: Good Packets Xmtd = 4543057019
  Jun 17 13:23:22 example kernel: em2: TSO Contexts Xmtd = 8
  Jun 17 13:23:22 example kernel: em2: TSO Contexts Failed = 0

sysctl dev.em.2.debug=1
  Jun 17 13:28:48 example kernel: em2: Adapter hardware address = 0xc4d91224
  Jun 17 13:28:48 example kernel: em2: CTRL = 0x400c0241 RCTL = 0x8002
  Jun 17 13:28:48 example kernel: em2: Packet buffer = Tx=16k Rx=32k
  Jun 17 13:28:48 example kernel: em2: Flow control watermarks high = 30720 low = 29220
  Jun 17 13:28:48 example kernel: em2: tx_int_delay = 66, tx_abs_int_delay = 66
  Jun 17 13:28:48 example kernel: em2: rx_int_delay = 0, rx_abs_int_delay = 66
  Jun 17 13:28:48 example kernel: em2: fifo workaround = 0, fifo_reset_count = 0
  Jun 17 13:28:48 example kernel: em2: hw tdh = 116, hw tdt = 116
  Jun 17 13:28:48 example kernel: em2: hw rdh = 175, hw rdt = 174
  Jun 17 13:28:48 example kernel: em2: Num Tx descriptors avail = 256
  Jun 17 13:28:48 example kernel: em2: Tx Descriptors not avail1 = 20
  Jun 17 13:28:48 example kernel: em2: Tx Descriptors not avail2 = 0
  Jun 17 13:28:48 example kernel: em2: Std mbuf failed = 0
  Jun 17 13:28:48 example kernel: em2: Std mbuf cluster failed = 0
  Jun 17 13:28:48 example kernel: em2: Driver dropped packets = 0
  Jun 17 13:28:48 example kernel: em2: Driver tx dma failure in encap = 0


sysctl dev.em.2
dev.em.2.%desc: Intel(R) PRO/1000 Network Connection 6.9.5
dev.em.2.%driver: em
dev.em.2.%location: slot=0 function=0
dev.em.2.%pnpinfo: vendor=0x8086 device=0x10a4 subvendor=0x8086 subdevice=0x10a4 class=0x020000
dev.em.2.%parent: pci6
dev.em.2.debug: -1
dev.em.2.stats: -1
dev.em.2.rx_int_delay: 0
dev.em.2.tx_int_delay: 66
dev.em.2.rx_abs_int_delay: 66
dev.em.2.tx_abs_int_delay: 66
dev.em.2.rx_processing_limit: 100

Polling related sysctl settings:
kern.polling.idlepoll_sleeping: 1
kern.polling.stalled: 82
kern.polling.suspect: 6266
kern.polling.phase: 0
kern.polling.enable: 1
kern.polling.handlers: 6
kern.polling.residual_burst: 0
kern.polling.pending_polls: 1
kern.polling.lost_polls: 371823
kern.polling.short_ticks: 4795
kern.polling.reg_frac: 20
kern.polling.user_frac: 33
kern.polling.idle_poll: 0
kern.polling.each_burst: 5
kern.polling.burst_max: 350
kern.polling.burst: 350
kern.clockrate: { hz = 2500, tick = 400, profhz = 1666, stathz = 333 }

hadware is a quad Intel 1000 Pro PT card.

Thanks!!!!

Rudy