The machine is no longer running, but I can run apport-collect from a
similar machine. The only difference being that we've since added a line
to our startup script to reduce the MTU to 1500.

** Tags added: apport-collected

** Description changed:

  Running Ubuntu 14.04 LTS on EC2, we see a lot of the following in the
  kernel log:
  
      xen_netfront: xennet: skb rides the rocket: 19 slots
  
  Each of these messages corresponds to a dropped TX packet, and
  eventually causes our application's connections to break and timeout.
  
  The problem appears when network load increases. We have Node.js
  processes doing pubsub with a Redis server, and these are most visibly
  affected, showing frequent connection loss. The processes talk to each
  other using the private addresses EC2 allocates to the machines.
  
  Notably, the default MTU on the network interface seems to have gone up
  from 1500 on 13.10, to 9000 in 14.04 LTS. Reducing the MTU back to 1500
  seems to drastically reduce dropped packets. (Can't say for certain if
  it completely eliminates the problem.)
  
  The machines we run are started from ami-896c96fe.
  
  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: linux-image-3.13.0-24-generic 3.13.0-24.46
  ProcVersionSignature: User Name 3.13.0-24.46-generic 3.13.9
  Uname: Linux 3.13.0-24-generic x86_64
  AlsaDevices:
   total 0
   crw-rw---- 1 root audio 116,  1 May  9 09:01 seq
   crw-rw---- 1 root audio 116, 33 May  9 09:01 timer
  AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
  ApportVersion: 2.14.1-0ubuntu3
  Architecture: amd64
  ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
  AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', 
'/dev/snd/timer'] failed with exit code 1:
  CRDA: Error: [Errno 2] No such file or directory: 'iw'
  Date: Fri May  9 09:11:18 2014
  Ec2AMI: ami-896c96fe
  Ec2AMIManifest: (unknown)
  Ec2AvailabilityZone: eu-west-1c
  Ec2InstanceType: c3.large
  Ec2Kernel: aki-52a34525
  Ec2Ramdisk: unavailable
  IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
  Lspci:
   
  Lsusb: Error: command ['lsusb'] failed with exit code 1: unable to initialize 
libusb: -99
  PciMultimedia:
   
  ProcFB:
   
  ProcKernelCmdLine: root=LABEL=cloudimg-rootfs ro console=hvc0
  RelatedPackageVersions:
   linux-restricted-modules-3.13.0-24-generic N/A
   linux-backports-modules-3.13.0-24-generic  N/A
   linux-firmware                             N/A
  RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
+ --- 
+ AlsaDevices:
+  total 0
+  crw-rw---- 1 root audio 116,  1 May  9 09:54 seq
+  crw-rw---- 1 root audio 116, 33 May  9 09:54 timer
+ AplayDevices: Error: [Errno 2] No such file or directory
+ ApportVersion: 2.14.1-0ubuntu3
+ Architecture: amd64
+ ArecordDevices: Error: [Errno 2] No such file or directory
+ AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', 
'/dev/snd/timer'] failed with exit code 1:
+ CRDA: Error: [Errno 2] No such file or directory
+ CurrentDmesg: [   24.724129] init: plymouth-upstart-bridge main process 
ended, respawning
+ DistroRelease: Ubuntu 14.04
+ Ec2AMI: ami-896c96fe
+ Ec2AMIManifest: (unknown)
+ Ec2AvailabilityZone: eu-west-1c
+ Ec2InstanceType: c3.large
+ Ec2Kernel: aki-52a34525
+ Ec2Ramdisk: unavailable
+ IwConfig: Error: [Errno 2] No such file or directory
+ Lspci:
+  
+ Lsusb: Error: command ['lsusb'] failed with exit code 1: unable to initialize 
libusb: -99
+ Package: linux (not installed)
+ PciMultimedia:
+  
+ ProcFB:
+  
+ ProcKernelCmdLine: root=LABEL=cloudimg-rootfs ro console=hvc0
+ ProcVersionSignature: User Name 3.13.0-24.46-generic 3.13.9
+ RelatedPackageVersions:
+  linux-restricted-modules-3.13.0-24-generic N/A
+  linux-backports-modules-3.13.0-24-generic  N/A
+  linux-firmware                             N/A
+ RfKill: Error: [Errno 2] No such file or directory
+ Tags:  trusty ec2-images
+ Uname: Linux 3.13.0-24-generic x86_64
+ UpgradeStatus: No upgrade log present (probably fresh install)
+ UserGroups: adm audio cdrom dialout dip floppy netdev plugdev sudo video
+ _MarkForUpload: True

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https://bugs.launchpad.net/bugs/1317811

Title:
  Dropped packets on EC2, "xen_netfront: xennet: skb rides the rocket: x
  slots"

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