Comment 0 for bug 1030516

I am wiping a SATA disk which is attached via USB in an enclosure. I'm running this command:-

root@deep-thought:~# dd if=/dev/zero bs=512M | pv -s 250059350016 -petr > /dev/sdb

Whilst running I note significant IO wait on all cores. This means the desktop becomes very slow and at times completely unresponsive. Applications go grey as they wait and sometimes the mouse cursor doesn't even move.

top - 14:55:26 up 21:31, 4 users, load average: 4.12, 3.80, 3.73
Tasks: 215 total, 2 running, 212 sleeping, 0 stopped, 1 zombie
Cpu0 : 21.8%us, 5.1%sy, 0.0%ni, 69.5%id, 2.5%wa, 0.0%hi, 1.1%si, 0.0%st
Cpu1 : 5.6%us, 5.2%sy, 0.0%ni, 89.2%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu2 : 23.3%us, 2.0%sy, 0.0%ni, 55.1%id, 19.3%wa, 0.0%hi, 0.3%si, 0.0%st
Cpu3 : 8.6%us, 3.3%sy, 0.0%ni, 16.6%id, 71.1%wa, 0.0%hi, 0.3%si, 0.0%st
Mem: 8058844k total, 7924184k used, 134660k free, 2157808k buffers
Swap: 8267772k total, 12164k used, 8255608k free, 2208596k cached

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image-3.2.0-27-generic 3.2.0-27.43
ProcVersionSignature: Ubuntu 3.2.0-27.43-generic 3.2.21
Uname: Linux 3.2.0-27-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu11
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: PCH [HDA Intel PCH], device 0: CONEXANT Analog [CONEXANT Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: alan 2296 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'PCH'/'HDA Intel PCH at 0xf2620000 irq 52'
   Mixer name : 'Intel CougarPoint HDMI'
   Components : 'HDA:14f1506e,17aa21da,00100002 HDA:80862805,80860101,00100000'
   Controls : 27
   Simple ctrls : 9
Card29.Amixer.info:
 Card hw:29 'ThinkPadEC'/'ThinkPad Console Audio Control at EC reg 0x30, fw unknown'
   Mixer name : 'ThinkPad EC (unknown)'
   Components : ''
   Controls : 1
   Simple ctrls : 1
Card29.Amixer.values:
 Simple mixer control 'Console',0
   Capabilities: pswitch pswitch-joined penum
   Playback channels: Mono
   Mono: Playback [on]
Date: Sun Jul 29 14:48:41 2012
EcryptfsInUse: Yes
HibernationDevice: RESUME=UUID=4de844e6-b3a9-4309-bc26-739bea6b4146
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
MachineType: LENOVO 4287CTO
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-27-generic root=UUID=c8438547-b9fb-46af-8012-4663c77c70e7 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.2.0-27-generic N/A
 linux-backports-modules-3.2.0-27-generic N/A
 linux-firmware 1.79
SourcePackage: linux
StagingDrivers: mei
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/15/2011
dmi.bios.vendor: LENOVO
dmi.bios.version: 8DET52WW (1.22 )
dmi.board.asset.tag: Not Available
dmi.board.name: 4287CTO
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr8DET52WW(1.22):bd09/15/2011:svnLENOVO:pn4287CTO:pvrThinkPadX220:rvnLENOVO:rn4287CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 4287CTO
dmi.product.version: ThinkPad X220
dmi.sys.vendor: LENOVO