[Bug 997695] Re: severe performance issue using mdadm raid5 on top of LUKS

Sven Reinecke sreinecke at reinsn.de
Wed Sep 26 21:11:09 UTC 2012


I am having a similar issue using Ubuntu 12.04 x86_64.

mdadm RAID5, 3x 2TB Hard drives.

dm-crypt on /dev/md0 (aes-xts-plain -s 256, but cipher does NOT matter)

System performance is very bad on 12.04:

root at chimera:~# time sh -c "dd if=/dev/zero of=/dev/mapper/md0_crypt bs=8k count=2000000 && sync"
2000000+0 Datensätze ein
2000000+0 Datensätze aus
16384000000 Bytes (16 GB) kopiert, 271,431 s, 60,4 MB/s

real	4m31.558s
user	0m0.352s
sys	0m11.829s

On 10.04 bootet from flash drive:

root at ubuntu:~# time sh -c "dd if=/dev/zero of=/dev/mapper/md0_crypt bs=8k count=2000000 && sync"
2000000+0 Datensätze ein
2000000+0 Datensätze aus
16384000000 Bytes (16 GB) kopiert, 178.911 s, 91.6 MB/s

real	2m59.269s
user	0m0.290s
sys	0m11.680s

System load on 12.04 goes up to 10,  on 10.04 it is only ~1.

This is "top" while dd'ing on 12.04:

top - 20:53:42 up 14:06,  3 users,  load average: 4.63, 2.62, 1.67
Tasks: 119 total,   2 running, 117 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.0%us, 20.6%sy,  0.0%ni, 59.9%id, 19.3%wa,  0.0%hi,  0.2%si,  0.0%st
Mem:   8087012k total,  7873560k used,   213452k free,  7297544k buffers
Swap:  8298492k total,        0k used,  8298492k free,    99324k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND            
 5137 root      20   0     0    0    0 D   21  0.0   0:21.24 kworker/3:1        
 2126 root      20   0     0    0    0 R   21  0.0   0:34.29 kworker/1:2        
 5140 root      20   0     0    0    0 D   18  0.0   0:03.54 kworker/2:3        
 2912 root      20   0     0    0    0 D   17  0.0   0:55.45 kworker/0:1        
 2436 root      20   0     0    0    0 S   12  0.0  69:22.81 md0_raid5          
 5134 root      20   0 12912  664  544 D    4  0.0   0:09.65 dd                 
   35 root      20   0     0    0    0 S    1  0.0   0:02.37 kswapd0            
  718 root      20   0     0    0    0 S    0  0.0   0:05.05 kworker/3:2        
 4585 root      20   0     0    0    0 S    0  0.0   0:48.45 kworker/2:2        
 5135 root      20   0     0    0    0 S    0  0.0   0:04.76 flush-252:0        
 5138 root      20   0     0    0    0 S    0  0.0   0:00.50 kworker/1:1        
 5339 root      20   0 17332 1292  960 R    0  0.0   0:00.02 top                
    1 root      20   0 24324 2300 1372 S    0  0.0   0:00.80 init               
    2 root      20   0     0    0    0 S    0  0.0   0:00.00 kthreadd           
    3 root      20   0     0    0    0 S    0  0.0   0:00.21 ksoftirqd/0        
    6 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/0        
    7 root      RT   0     0    0    0 S    0  0.0   0:00.10 watchdog/0    

Please just tell me what further information you need.

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Title:
  severe performance issue using mdadm raid5 on top of LUKS

Status in “cryptsetup” package in Ubuntu:
  Invalid
Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  I've upgraded to 12.04 a few days ago and since this, the performance
  of my crypto-drive is limited by CPU.

  I'm running an MDADM RAID5 on top of 7 independendtly encrypted drives
  (Seagate Barracuda XT 7200.12 2TB each encrypted using crypsetup /
  LUKS).

  The problem seems to be, that in 12.04 all encryption is done using
  only a single CPU core. In 10.04 each crypt-device used its own thread
  (kcrypt), that was the reason to encrypt each device independently and
  build a raid on top of the crypto devices.

  I'll attach a screenshot of munins iostat and CPU graph to illustrate the difference before and after the upgrade
  --- 
  AlsaDevices:
   total 0
   crw-rw---T 1 root audio 116,  1 Mai  1 15:52 seq
   crw-rw---T 1 root audio 116, 33 Mai  1 15:52 timer
  AplayDevices: aplay: device_list:252: no soundcards found...
  ApportVersion: 2.0.1-0ubuntu7
  Architecture: amd64
  ArecordDevices: arecord: device_list:252: no soundcards found...
  AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
  CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
  DistroRelease: Ubuntu 12.04
  HibernationDevice: RESUME=
  IwConfig:
   lo        no wireless extensions.
   
   virbr0    no wireless extensions.
   
   eth0      no wireless extensions.
  Lsusb:
   Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
   Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
   Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 004 Device 002: ID 051d:0002 American Power Conversion Uninterruptible Power Supply
  MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M.
  Package: linux (not installed)
  ProcEnviron:
   LANGUAGE=de_DE:de:en_US:en
   TERM=xterm
   LANG=de_DE.UTF-8
   SHELL=/bin/bash
  ProcFB: 0 nouveaufb
  ProcKernelCmdLine: root=/dev/mapper/md1_crypt ro quiet splash
  ProcVersionSignature: Ubuntu 3.2.0-24.37-generic 3.2.14
  RelatedPackageVersions:
   linux-restricted-modules-3.2.0-24-generic N/A
   linux-backports-modules-3.2.0-24-generic  N/A
   linux-firmware                            1.79
  RfKill: Error: [Errno 2] No such file or directory
  StagingDrivers: cxd2099
  Tags:  precise staging
  Uname: Linux 3.2.0-24-generic x86_64
  UpgradeStatus: Upgraded to precise on 2012-04-30 (10 days ago)
  UserGroups: mythtv
  dmi.bios.date: 04/30/2010
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: P2.30
  dmi.board.name: K10N78FullHD-hSLI..
  dmi.board.vendor: ASRock
  dmi.chassis.asset.tag: To Be Filled By O.E.M.
  dmi.chassis.type: 3
  dmi.chassis.vendor: To Be Filled By O.E.M.
  dmi.chassis.version: To Be Filled By O.E.M.
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP2.30:bd04/30/2010:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rnK10N78FullHD-hSLI..:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
  dmi.product.name: To Be Filled By O.E.M.
  dmi.product.version: To Be Filled By O.E.M.
  dmi.sys.vendor: To Be Filled By O.E.M.

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