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[Valerio <valerio.morettini@xxxxxxxxx>]

apport information

** Attachment added: "BootDmesg.txt"
   https://bugs.launchpad.net/bugs/1538040/+attachment/4590959/+files/BootDmesg.txt

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https://bugs.launchpad.net/bugs/1538040

Title:
  Internal Hard drive extremely slow unless using barrier=0 on ext4

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  I have a brand new laptop (Asus N551VW, i7-6700HQ, 16 Gb ram) on which
  i installed Ubuntu 14.04 64bit and a new Samsung SSD 850 PRO 512Gb
  (latest firmware). I installed the default MySql 5.6.27 on the machine
  but I noticed a very VERY slow performance of the database (just
  creating a db and executing some migrations without any data takes
  around 33 seconds while on lower-hardware co-workers notebooks it
  takes like 3 seconds). Every sql statement seems to spend most time in
  "system lock" state, as i could see with a SHOW PROCESSLIST.

  I thought it to be an hard drive issue, but executing the hard drive
  benchmark in Ubuntu gives 500 Mb/s read and 350 Mb/s write speed,
  which looks mostly normal.

  I also tried updating to the new 4.2 kernel, but the issue still
  there. To make an experiment, i cloned the ssd on a normal hard drive,
  switched it in and connected the SSD externally with an usb box. I
  moved mysql data directory to the external disk, and retried the db
  creation: it took only 2.5 seconds.

  Just out of curiosity i tried the same operation on an internal non-
  ssd disk: when the hd is plugged inside the laptop with sata, the
  database creation takes more than 2 minutes, while with the data dir
  on external usb (with the same physical disk) it took less than 10
  seconds.

  To make it short, after some research, adding barrier=0 to the mount
  options of the root drive with no other modification caused the same
  script to take 1.5 seconds instead of 33, with a 22x increase in
  performance.

  I have opened his bug on askubuntu (http://askubuntu.com/questions/725182/ssd-extremely-slow-when-connected-with-internal-sata-ok-with-external-usb ) and it was suggested that this coud be an issue of the controller firmware/driver.
  The problem is present both in trusty's default kernel (3.19.0-47.53) and in the 4.2 (4.2.0-25.30).

  Let me know if you need more informations!

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: linux-image-4.2.0-25-generic 4.2.0-25.30~14.04.1
  ProcVersionSignature: Ubuntu 4.2.0-25.30~14.04.1-generic 4.2.6
  Uname: Linux 4.2.0-25-generic x86_64
  NonfreeKernelModules: nvidia
  ApportVersion: 2.14.1-0ubuntu3.19
  Architecture: amd64
  Date: Tue Jan 26 09:25:04 2016
  InstallationDate: Installed on 2016-01-06 (19 days ago)
  InstallationMedia: Ubuntu 14.04.3 LTS "Trusty Tahr" - Beta amd64 (20150805)
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: linux-lts-wily
  UpgradeStatus: No upgrade log present (probably fresh install)
  --- 
  ApportVersion: 2.14.1-0ubuntu3.19
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  valerio    2776 F.... pulseaudio
  DistroRelease: Ubuntu 14.04
  HibernationDevice: RESUME=UUID=e5eee076-9bfc-4547-bf85-0208b98b57a8
  InstallationDate: Installed on 2016-01-06 (60 days ago)
  InstallationMedia: Ubuntu 14.04.3 LTS "Trusty Tahr" - Beta amd64 (20150805)
  Lsusb:
   Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
   Bus 001 Device 003: ID 8087:0a2a Intel Corp. 
   Bus 001 Device 002: ID 04f2:b3fd Chicony Electronics Co., Ltd 
   Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
  MachineType: ASUSTeK COMPUTER INC. N551VW
  NonfreeKernelModules: nvidia
  Package: linux (not installed)
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-30-generic root=UUID=5231fd09-180d-4fd2-bad5-e989207b11e7 ro quiet splash elevator=deadline vt.handoff=7
  ProcVersionSignature: Ubuntu 4.2.0-30.36~14.04.1-generic 4.2.8-ckt3
  PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
  RelatedPackageVersions:
   linux-restricted-modules-4.2.0-30-generic N/A
   linux-backports-modules-4.2.0-30-generic  N/A
   linux-firmware                            1.127.20
  Tags:  trusty
  Uname: Linux 4.2.0-30-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups:
   
  _MarkForUpload: True
  dmi.bios.date: 11/13/2015
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: N551VW.205
  dmi.board.asset.tag: ATN12345678901234567
  dmi.board.name: N551VW
  dmi.board.vendor: ASUSTeK COMPUTER INC.
  dmi.board.version: 1.0
  dmi.chassis.asset.tag: ATN12345678901234567
  dmi.chassis.type: 10
  dmi.chassis.vendor: ASUSTeK COMPUTER INC.
  dmi.chassis.version: 1.0
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrN551VW.205:bd11/13/2015:svnASUSTeKCOMPUTERINC.:pnN551VW:pvr1.0:rvnASUSTeKCOMPUTERINC.:rnN551VW:rvr1.0:cvnASUSTeKCOMPUTERINC.:ct10:cvr1.0:
  dmi.product.name: N551VW
  dmi.product.version: 1.0
  dmi.sys.vendor: ASUSTeK COMPUTER INC.

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