** Changed in: linux (Ubuntu)
Importance: Low => Medium
** Changed in: linux (Ubuntu)
Status: Confirmed => Triaged
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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:
Triaged
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.
WORKAROUND: Add barrier=0 to root drive mount options 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).
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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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