You have been subscribed to a public bug: 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) ** Affects: linux (Ubuntu) Importance: Low Status: Incomplete ** Tags: amd64 apport-bug ext4 sata trusty -- Internal Hard drive extremely slow unless using barrier=0 on ext4 https://bugs.launchpad.net/bugs/1538040 You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
