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["Christopher M. Penalver" <christopher.m.penalver@xxxxxxxxx>]

** Changed in: linux (Ubuntu)
   Importance: Medium => Low

** Changed in: linux (Ubuntu)
       Status: Incomplete => Confirmed

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https://bugs.launchpad.net/bugs/1058864

Title:
  Poor mutex and semaphore performance

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  I noticed the results of this blog post:
  http://mr-edd.co.uk/blog/sad_state_of_osx_pthread_mutex_t
  and I was curious if the same sort of issue existed with the linux kernel and if it would shed any light on Bug #1058854
  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1058854

  The results don't appear to be as bad as those seen on Mac OS X, but they definitely are a lot poorer than I expected/hoped they would be. The code that builds on Linux is now available on that blog port and I created a git repo with the history here:
  https://github.com/daveisfera/test_mutex

  Here are the results from running it on the the same HP Pavilion dm4 that as the results from Bug #1058854:
  mutex
   1 thread  real 0m 0.514s user 0m 0.512s sys 0m 0.000s
   2 threads real 0m 4.382s user 0m 5.176s sys 0m 3.544s
   4 threads real 0m 9.953s user 0m 9.709s sys 0m22.417s
   8 threads real 0m20.984s user 0m14.973s sys 1m 8.256s
  16 threads real 0m38.725s user 0m28.426s sys 2m 5.484s

  benaphore
   1 thread  real 0m 0.324s user 0m 0.312s sys 0m 0.008s
   2 threads real 0m 6.372s user 0m 6.380s sys 0m 5.572s
   4 threads real 0m17.820s user 0m12.273s sys 0m42.495s
   8 threads real 0m40.266s user 0m25.626s sys 2m14.400s
  16 threads real 1m40.090s user 0m52.939s sys 5m45.802s

  mutex2
   1 thread  real 0m 0.325s user 0m 0.320s sys 0m 0.004s
   2 threads real 0m 0.730s user 0m 0.816s sys 0m 0.384s
   4 threads real 0m 2.328s user 0m 3.388s sys 0m 5.704s
   8 threads real 0m 4.096s user 0m 5.328s sys 0m10.705s
  16 threads real 0m 7.584s user 0m 9.609s sys 0m20.401s
  --- 
  AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
  ApportVersion: 2.0.1-0ubuntu13
  Architecture: amd64
  ArecordDevices:
   **** List of CAPTURE Hardware Devices ****
   card 0: PCH [HDA Intel PCH], device 0: STAC92xx Analog [STAC92xx Analog]
     Subdevices: 1/1
     Subdevice #0: subdevice #0
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  dlj        1876 F.... pulseaudio
  Card0.Amixer.info:
   Card hw:0 'PCH'/'HDA Intel PCH at 0xc0800000 irq 50'
     Mixer name	: 'Intel CougarPoint HDMI'
     Components	: 'HDA:111d76e0,103c1793,00100102 HDA:80862805,103c1793,00100000'
     Controls      : 22
     Simple ctrls  : 10
  DistroRelease: Ubuntu 12.04
  InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120823.1)
  MachineType: Hewlett-Packard HP Pavilion dm4 Notebook PC
  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-3.2.0-31-generic root=UUID=162256F02256D479 loop=/hostname/disks/root.disk ro quiet splash vt.handoff=7
  ProcVersionSignature: Ubuntu 3.2.0-31.50-generic 3.2.28
  RelatedPackageVersions:
   linux-restricted-modules-3.2.0-31-generic N/A
   linux-backports-modules-3.2.0-31-generic  N/A
   linux-firmware                            1.79.1
  StagingDrivers: rts_pstor mei
  Tags:  precise running-unity staging
  Uname: Linux 3.2.0-31-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
  dmi.bios.date: 01/17/2012
  dmi.bios.vendor: Hewlett-Packard
  dmi.bios.version: F.08
  dmi.board.asset.tag: Base Board Asset Tag
  dmi.board.name: 1793
  dmi.board.vendor: Hewlett-Packard
  dmi.board.version: 41.1C
  dmi.chassis.asset.tag: Chassis Asset Tag
  dmi.chassis.type: 10
  dmi.chassis.vendor: Hewlett-Packard
  dmi.chassis.version: Chassis Version
  dmi.modalias: dmi:bvnHewlett-Packard:bvrF.08:bd01/17/2012:svnHewlett-Packard:pnHPPaviliondm4NotebookPC:pvr068E100002204710000622100:rvnHewlett-Packard:rn1793:rvr41.1C:cvnHewlett-Packard:ct10:cvrChassisVersion:
  dmi.product.name: HP Pavilion dm4 Notebook PC
  dmi.product.version: 068E100002204710000622100
  dmi.sys.vendor: Hewlett-Packard

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