kernel-packages team mailing list archive

[Joseph Salisbury <joseph.salisbury@xxxxxxxxxxxxx>]

** Tags removed: kernel-key

-- 
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1219548

Title:
  sched_autogroup_enabled breaks niceness

Status in “linux” package in Ubuntu:
  Triaged

Bug description:
  With the default Ubuntu 13.04 sysctl settings and boot parameters,
  positively niced tasks are very clearly given a larger share of CPU
  time than they ought to be. The update-apt-xapian-index process, for
  instance, runs at niceness +19; but it still slows my Celeron M520
  laptop to a crawl. Likewise for other positively niced tasks.

  If, on the other hand, I boot with the 'noautogroup' kernel parameter
  (which sets kernel.sched_autogroup_enabled to 0), responsiveness is
  much better when running CPU heavy tasks at positive niceness.

  In both cases, processes are reported by top and ps as running at the
  correct niceness; it appears that the nice level is ignored silently.

  Autogrouping is supposed to provide better responsiveness under some
  loads, but I believe that breaking nice settings is too high a price.
  I think it would be a good idea to turn off
  kernel.sched_autogroup_enabled, until this behavior is fixed upstream.

  By the way, an important note: modifying the sched_autogroup_enabled sysctl on a running system will usually cause a kernel panic. Autogrouping needs to be turned off using 'noautogroup' as a boot parameter; if you try it using sysctl.conf you will get a nice kernel panic on boot.
  --- 
  ApportVersion: 2.9.2-0ubuntu8.3
  Architecture: i386
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  proteus    1939 F.... pulseaudio
  CurrentDmesg:
   [   23.536912] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
   [   70.086188] nr_pdflush_threads exported in /proc is scheduled for removal
   [   70.086403] sysctl: The scan_unevictable_pages sysctl/node-interface has been disabled for lack of a legitimate use case.  If you have one, please send an email to linux-mm@xxxxxxxxx.
   [  186.829290] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
  DistroRelease: Ubuntu 13.04
  HibernationDevice: RESUME=UUID=ef3fd95f-4429-4c81-8aa1-30d57be5d48c
  InstallationDate: Installed on 2013-09-01 (0 days ago)
  InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release i386 (20130424)
  MachineType: Acer, inc. Aspire 3680
  MarkForUpload: True
  Package: linux (not installed)
  PccardctlIdent:
   Socket 0:
     no product info available
  PccardctlStatus:
   Socket 0:
     no card
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-29-generic root=UUID=779c7e91-1548-4942-b184-7b10797b86b8 ro quiet splash autogroup vt.handoff=7
  ProcVersionSignature: Ubuntu 3.8.0-29.42-generic 3.8.13.5
  RelatedPackageVersions:
   linux-restricted-modules-3.8.0-29-generic N/A
   linux-backports-modules-3.8.0-29-generic  N/A
   linux-firmware                            1.106
  Tags:  raring
  Uname: Linux 3.8.0-29-generic i686
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
  dmi.bios.date: 10/27/06
  dmi.bios.vendor: Acer
  dmi.bios.version: v1.3216
  dmi.board.name: Prespa1
  dmi.board.vendor: Acer, Inc.
  dmi.board.version: Not Applicable
  dmi.chassis.type: 1
  dmi.chassis.vendor: Acer, Inc.
  dmi.chassis.version: N/A
  dmi.modalias: dmi:bvnAcer:bvrv1.3216:bd10/27/06:svnAcer,inc.:pnAspire3680:pvrNotApplicable:rvnAcer,Inc.:rnPrespa1:rvrNotApplicable:cvnAcer,Inc.:ct1:cvrN/A:
  dmi.product.name: Aspire 3680
  dmi.product.version: Not Applicable
  dmi.sys.vendor: Acer, inc.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1219548/+subscriptions