Ubuntu
linux package

Consider disabling NEW_FAIR_SLEEPERS

Bug #436342 reported by Johan Kiviniemi
34
This bug affects 4 people
Affects Status Importance Assigned to Milestone
linux (Ubuntu)
Fix Released
Medium
Tim Gardner
Karmic
Fix Released
Medium
Tim Gardner

Bug Description

Due to latency problems with desktop interactivity when the NEW_FAIR_SLEEPERS scheduler feature is active, it was disabled by default for Linux 2.6.32, pending the bug being found and fixed.

http://git.kernel.org/?p=linux/kernel/git/x86/linux-2.6-tip.git;a=commitdiff;h=3f2aa307c4d26b4ed6509d0a79e8254c9e07e921

Please consider disabling it in Ubuntu kernels as well.

ProblemType: Bug
Architecture: i386
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ion 16762 F.... pulseaudio
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
Card0.Amixer.info:
 Card hw:0 'SB'/'HDA ATI SB at 0xd2400000 irq 16'
   Mixer name : 'Realtek ALC268'
   Components : 'HDA:10ec0268,103c30f1,00100003 HDA:10573055,103c30f1,00100700'
   Controls : 15
   Simple ctrls : 12
Date: Fri Sep 25 05:39:59 2009
DistroRelease: Ubuntu 9.10
MachineType: Hewlett-Packard HP Pavilion tx2500 Notebook PC
NonfreeKernelModules: fglrx
Package: linux-image-2.6.31-10-generic-pae 2.6.31-10.35
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.31-10-generic-pae root=UUID=cb73d396-bca3-4c05-95a2-212a4cecc0b2 ro quiet splash
ProcVersionSignature: Ubuntu 2.6.31-10.35-generic-pae
RelatedPackageVersions:
 linux-backports-modules-2.6.31-10-generic-pae 2.6.31-10.12
 linux-firmware 1.19
RfKill:

SourcePackage: linux
Uname: Linux 2.6.31-10-generic-pae i686
WpaSupplicantLog:

dmi.bios.date: 02/17/2009
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: F.0B
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 30F1
dmi.board.vendor: Quanta
dmi.board.version: 97.20
dmi.chassis.type: 10
dmi.chassis.vendor: Quanta
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnHewlett-Packard:bvrF.0B:bd02/17/2009:svnHewlett-Packard:pnHPPaviliontx2500NotebookPC:pvrRev1:rvnQuanta:rn30F1:rvr97.20:cvnQuanta:ct10:cvrN/A:
dmi.product.name: HP Pavilion tx2500 Notebook PC
dmi.product.version: Rev 1
dmi.sys.vendor: Hewlett-Packard

Revision history for this message
Johan Kiviniemi (ion) wrote :
Leann Ogasawara (leannogasawara)
Changed in linux (Ubuntu):
importance: Undecided → Medium
status: New → Triaged
Revision history for this message
Tim Gardner (timg-tpi) wrote :

http://kernel.ubuntu.com/git?p=ubuntu/ubuntu-karmic.git;a=commit;h=98399d89992af489d26f9b7191dc5502b7c63775

Changed in linux (Ubuntu):
assignee: nobody → Tim Gardner (timg-tpi)
status: Triaged → Fix Committed
Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package linux - 2.6.31-11.38

---------------
linux (2.6.31-11.38) karmic; urgency=low

  [ Stefan Bader ]

  * [Upstream] acerhdf: Limit modalias matching to supported boards
    - LP: #435958

  [ Tim Gardner ]

  * [Config] Added sata_via to d-i/modules/sata-modules
    - LP: #434827
  * SAUCE: (drop after 2.6.31) Disable iwl-1000 series wireless adapters
    - LP: #439285
  * [Upstream] i915: Fix i2c init message
    - LP: #409361
  * [Config] Add sym53c8xx.ko to virtual sub-flavour
    - LP: #439415

  [ Upstream Kernel Changes ]

  * sched: Disable NEW_FAIR_SLEEPERS for now
    - LP: #436342

  * ACPI video: ignore buggy _BQC
  * ACPI video: work-around BIOS AML bug in _BQC
    - LP: #428910
  * ALSA: hda - Added quirk to enable sound on Toshiba NB200
    - LP: #438318

 -- Tim Gardner <email address hidden> Thu, 01 Oct 2009 13:52:09 -0600

Changed in linux (Ubuntu Karmic):
status: Fix Committed → Fix Released
Revision history for this message
Markus Thielmann (thielmann) wrote :

Please notice that disabling NEW_FAIR_SLEEPERS made my system much slower. In fact, Karmic was the first release which allowed me to play tremulous in fullscreen with a nice speed. With NO_NEW_FAIR_SLEEPERS, the system is much slower.

Revision history for this message
Peter Cordes (peter-cordes) wrote :

Markus, and anyone else wondering about interactive performance regressions, NEW_FAIR_SLEEPERS is modifiable at run time; just run

echo NEW_FAIR_SLEEPERS | sudo tee /sys/kernel/debug/sched_features

grep --color=tty NEW_FAIR_SLEEPERS /sys/kernel/debug/sched_features

(Ubuntu mounts linux's debugfs at /sys/kernel/debug, not at /debug like you see referenced on the lkml threads talking about this.)

 To enable for every reboot, put
echo NEW_FAIR_SLEEPERS > /sys/kernel/debug/sched_features
 in /etc/rc.local, or whatever.

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