Public bug reported:
First noticed symptom ; lagging keyboard, pausing audio.
Viewing processes in top / system monitor revealed that a kworker
process was spiking the CPU every ~10s
perf-top on the affected process output below
Amateur opinion : Looks like nouveau module is constantly polling
hardware via I2C bus, most of the time being spent spinning the CPU
while waiting for the slow I2C bus to complete data transfers. This
causes symptoms in whatever other modules happen to have landed in the
same kworker process ; a reboot cleared up the keyboard lag.
This is an Optimus laptop (Intel i915 / nvidia Quadro 3000M) ; the
desktop is running on the i915 hardware.
`sudo rmmod nouveau` # CPU peakiness stops
`sudo modprobe nouveau` # problem recommences
I shall probably workaround by blacklisting the nouveau module for the
time being ; other suggestions in #ubuntu-kernel included sending the
sysfs sequences that power off the nvidia hardware in an Optimus combo.
PerfTop: 258 irqs/sec kernel:100.0% exact: 0.0% [1000Hz cycles],
(target_pid: 100)
-----------------------------------------------------------------------------------------------------------------------------------
97.16% [kernel] [k] ioread32
1.16% [kernel] [k] delay_tsc
0.98% [kernel] [k] native_read_tsc
0.25% [nouveau] [k] nv50_i2c_getscl
0.21% [kernel] [k] _cond_resched
0.12% [i2c_algo_bit] [k] sclhi
0.07% [kernel] [k] acpi_cpufreq_target
0.04% [kernel] [k] __ticket_spin_lock
0.01% [kernel] [k] update_wall_time
0.00% [kernel] [k] perf_rotate_context
0.00% [kernel] [k] cpufreq_stat_notifier_trans
0.00% [kernel] [k] __rcu_pending
0.00% [nouveau] [k] nouveau_bios_embedded_edid
0.00% [kernel] [k] __schedule
0.00% [kernel] [k] ns_to_timespec
0.00% [mei] [k] mei_timer
0.00% [kernel] [k] tg_load_down
0.00% [kernel] [k] find_busiest_group
0.00% [kernel] [k] __x2apic_send_IPI_mask
0.00% [kernel] [k] logarithmic_accumulation
0.00% [kernel] [k] process_one_work
0.00% [kernel] [k] pick_next_task_stop
0.00% [kernel] [k] idle_balance
0.00% [kernel] [k] iowrite32
ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image-3.2.0-24-generic 3.2.0-24.37
ProcVersionSignature: Ubuntu 3.2.0-24.37-generic 3.2.14
Uname: Linux 3.2.0-24-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu7
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/controlC1: adrian 1931 F.... pulseaudio
/dev/snd/controlC0: adrian 1931 F.... pulseaudio
Card0.Amixer.info:
Card hw:0 'PCH'/'HDA Intel PCH at 0xf2560000 irq 56'
Mixer name : 'IDT 92HD90BXX'
Components : 'HDA:111d76e7,102804a4,00100102'
Controls : 19
Simple ctrls : 10
Card1.Amixer.info:
Card hw:1 'NVidia'/'HDA NVidia at 0xf0080000 irq 17'
Mixer name : 'Nvidia GPU 12 HDMI/DP'
Components : 'HDA:10de0012,10de0101,00100100'
Controls : 25
Simple ctrls : 5
Date: Mon May 14 14:11:18 2012
HibernationDevice: RESUME=UUID=b7c131ed-ddd8-49ba-822b-c2ea5c5f8354
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
MachineType: Dell Inc. Precision M6600
ProcFB:
0 nouveaufb
1 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-24-generic
root=UUID=ed5f31aa-d115-48e5-9013-a1c2783b59b0 ro quiet splash vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-3.2.0-24-generic N/A
linux-backports-modules-3.2.0-24-generic N/A
linux-firmware 1.79
SourcePackage: linux
StagingDrivers: mei
UpgradeStatus: Upgraded to precise on 2012-04-16 (27 days ago)
dmi.bios.date: 10/18/2011
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A07
dmi.board.name: 04YY4M
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias:
dmi:bvnDellInc.:bvrA07:bd10/18/2011:svnDellInc.:pnPrecisionM6600:pvr01:rvnDellInc.:rn04YY4M:rvrA00:cvnDellInc.:ct9:cvr:
dmi.product.name: Precision M6600
dmi.product.version: 01
dmi.sys.vendor: Dell Inc.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: Confirmed
** Tags: amd64 apport-bug precise staging
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https://bugs.launchpad.net/bugs/999125
Title:
nouveau module constantly polls i2c, consumes CPU, on unused nvidia /
Optimus
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