Comment 0 for bug 475706

I've installed fresh 9.10 and I'm with the defaults. This is how I've noticed the following behaviour and I want to share it.

As I have two cores - I've setup two cpufreq scaling monitors applets. By default my idle system is working on 1.00Ghz on both CPUs (cores to be precise).

In one console I do:
while :; do echo -n "" ; done

htop shows that CPU1 goes 100% and CPU1 scaling monitor shows that CPU1 goes 1.8Ghz (max) right away.

So I open another console and do:
while :; do echo -n "" ; done

but CPU0 goes 100% but CPU0 scalling monitor show that CPU0 is only at 1.33Ghz and this is not changing through time.

Now comes the funny part.

I press the Ctrl+c in one of the consoles and now both CPUs go 1.00Ghz while CPU0 is working 100% and the other almost idle !

I've recreated this behaviour few times (100% reproduction rate).

This behaviour is not visible when both CPUs use i.e. conservative cpufreq. I have no idea behind the logic ondeman cpufreq gov. is being driven, but for me ubuntu always had a problems with it.

The other thing is this - when watching the following in HD:
http://www.youtube.com/watch?v=zlfKdbWwruY

I'm unable to get any CPU to work on 1.8Ghz and the movie is skipping frequently due to underperformed decoding / display.

So I've played around and changed cpu?/cpufreq/ondemand/up_threshold from default 95 to 30 . Now everything is perfectly fine. The original funny behaviour is gone.

I think that 95 is way to high for default. I want my CPU to work on high speed if required and slow down if there's nothing to do. (as per http://www.lesswatts.org/projects/applications-power-management/race-to-idle.php )

Maybe 5% margin is not enough to catch quickly that the there's a CPU shortage here and there. I'm not sure, but someone with more time and knowledge should take a look at this.

ProblemType: Bug
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: dpc 1723 F.... pulseaudio
 /dev/snd/pcmC0D0p: dpc 1723 F...m pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xf1200000 irq 22'
   Mixer name : 'Realtek ALC883'
   Components : 'HDA:10ec0883,15580721,00100002 HDA:10573055,10573055,00100700'
   Controls : 28
   Simple ctrls : 17
Date: Thu Nov 5 19:21:02 2009
DistroRelease: Ubuntu 9.10
HibernationDevice: RESUME=UUID=32932d31-e3e8-4410-825a-26f418ee7240
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
MachineType: ARISTO Slim 1250
Package: linux-image-2.6.31-14-generic 2.6.31-14.48
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.31-14-generic root=UUID=95827051-2f3b-467f-9f8a-d99370280630 ro quiet splash
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-14.48-generic
RelatedPackageVersions:
 linux-backports-modules-2.6.31-14-generic N/A
 linux-firmware 1.24
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
Uname: Linux 2.6.31-14-generic x86_64
dmi.bios.date: 01/10/2008
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: SROSA001.86C.0038.D.080110
dmi.board.name: Slim 1250
dmi.board.vendor: ARISTO
dmi.board.version: Not Applicable
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 1
dmi.chassis.vendor: ARISTO
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvrSROSA001.86C.0038.D.080110:bd01/10/2008:svnARISTO:pnSlim1250:pvrNotApplicable:rvnARISTO:rnSlim1250:rvrNotApplicable:cvnARISTO:ct1:cvrN/A:
dmi.product.name: Slim 1250
dmi.product.version: Not Applicable
dmi.sys.vendor: ARISTO