CPU throttled to 12% with kernel 2.6.27

[Felix Kuehling]

Binary package hint: linux-image-2.6.27-1-generic

Description: Ubuntu intrepid (development branch)
Release: 8.10

After upgrading from linux-image-2.6.26-5-generic to linux-image-2.6.27-1-generic, the CPUs are running in throttling state T7 (12%). I have both kernels installed and I'm consistently getting T7 on 2.6.27 and T0 on 2.6.26. Needless to say that the system becomes unusably slow as a result with 2.6.27.

Hardware: HP Compaq 6715b notebook with AMD Turion(tm) 64 X2 Mobile Technology TL-56.
cat /proc/acpi/processor/C000/throttling (running the 2.6.26 kernel now)
state count: 8
active state: T0
state available: T0 to T7
states:
   *T0: 100%
    T1: 87%
    T2: 75%
    T3: 62%
    T4: 50%
    T5: 37%
    T6: 25%
    T7: 12%

With 2.6.26 I can change the throttling state. With 2.6.27 it shows T7 as the active state and I can't change it.

Furthermore I notice that the fan runs much faster on 2.6.27. At the same time the temperature is lower according to /proc/acpi/thermal_zone/TZ1/temperature and also felt at the exhaust vents. It's 50C with 2.6.26 (slow fan) and 43C with 2.6.27 (fast fan).

I don't see any messages in the kernel log about overheating. But the fan speed and throttling look to me like the system is thinking it's overheating and is throttling itself.

[kulight (kulight)]

any way to ad the info from my dupe that it would show it here ?

[kulight (kulight)]

i tried changing the cpu scaling through cpu freq applet which stuck on 800MHz but nothing happens
it stays on 800MHz no matter what i do (my cpu is 1.8 x2)

[tam (aznoohwee85)]

I can also confirm the cpu scaling bug for 2.6.27. I also recompiled the kernel from downstream and the problem has not been fixed.

[Simon Green (simongreen)]

I am also having the problem (HP Compaq 6715b) as is another friend with exactly the same laptop. It was a problem in both Intrepid Alpha 6 and Intrepid Beta. It was not a problem in Ubuntu 8.04.1 (all based on the i386 desktop editions). This is a critical bug IMO as it prevents the laptop from being able to be used successfully with Intrepid.

[Stefan Friesel (stefan-friesel)]

attaching dmesg from 2.6.26-5 and 2.6.27-4

one noteable change in 2.6.27 is:
-ACPI: Core revision 20080321
-ACPI: Looking for DSDT in initramfs... error, file /DSDT.aml not found.
+using C1E aware idle routine
+ACPI: Core revision 20080609
+ACPI: Checking initramfs for custom DSDT
+..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
 ..MP-BIOS bug: 8254 timer not connected to IO-APIC
+...trying to set up timer (IRQ0) through the 8259A ...
+..... (found apic 0 pin 2) ...
+....... works.
 CPU0: AMD Turion(tm) 64 X2 Mobile Technology TL-58 stepping 02
-Disabling APIC timer
+Using local APIC timer interrupts.
+APIC timer calibration result 12468829
+Detected 12.468 MHz APIC timer.

As a side effect, dyn-ticks are working. I don't know if this could be related.

[kieran (daralantarial)]

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e84956f92a846246b09b34f2a728329c386d250f

[kulight (kulight)]

"http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e84956f92a846246b09b34f2a728329c386d250f"

when will it reach ubuntu
final version of the kernel is out and the change log suggest it have been fixed or worked around

[kulight (kulight)]

well i tried updating my bios no change after that

also found this:
http://bugzilla.kernel.org/show_bug.cgi?id=11715

but i didnt understand how to do this blacklisting thing

[Oibaf (oibaf)]

According to the upstream bug, there should be a general fix for this problem in 2.6.27.1.

[Oibaf (oibaf)]

There is a patch available in the upstream bug:
http://bugzilla.kernel.org/show_bug.cgi?id=11516#c52

[kulight (kulight)]

is this bug going to be fixed before final release ?

i think it should be fixed before allot of people going to upgrade and find their laptop unusable

[Felix Kuehling (fxkuehl)]

It's fixed for me with kernel 2.6.27-7 x86_64 on Compaq 6715b.

[ufologe (holger-kirchner)]

Not fixed for me on Compaq nx6125 with kernel 2.6.27-7

[kulight (kulight)]

not fixed for me on a HP Compaq 6715s

[Stefan Friesel (stefan-friesel)]

kulight +1

[ufologe (holger-kirchner)]

Now it works on a HP Compaq nx6126 with Kernel 2.6.27-7.13, thanks!

[Timo Saloranta (timo-saloranta)]

kulight +1, tried it with and without "nohz=off"

[Leann Ogasawara (leannogasawara)]

Hi All,

The upstream patch referenced earlier is in the Intrepid kernel:

ogasawara@yoji:~/ubuntu-intrepid$ git log -p e84956f92a846246b09b34f2a728329c386d250f

commit e84956f92a846246b09b34f2a728329c386d250f

Author: Rafael J. Wysocki <email address hidden>

Date: Mon Oct 6 11:59:29 2008 +0200

    x86 ACPI: Blacklist two HP machines with buggy BIOSes

Felix Kuehling, the original bug reporter, has confirmed this is resolved - https://bugs.edge.launchpad.net/ubuntu/+source/linux/+bug/262066/comments/13 . For anyone still experiencing issues, it's probably best if you open a new bug report as this is a hardware specific issue so you will likely require a different fix. Feel free to add a reference to this bug report from your new one. Thanks.

[kulight (kulight)]

its the same bug
there is no reason to open a new one all that is needed to do is black list all the models that affected
nx6115 and 6715b that were blacklisted already and 6715s that for some reason left out

[Oibaf (oibaf)]

Use bug #280202 for the 6715s then.