[Bug 10564] New: Randomly sets max freq equal to min freq

[Bug 10564] New: Randomly sets max freq equal to min freq

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=10564

           Summary: Randomly sets max freq equal to min freq
           Product: Power Management
           Version: 2.5
     KernelVersion: 2.6.24/25
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: cpufreq
        AssignedTo: cpufreq@www.linux.org.uk
        ReportedBy: stonecrest@gmail.com


Dell Latitude C400
i686 Mobile Intel(R) Pentium(R) III CPU - M 1200MHz GenuineIntel GNU/Linux


Usually within 5 minutes of booting up, after the computer has been off while
I'm at work or sleeping, cpufreq will suddenly revert to the lowest freq and
remain stuck in it. Before this happens, scaling works fine. I'm using the
ondemand governor. I can reboot (the only way to fix it) and then it will
typically work fine - up until I shut down for another longish period of time
and boot up again.


Here's cpufreq debug output where it changes:
cpufreq-core: updating policy for CPU 0
cpufreq-core: setting new policy for CPU 0: 800000 - 1200000 kHz
acpi-cpufreq: acpi_cpufreq_verify
acpi-cpufreq: acpi_cpufreq_verify
cpufreq-core: new min and max freqs are 800000 - 800000 kHz
cpufreq-core: governor: change or update limits
cpufreq-core: __cpufreq_governor for CPU 0, event 3
cpufreq-core: target for CPU 0: 800000 kHz, relation 1
acpi-cpufreq: acpi_cpufreq_target 800000 (0)
cpufreq-core: notification 0 of frequency transition to 800000 kHz
cpufreq-core: notification 1 of frequency transition to 800000 kHz


$ grep "" /sys/devices/system/cpu/cpu0/cpufreq/*
/sys/devices/system/cpu/cpu0/cpufreq/affected_cpus:0
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq:1200000
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq:800000
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies:1200000
800000 
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors:userspace
ondemand performance 
/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq:800000
/sys/devices/system/cpu/cpu0/cpufreq/scaling_driver:acpi-cpufreq
/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor:ondemand
/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq:800000
/sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq:800000
/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed:<unsupported>


Let me know if I should provide anything else, since it's easily reproducible.
It's been occurring for the last 2-3 months and is pretty much unusable in this
state, so I've been rebooting often.


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[Bug 10564] Randomly sets max freq equal to min freq

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http://bugzilla.kernel.org/show_bug.cgi?id=10564


akpm@osdl.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |akpm@osdl.org




------- Comment #1 from akpm@osdl.org  2008-04-27 09:35 -------
Is this a regression?  Did any earlier kernel work OK?  If so, which version?

Thanks.


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[Bug 10564] Randomly sets max freq equal to min freq

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http://bugzilla.kernel.org/show_bug.cgi?id=10564


andrew@andrewyates.net changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrew@andrewyates.net




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[Bug 10564] Randomly sets max freq equal to min freq

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http://bugzilla.kernel.org/show_bug.cgi?id=10564





------- Comment #2 from andrew@andrewyates.net  2008-04-27 10:14 -------
I have the same problem, but with this CPU: Intel(R) Core(TM)2 Duo CPU    
T9300  @ 2.50GHz

For me, the problem can sometimes be triggered by removing the battery while
the AC is plugged in. With both battery and AC, cpufreq works as normal, but
when I remove the battery I cannot set a frequency higher than 1.2GHz.

I did not notice this problem before 2.6.24.2, but I started using this laptop
soon before .24.2 was released so I cannot confirm whether or not it's a
regression.


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[Bug 10564] Randomly sets max freq equal to min freq

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http://bugzilla.kernel.org/show_bug.cgi?id=10564





------- Comment #3 from stonecrest@gmail.com  2008-04-27 10:30 -------
Andrew,

Yes it's a regression, cpufreq scaling has worked properly for years with this
laptop. I'm unsure which kernel version it started with (I'd guess it's around
2.6.24), but I'll do some testing with different versions and see if I can
narrow it down.


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[Bug 10564] Randomly sets max freq equal to min freq

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akpm@osdl.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Regression|0                           |1




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[Bug 10564] Randomly sets max freq equal to min freq

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------- Comment #4 from andrew@andrewyates.net  2008-04-27 11:35 -------
I should point out that the summary ("Randomly sets max freq equal to min
freq") is not entirely correct in my case.
My min freq is 800mhz and max is 2.5ghz. cpufreq refuses to set any speed
higher than 1.2ghz, which is one step up from my minimum. Any attempts to set
the CPU to a frequency higher than 1.2ghz fail, but I can change between 1.2ghz
and 800mhz.

$ grep "" /sys/devices/system/cpu/cpu0/cpufreq/*
/sys/devices/system/cpu/cpu0/cpufreq/affected_cpus:0 1
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq:800000
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq:2501000
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq:800000
/sys/devices/system/cpu/cpu0/cpufreq/phc_controls:77:41 76:34 10:30 8:27 6:23
136:19 
/sys/devices/system/cpu/cpu0/cpufreq/phc_default_controls:77:41 76:34 10:30
8:27 6:23 136:19 
/sys/devices/system/cpu/cpu0/cpufreq/phc_default_vids:41 34 30 27 23 19 
/sys/devices/system/cpu/cpu0/cpufreq/phc_fids:77 76 10 8 6 136 
/sys/devices/system/cpu/cpu0/cpufreq/phc_version:0.3.0
/sys/devices/system/cpu/cpu0/cpufreq/phc_vids:41 34 30 27 23 19 
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies:2501000
2500000 2000000 1600000 1200000 800000 
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors:ondemand
performance 
/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq:800000
/sys/devices/system/cpu/cpu0/cpufreq/scaling_driver:acpi-cpufreq
/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor:ondemand
/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq:1200000
/sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq:800000

$ cpufreq-info
cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006
Report errors and bugs to linux@brodo.de, please.
analyzing CPU 0:
  driver: acpi-cpufreq
  CPUs which need to switch frequency at the same time: 0 1
  hardware limits: 800 MHz - 2.50 GHz
  available frequency steps: 2.50 GHz, 2.50 GHz, 2.00 GHz, 1.60 GHz, 1.20 GHz,
800 MHz
  available cpufreq governors: ondemand, performance
  current policy: frequency should be within 800 MHz and 1.20 GHz.
                  The governor "ondemand" may decide which speed to use
                  within this range.
  current CPU frequency is 800 MHz (asserted by call to hardware).


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[Bug 10564] Randomly sets max freq equal to min freq

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http://bugzilla.kernel.org/show_bug.cgi?id=10564





------- Comment #5 from andrew@andrewyates.net  2008-04-27 11:38 -------
I forgot to mention that I get the same behavior with the userspace governor; I
had forgotten to load the module above.


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[Bug 10564] Randomly sets max freq equal to min freq

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trenn@suse.de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |davej@codemonkey.org.uk




------- Comment #6 from trenn@suse.de  2008-04-28 08:26 -------
Could this be a duplicate of:
http://bugzilla.kernel.org/show_bug.cgi?id=9708
Do you both use acpi-cpufreq?

If yes, the patch there should be added. Dave asked me to send him a reminder
(should have done so last weeek...), hope adding you here is enough...


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[Bug 10564] Randomly sets max freq equal to min freq

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------- Comment #7 from stonecrest@gmail.com  2008-04-28 11:54 -------
Yes, we both use acpi-cpufreq. For what it's worth, I always use my laptop
plugged into AC, so hopefully that other bug report is not specific to
switching power state. 

I'll be happy to test a kernel with this patch, thanks for pointing it out.


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[Bug 10564] Randomly sets max freq equal to min freq

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------- Comment #8 from trenn@suse.de  2008-04-30 03:29 -------
commit e56a727b023d40d1adf660168883f30f2e6abe0a
Author: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Date:   Mon Apr 28 15:13:43 2008 -0400

    [CPUFREQ] Make acpi-cpufreq more robust against BIOS freq changes behind
our back.

If this does not help, I wonder whether ignore_ppc=1 as processor module
parameter helps?


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------- Comment #9 from stonecrest@gmail.com  2008-05-03 07:41 -------
I just tried 2.6.25-git19, which has the above cpufreq commit, and still
observe the problem. 


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------- Comment #10 from stonecrest@gmail.com  2008-05-03 08:13 -------
I also now tried ignore_ppc=1. This is interesting, as cpufreq-info shows the
correct min/max frequencies, but I can tell that the issue is definitely not
resolved. Things were normal when I first booted up, but now I'm back to the
system not even being able to keep up with my typing and everything sluggish.
So despite cpufreq-info reporting the correct max freq, I don't know that
anything else fundamentally changed.

It looks like there are a number of people with this issue
(http://bbs.archlinux.org/viewtopic.php?pid=363228#p363228), and they claim it
started with the 2.6.24 kernel. That's consistent with what I guessed, although
I have not yet verified that this was definitely the kernel version where
things changed. And I should note that I'm testing on the mainline kernel
without patches, despite the reference to Archlinux.


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trenn@suse.de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |venkatesh.pallipadi@intel.co
                   |                            |m




------- Comment #11 from trenn@suse.de  2008-05-03 09:50 -------
> but now I'm back to the system not even being able to keep up with my typing
> and everything sluggish.
Puhh, could be the latest locking changes? Maybe irqs are held too long or
similar?

Scott, if you could do a git bisect, as you already know about which kernel
versions are affected it shouldn't be that much work...
If you could tell Venkatesh which patch it is then, it should be easy to fix.

You should spinlock debug compile in, maybe you already get a hint that
somewhere things get stuck for a while...


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