[Bug 10144] New: Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

[Bug 10144] New: Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=10144

           Summary: Wrong cpufreq speeds detected when overclocking (speeds
                    reported using stock FSB, not overclocked)
           Product: Power Management
           Version: 2.5
     KernelVersion: 2.6.22.17-0.1-default
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: cpufreq
        AssignedTo: cpufreq@www.linux.org.uk
        ReportedBy: knuckles@gmail.com


Latest working kernel version: Don't know
Earliest failing kernel version: Don't know
Distribution: openSUSE, Ubuntu
Hardware Environment: ASUS P5K (latest bios: 0902), Intel E2180, 2GB Ram
Software Environment: Normal opensuse install
Problem Description:

The E2180 is spec'd to work with 200Mhz front side bus, and has 6x thru 10x
multipliers, so, with speedstep, it should go from 1.2ghz to 2.0ghz, and that
happens fine.

The problem is, I overclocked the frontside bus to 313Mhz, (and still have
speedstep enabled), so speeds should be between 1.88ghz and 3.13ghz, but the
problem is cpufreq still reports the "available" speeds as being between 1.2
and 2.0ghz. I think this is only visual, since when booting the kernel says
"Detected 3130.093 MHz processor.", but after booting, /proc/cpuinfo and other
places all assume the aforementioned speeds.

I've also tested, and this still happens on Ubuntu Herdy alpha 5 that uses
2.6.24.2, so this should be distro-unrelated.

Steps to reproduce:
Overclock the FSB, and check reported cpufreq speeds.


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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http://bugzilla.kernel.org/show_bug.cgi?id=10144





------- Comment #1 from knuckles@gmail.com  2008-03-02 07:43 -------
Created an attachment (id=15105)
 --> (http://bugzilla.kernel.org/attachment.cgi?id=15105&action=view)
cat /proc/cpuinfo


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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http://bugzilla.kernel.org/show_bug.cgi?id=10144





------- Comment #2 from knuckles@gmail.com  2008-03-02 07:44 -------
Created an attachment (id=15106)
 --> (http://bugzilla.kernel.org/attachment.cgi?id=15106&action=view)
acpidump output


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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http://bugzilla.kernel.org/show_bug.cgi?id=10144





------- Comment #3 from knuckles@gmail.com  2008-03-02 07:46 -------
Created an attachment (id=15107)
 --> (http://bugzilla.kernel.org/attachment.cgi?id=15107&action=view)
dmesg

I'm using nvidia binary module, but this happens when I use other kernels and
the nv opensource driver, so it's not related.


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=10144





------- Comment #4 from knuckles@gmail.com  2008-03-02 07:49 -------
Created an attachment (id=15108)
 --> (http://bugzilla.kernel.org/attachment.cgi?id=15108&action=view)
cpufreq-info output


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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http://bugzilla.kernel.org/show_bug.cgi?id=10144


trenn@suse.de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |corentincj@iksaif.net




------- Comment #5 from trenn@suse.de  2008-03-02 11:52 -------
This ACPI device looks quite powerful, it seems to be a new ASUS specific ACPI
device we do not support yet:
Device (ASOC)
{
     Name (_HID, "ATK0110")
Maybe Corentin knows more about this machine, do you know about this device?
There also overclocking data and much more is included...

The cpufreq tables are included in another table that gets loaded at runtime.
Hopefully you can fetch them via:
acpidump --addr 0x7FF8E0D0 --length 0x0214 >ssdt_table_cpu0.dump
acpidump --addr 0x7FF8E2F0 --length 0x0143 >ssdt_table_cpu2.dump

Two should be enough..., can you attach these (best each and as plain text,
that's easier to handle).

Hmm before you attach new tables, you should make sure you run the latest BIOS.
If not and you still have problems, better re-attach acpidump.
CPUfreq problems often get resolved with a BIOS update on rather new machines.


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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http://bugzilla.kernel.org/show_bug.cgi?id=10144





------- Comment #6 from knuckles@gmail.com  2008-03-02 15:17 -------
I just confirmed, release "0902" is the latest version of the bios.

I don't know if this is related to the device you are referring, but I have an
option in the bios called "ACPI Version" that is enabled, and it's description
says "Add additional tables as per ACPI 2.0 specifications". I've tried
disabling it and the cpufreq result is the same as with it enabled.


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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http://bugzilla.kernel.org/show_bug.cgi?id=10144





------- Comment #7 from knuckles@gmail.com  2008-03-02 15:20 -------
Created an attachment (id=15112)
 --> (http://bugzilla.kernel.org/attachment.cgi?id=15112&action=view)
acpidump --addr 0x0D0 --length 0x0214x0143 >ssdte_cpu0.dump


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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http://bugzilla.kernel.org/show_bug.cgi?id=10144





------- Comment #8 from knuckles@gmail.com  2008-03-02 15:20 -------
Created an attachment (id=15113)
 --> (http://bugzilla.kernel.org/attachment.cgi?id=15113&action=view)
acpidump --addr 0x2F0 --length 0x0143x0143 >ssdte_cpu2.dump


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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http://bugzilla.kernel.org/show_bug.cgi?id=10144





------- Comment #9 from davej@codemonkey.org.uk  2008-03-02 22:30 -------
if you overclock, you pretty much give up all hope of having the BIOS do the
right thing.  See http://www.codemonkey.org.uk/projects/cpufreq/common.php


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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http://bugzilla.kernel.org/show_bug.cgi?id=10144





------- Comment #10 from knuckles@gmail.com  2008-03-03 03:37 -------
Forgive me if what i'm saying is stupid and obvious, but that site mentions
that "Other than measuring the speed every time a transition occurred (which
isn't feasible as it would incur a noticable performance overhead), it isn't
possible for cpufreq to know the current speed if it doesn't match what the
BIOS tables tell it that multiplier maps to."

My understanding is that speedstep works by lowering the cpu multiplier, while
keeping other things constant (not sure about proc voltage, but they don't
matter much to this problem), so I have displayed 1.2, 1.6 and 2.0 ghz
corresponding to the even multipliers 6x, 8x and 10x on my processor (not sure
why the odd ones aren't used).

Now if we were to get the real maximum speed (real_max_speed), that is
multiplier * frontsidebus, and divide it by the maximum speed on the bios
tables (bios_max_speed), we would get basically
(multipler/multiplier)*(overclockedFSB/ratedFSB). Now overclockedFSB/ratedFSB
is a constant because speedstep doesn't touch the fsb, in my case it is 313/200
= 1.565.

Wouldn't it be possible to obtain this constant once, and then use it to
correct the shown possible speeds? Eg, instead of 1.2, 1.6, 2.0 as reported by
the bios, we would have 1.2*constant, 1.6*constant, 2.0*constant ghz, that
should be the correct speed the processor is working at, when overclocked.

When not overclocked, constant = 1, so no problem there (probably it would be
1.0000001 or something like that, but there could be a test and only consider
the difference if it's greater than x %).

Again, sorry if none of this makes sense, maybe i'm reading it wrong :)


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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------- Comment #11 from corentincj@iksaif.net  2008-03-03 07:03 -------
Don't know this machine, can you join a cat /proc/acpi/dsdt please ?


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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------- Comment #12 from knuckles@gmail.com  2008-03-03 07:07 -------
Created an attachment (id=15120)
 --> (http://bugzilla.kernel.org/attachment.cgi?id=15120&action=view)
cat /proc/acpi/dsdt


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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------- Comment #13 from linux@brodo.de  2008-05-28 06:20 -------
Well, overclocking isn't supported by cpufreq, so getting "wrong" frequency
measurements isn't at all surprising. Is this a valid bug?


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[Bug 10144] Wrong cpufreq speeds detected when overclocking (speeds reported using stock FSB, not overclocked)

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------- Comment #14 from knuckles@gmail.com  2008-05-28 11:26 -------
But if it works almost perfectly, and the only problem is the speed displayed,
why simply say "we don't support it"?
Are there really that many changes for cpufreq when the processor is under- or
overclocked.

I for one, think that cpufreq is *more* important when overclocking: my cpu is
working at a lower frequency and cooler when idle, and only works at a higher
frequency when needed, instead of all the time.


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