[Bug 10968] New: p4-clockmod reports false frequency

[Bug 10968] New: p4-clockmod reports false frequency

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=10968

           Summary: p4-clockmod reports false frequency
           Product: Power Management
           Version: 2.5
     KernelVersion: 2.6.25.7
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: cpufreq
        AssignedTo: cpufreq@www.linux.org.uk
        ReportedBy: ott@enolink.de


# uname -a
Linux hyperix 2.6.25.7 #2 Sat Jun 21 14:12:02 CEST 2008 i686 Intel(R)
Pentium(R) 4 CPU 1.80GHz GenuineIntel GNU/Linux
# cat /proc/cpuinfo 
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 1
model name      : Intel(R) Pentium(R) 4 CPU 1.80GHz
stepping        : 2
cpu MHz         : 3650.000
cache size      : 256 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pebs bts
bogomips        : 3603.33
clflush size    : 64

# cpufreq-info 
cpufrequtils 0.4: cpufreq-info (C) Dominik Brodowski 2004
Report errors and bugs to linux@brodo.de, please.
analyzing CPU 0:
  driver: p4-clockmod
  CPUs which need to switch frequency at the same time: 0
  hardware limits: 3.65 GHz - 14.60 GHz
  available frequency steps: 3.65 GHz, 5.48 GHz, 7.30 GHz, 9.13 GHz, 10.95 GHz,
12.78 GHz, 14.60 GHz
  available cpufreq governors: ondemand, userspace
  current policy: frequency should be within 3.65 GHz and 14.60 GHz.
                  The governor "ondemand" may decide which speed to use
                  within this range.
  current CPU frequency is 5.48 GHz (asserted by call to hardware).

Latest working kernel version: 2.6.23 (last version that I tried)

Any suggestions?

To me it seems that the bit shift width is incorrect. I had a similar problems
years ago and fixed by adding a different bit shift width for Pentium 4 Model 0
and 1.


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[Bug 10968] p4-clockmod reports false frequency

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=10968


bunk@kernel.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bunk@kernel.org
         Regression|0                           |1




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[Bug 10968] p4-clockmod reports false frequency

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=10968





------- Comment #1 from ott@enolink.de  2008-07-05 04:40 -------
The bug was introduced in commit ed9cbcd40004904dbe61ccc16d6106a7de38c998. As
proposed in bug #7186 the fix seems to be wrong, but worked for most people. 


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[Bug 10968] p4-clockmod reports false frequency

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=10968





------- Comment #2 from ott@enolink.de  2008-07-07 06:02 -------
According to the Intel specification there is no such multiplier field in the
msr, so the frequency has to be measured by the tsc on Pentium 4 Model 0 and 1.
Does anyone disagree?


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[Bug 10968] p4-clockmod reports false frequency

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=10968





------- Comment #3 from ott@enolink.de  2008-07-18 15:08 -------
Created an attachment (id=16881)
 --> (http://bugzilla.kernel.org/attachment.cgi?id=16881&action=view)
calculates frequency based on tsc value

The attached patch should fix the issue forever more, because it conforms now
entirely to the specification.


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[Bug 10968] p4-clockmod reports false frequency

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=10968





------- Comment #4 from linux@brodo.de  2008-07-23 11:46 -------
patch looks good. Matthias-Christian, can you submit it with proper
signed-off-by-line to davej, and davej can you pick it up with my
Acked-by-line, please? Thanks!


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[Bug 10968] p4-clockmod reports false frequency

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=10968


ott@enolink.de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |CODE_FIX




------- Comment #5 from ott@enolink.de  2008-07-23 13:51 -------
Patch submitted.


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