2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by bert huber » Mon, 31 Jul 2006 21:10:06


i everybody,

Since 2.6.18-rc1, up to and including -rc3, cpufreq has died on me. It
worked fine in 2.6.16.9.

The whole cpufreq hierarchy in /sys/ is missing, nothing is reported during
bootup mentioning 'cpufreq', and when I build with all the cpufreq stuff
configured as modules, I see this:

$ lsmod
Module Size Used by
capability 3464 0
commoncap 5120 1 capability
acpi_cpufreq 4748 0
speedstep_lib 3716 0
cpufreq_userspace 3092 0
cpufreq_stats 3588 0
freq_table 3588 2 acpi_cpufreq,cpufreq_stats
cpufreq_powersave 1664 0
cpufreq_ondemand 4716 0
cpufreq_conservative 5280 0
b2c2_flexcop_pci 6936 0
b2c2_flexcop 22412 1 b2c2_flexcop_pci
mt352 5636 1 b2c2_flexcop
mt312 6660 1 b2c2_flexcop
bcm3510 8196 1 b2c2_flexcop
stv0299 8840 1 b2c2_flexcop
stv0297 6272 1 b2c2_flexcop
nxt200x 11396 1 b2c2_flexcop
lgdt330x 7196 1 b2c2_flexcop
psmouse 31624 0

# modprobe p4_clockmod
FATAL: Error inserting p4_clockmod
(/lib/modules/2.6.18-rc3/kernel/arch/i386/kernel/cpu/cpufreq/p4-clockmod.ko):
Device or resource busy

dmesg is silent on why this is. I've grepped the files in the cpufreq
directory, but none of them contain EBUSY.

Under 2.6.16.9, this was logged at startup:
[17179582.044000] p4-clockmod: P4/Xeon(TM) CPU On-Demand Clock Modulation
available

cpuinfo:
$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 4
model name : Intel(R) Pentium(R) 4 CPU 3.00GHz
stepping : 1
cpu MHz : 3000.298
cache size : 1024 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 5
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 pbe nx
constant_tsc pni monitor ds_cpl cid xtpr
bogomips : 6004.95

From .config:

#
# CPU Frequency scaling
#
CONFIG_CPU_FREQ=y
CONFIG_CPU_FREQ_TABLE=m
# CONFIG_CPU_FREQ_DEBUG is not set
CONFIG_CPU_FREQ_STAT=m
# CONFIG_CPU_FREQ_STAT_DETAILS is not set
CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y
# CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE is not set
CONFIG_CPU_FREQ_GOV_PERFORMANCE=y
CONFIG_CPU_FREQ_GOV_POWERSAVE=m
CONFIG_CPU_FREQ_GOV_USERSPACE=m
CONFIG_CPU_FREQ_GOV_ONDEMAND=m
CONFIG_CPU_FREQ_GOV_CONSERVATIVE=m

#
# CPUFreq processor drivers
#
CONFIG_X86_ACPI_CPUFREQ=m
CONFIG_X86_POWERNOW_K6=m
CONFIG_X86_POWERNOW_K7=m
CONFIG_X86_POWERNOW_K7_ACPI=y
CONFIG_X86_POWERNOW_K8=m
CONFIG_X86_POWERNOW_K8_ACPI=y
CONFIG_X86_GX_SUSPMOD=m
CONFIG_X86_SPEEDSTEP_CENTRINO=m
CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI=y
CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE=y
CONFIG_X86_SPEEDSTEP_ICH=m
CONFIG_X86_SPEEDSTEP_SMI=m
CONFIG_X86_P4_CLOCKMOD=m
CONFIG_X86_CPUFREQ_NFORCE2=m
CONFIG_X86_LONGRUN=m

dmesg output is on http://ds9a.nl/tmp/dmesg , full .config on
http://ds9a.nl/config

Please let me know how I can help solve this problem. Zwane, you are welcome
to ssh to my system if that helps, let me know.

Kind regards,

bert



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2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by Tomasz Tor » Tue, 01 Aug 2006 01:10:10


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I have similar problem with cpufreq-nforce2 -- http://www.yqcomputer.com/
I haven't do a git-bisect yet.

--
Tomasz Torcz "God, root, what's the difference?"
XXXX@XXXXX.COM "God is more forgiving."


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2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by Zwane Mwai » Tue, 01 Aug 2006 02:50:07


Could you fellows try it without;

CONFIG_X86_SPEEDSTEP_CENTRINO
CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI
CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE
CONFIG_X86_SPEEDSTEP_ICH
CONFIG_X86_SPEEDSTEP_SMI
CONFIG_X86_ACPI_CPUFREQ

It may likely be a driver registration thing.

Thanks,
Zwane

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2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by Arjan van » Tue, 01 Aug 2006 04:50:08


as a side note ... you realize that clockmod doesn't actually save you
any power right? ;)


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2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by bert huber » Tue, 01 Aug 2006 05:00:09


Indeed, and I've measured that too. But it saves an awful amount of noise!

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2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by Tomasz Tor » Tue, 01 Aug 2006 15:40:04


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I had those =n


I had this one =y. After setting =n, cpufreq-nforce2 (=m) works again.

powernowd: PowerNow Daemon v0.96, (c) 2003-2005 John Clemens
powernowd: Found 1 cpu: -- 1 thread (or core) per physical cpu
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies: No
such file or directory
powernowd: cpu0: 1228Mhz - 1753Mhz (7 steps)

--
Tomasz Torcz "Never underestimate the bandwidth of a station
XXXX@XXXXX.COM wagon filled with backup tapes." -- Jim Gray


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2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by David Ree » Tue, 01 Aug 2006 17:00:08


If it doesn't save you power, how does it reduce noise? I guess it
keeps you from overheating your processor which causes the fan to spin
up?

-Dave
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2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by bert huber » Tue, 01 Aug 2006 17:20:07


I have no idea. Perhaps heat production moves somewhere else. But you are
free to come listen to the difference p4-clockmod makes for me.

Thanks.

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2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by Zwane Mwai » Tue, 01 Aug 2006 23:10:12


Hi Tomasz,

Could you also please test Bert's patch which propogates error
return values with your previous configuration?

Thanks,
Zwane
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2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by Tomasz Tor » Wed, 02 Aug 2006 00:30:08


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Bert's patch works. With CONFIG_X86_ACPI_CPUFREQ=y and
cpufre-nforce2=m I have working cpufreq (like in 2.6.17 and before).

--
Tomasz Torcz "Never underestimate the bandwidth of a station
XXXX@XXXXX.COM wagon filled with backup tapes." -- Jim Gray


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2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by Robert Han » Wed, 02 Aug 2006 04:20:13


The aim of power-saving techniques is to allow the same amount of
computational work to be done while consuming less power. For example,
if a task only uses 20% of the CPU at its maximum speed, the clock speed
can be dropped down to half of the maximum. The main advantage of this
is that it allows reducing the core voltage which I think accounts for
most of the power savings. Essentially the lower performance settings
have higher performance per watt than the higher settings.

Clock modulation doesn't reduce the CPU core voltage, nor does it reduce
the rate at which power is consumed when the CPU is in the active state.
It just causes the CPU to periodically stop its clock for a while,
during which no work is done. This means that the power and heat
produced is reduced but the work that can be done is also reduced by an
proportional amount, so there is little or no improvement in performance
per watt. As well, when the CPU has nothing to do it will be halted
anyway which does pretty much the same as what clockmod is doing.

Essentially clockmod is there as a way to limit the thermal output of
the CPU in thermal emergencies, it's not really very good as a
power-saving feature.

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2.6.18 regression: cpufreq broken since 2.6.18-rc1 on pentium4

Post by bert huber » Wed, 02 Aug 2006 04:40:09


You are empirically wrong in my case. I can't make you hear the difference
in noise, but perhaps this will convince you:

$ sensors | grep CPU
CPU_Fan: 2359 RPM (min = 4000 RPM)
CPU: +61 C (low = +10 C, high = +50 C)

$ sudo /etc/init.d/powernowd start
* Starting powernowd... [ ok ]

$ sensors | grep CPU
CPU_Fan: 1411 RPM (min = 4000 RPM)
CPU: +57 C (low = +10 C, high = +50 C)

$ sudo /etc/init.d/powernowd stop
* Stopping powernowd: [ ok ]

$ sensors | grep CPU
CPU_Fan: 2452 RPM (min = 4000 RPM)
CPU: +61 C (low = +10 C, high = +50 C)

And this with only seconds in between starting and stopping, on an idle
system.


That I've measured, and indeed, the same amount of power is drawn from the
mains. But the reduction in fan noise is worth it.

On this CPU, HLT may simply not be doing as good a job. Who knows.

processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 4
model name : Intel(R) Pentium(R) 4 CPU 3.00GHz
stepping : 1
cpu MHz : 3000.000
cache size : 1024 KB

It does reduce effective CPU to 300MHz though, which is a lot.

Kind regards,

bert

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