p4-clockmod doesn't seem to allow the highest possible speed
Hi,
I can't seem to get my processor to run at full speed when using the p4-clockmod driver:
root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# cat scaling_governor userspace root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# cat scaling_max_freq 2193205 root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# echo 2193205 > scaling_setspeed root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# cat scaling_setspeed 1925000
What am I missing?
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Wouter Verhelst Debian GNU/Linux -- http://www.debian.org Nederlandstalige Linux-documentatie -- http://nl.linux.org "Stop breathing down my neck." "My breathing is merely a simulation." "So is my neck, stop it anyway!" -- Voyager's EMH versus the Prometheus' EMH, stardate 51462.
Quoted 13 lines · Wouter Verhelst
Hi,
I can't seem to get my processor to run at full speed when using the p4-clockmod driver:
root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# cat scaling_governor userspace root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# cat scaling_max_freq 2193205 root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# echo 2193205 > scaling_setspeed root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# cat scaling_setspeed 1925000
Quoted 1 line
What am I missing?
Which kernel version are you using? What does "dmesg" tell us?
Dominik
Quoted 14 lines · Dominik Brodowski
Quoted 13 lines · Wouter Verhelst
Hi,
I can't seem to get my processor to run at full speed when using the p4-clockmod driver:
root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# cat scaling_governor userspace root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# cat scaling_max_freq 2193205 root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# echo 2193205 > scaling_setspeed root@worldmusic:/sys/devices/system/cpu/cpu0/cpufreq# cat scaling_setspeed 1925000
Quoted 3 lines
Quoted 1 line
What am I missing?
Which kernel version are you using?
Vanilla 2.6.1, but I had the same problem with 2.6.0 (didn't try p4-clockmod on any kernel before that).
Quoted 1 line
What does "dmesg" tell us?
234 lines of output. Seems a bit excessive to put that in this mail, so I've put it on <http://users.pandora.be/wouter.verhelst/cpufreq.tgz>,
together with the contents of /proc/cpuinfo and my .config. If you need any further information, please ask.
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Wouter Verhelst Debian GNU/Linux -- http://www.debian.org Nederlandstalige Linux-documentatie -- http://nl.linux.org "Stop breathing down my neck." "My breathing is merely a simulation." "So is my neck, stop it anyway!" -- Voyager's EMH versus the Prometheus' EMH, stardate 51462.
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Quoted 2 lines · Wouter Verhelst
Vanilla 2.6.1, but I had the same problem with 2.6.0 (didn't try p4-clockmod on any kernel before that).
You shouldn't need to use p4-clockmod at all... speedstep-ich is a better choice for your system... Nonetheless, let us find the bug:
Quoted 6 lines
Quoted 1 line
What does "dmesg" tell us?
234 lines of output. Seems a bit excessive to put that in this mail, so I've put it on <http://users.pandora.be/wouter.verhelst/cpufreq.tgz>,
together with the contents of/proc/cpuinfoand my .config. If you need any further information, please ask.
Thank you very much. Two questions: Do the init scripts modprobe either the acpi module (acpi.ko) or the speedstep-ich module (speedstep-ich.ko) anyway? What does /proc/cpuinfo say before modprobing p4-clockmod, and after modprobing p4-clockmod?
Also, could you please uncomment the printk in line 190 of linux/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c and send me a diff of the dmesgs?
Thank you very much,
Dominik
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Op za 10-01-2004, om 14:18 schreef Dominik Brodowski:
Quoted 6 lines · Wouter Verhelst
Quoted 2 lines
Vanilla 2.6.1, but I had the same problem with 2.6.0 (didn't try p4-clockmod on any kernel before that).
You shouldn't need to use p4-clockmod at all... speedstep-ich is a better choice for your system...
Ah? Didn't know. OK, thanks :-)
(when checking the description now, it clearly says "P4-M"; must've missed that before)
Quoted 4 lines
Nonetheless, let us find the bug:
Quoted 2 lines
Quoted 1 line
What does "dmesg" tell us?
Quoted 8 lines
Quoted 4 lines
234 lines of output. Seems a bit excessive to put that in this mail, so I've put it on <http://users.pandora.be/wouter.verhelst/cpufreq.tgz>,
together with the contents of/proc/cpuinfoand my .config. If you need any further information, please ask.Thank you very much. Two questions: Do the init scripts modprobe either the acpi module (acpi.ko) or the speedstep-ich module (speedstep-ich.ko) anyway?
No. I compiled the ACPI module because I didn't want to convert my scripts right away and the speedstep-ich one because I wasn't sure which one to choose, but my /etc/modules (which lists modules to be loaded at boot time) contained p4-clockmod alone (contained, because it's speedstep-ich now ;-)
Quoted 2 lines
What does
/proc/cpuinfosay before modprobing p4-clockmod, and after modprobing p4-clockmod?
The only difference with the one you already have is the Mhz number (which seems logical). Before it's loaded, it's at 2194.424; Immediately after loading p4-clockmod, that number was still the same, but in the mean time it went back to 1919.054
Note that I had to reboot my box to unload the module. This is probably related to the above, but just in case it isn't: I cannot rmmod the p4-clockmod module, trying anyway results in rmmod segfaulting -- at least once the frequency has been altered. I didn't reboot again just to test that, but if you want, it's no problem.
Quoted 3 lines
Also, could you please uncomment the printk in line 190 of
linux/arch/i386/kernel/cpu/cpufreq/p4-clockmod.cand send me a diff of the dmesgs?
The extra line reads:
cpufreq: P4 - MSR_EBC_FREQUENCY_ID: 0x16300a16 0x0
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Quoted 5 lines
Note that I had to reboot my box to unload the module. This is probably related to the above, but just in case it isn't: I cannot rmmod the p4-clockmod module, trying anyway results in rmmod segfaulting -- at least once the frequency has been altered. I didn't reboot again just to test that, but if you want, it's no problem.
That's unrelated, and I was able to reproduce it on my notebook as well. The attached patch [which should apply with some offset] should fix that. (Davej:
it applies on top of the p4-clockmod-fixup. Please queue for merging with Linus, thanks.)
Quoted 7 lines · Wouter Verhelst
Quoted 2 lines
What does
/proc/cpuinfosay before modprobing p4-clockmod, and after modprobing p4-clockmod?The only difference with the one you already have is the Mhz number (which seems logical). Before it's loaded, it's at 2194.424; Immediately after loading p4-clockmod, that number was still the same, but in the mean time it went back to 1919.054
I think ACPI is messing with us. It detects a high temperature situation, tries to scale down the CPU, and forces down the CPU speed. Could you send me the output of /proc/acpi/processor/*/* and /proc/acpi/thermal_zone/*/* when you notice this situation again?
BTW, could it be that this is still the 2.6.0 module, instead of the 2.6.1 variant? 2.6.1 should report more "clean" values in /sys/devices/system/cpu/cpufreq/... it should report 2200000 instead of 2193205.
Dominik
Fix an OOPS in unloading. Reverting frequency changes on unloading is uncommon for cpufreq drivers, so let's remove this speciality.
arch/i386/kernel/cpu/cpufreq/p4-clockmod.c | 2 +- 1 files changed, 1 insertion(+), 1 deletion(-)
arch/i386/kernel/cpu/cpufreq/p4-clockmod.c +1 -1
@@ -246,7 +246,7 @@static int cpufreq_p4_cpu_exit (struct cpufreq_policy *policy) {cpufreq_frequency_table_put_attr (policy->cpu); -return cpufreq_p4_setdc (policy->cpu,DC_DISABLE ); +return 0 ; }static struct freq_attr * p4clockmod_attr[] = {
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Quoted 8 lines · Dominik Brodowski
Quoted 5 lines
Note that I had to reboot my box to unload the module. This is probably related to the above, but just in case it isn't: I cannot rmmod the p4-clockmod module, trying anyway results in rmmod segfaulting -- at least once the frequency has been altered. I didn't reboot again just to test that, but if you want, it's no problem.
That's unrelated, and I was able to reproduce it on my notebook as well. The attached patch [which should apply with some offset] should fix that.
OK, thanks.
[...]
Quoted 11 lines · Wouter Verhelst
Quoted 7 lines
Quoted 2 lines
What does
/proc/cpuinfosay before modprobing p4-clockmod, and after modprobing p4-clockmod?The only difference with the one you already have is the Mhz number (which seems logical). Before it's loaded, it's at 2194.424; Immediately after loading p4-clockmod, that number was still the same, but in the mean time it went back to 1919.054
I think ACPI is messing with us. It detects a high temperature situation, tries to scale down the CPU, and forces down the CPU speed.
Hm. This one got me thinking; I think I just found it. I forgot that I installed cpufreqd a while ago, which seems to be the culprit: when I start cpufreqd, the system falls back to 1925Mhz. I've removed it now, however, as killing cpufreqd does not release the maximum speed back to it's normal value of 2.2Ghz, I'm not entirely sure; so...
Quoted 2 lines
Could you send me the output of
/proc/acpi/processor/*/*and/proc/acpi/thermal_zone/*/*when you notice this situation again?
... I've still put those at
http://users.pandora.be/wouter.verhelst/proc-acpi.tgz
Quoted 4 lines
BTW, could it be that this is still the 2.6.0 module, instead of the 2.6.1 variant? 2.6.1 should report more "clean" values in
/sys/devices/system/cpu/cpufreq/... it should report 2200000 instead of 2193205.
Yes, the first mail I sent (with the command line stuff in /sys) was before I installed 2.6.1, still running 2.6.0 at that point. Sorry for the confusion :-)
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Wouter Verhelst Debian GNU/Linux -- http://www.debian.org Nederlandstalige Linux-documentatie -- http://nl.linux.org "Stop breathing down my neck." "My breathing is merely a simulation." "So is my neck, stop it anyway!" -- Voyager's EMH versus the Prometheus' EMH, stardate 51462.
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Quoted 1 line · Wouter Verhelst
That happens both when it's in P0 or P1.
So ACPI works to set the processor in P0 and P1? If so, you really really should use the ACPI cpufreq driver instead of the p4-clockmod driver. The former will offer you true "SpeedStep" support, the latter only some clock modulation which won't save you much energy as ACPI supports the C2 idle state anyway.
Quoted 1 line
Not that it matters -- p4-clockmod seems to do it right :)
It's not as noisy, indeed. But it's not right -- as long as acpi.ko works.
Quoted 9 lines
Quoted 2 lines
I think ACPI is messing with us. It detects a high temperature situation, tries to scale down the CPU, and forces down the CPU speed.
Hm. This one got me thinking; I think I just found it. I forgot that I installed cpufreqd a while ago, which seems to be the culprit: when I start cpufreqd, the system falls back to 1925Mhz. I've removed it now, however, as killing cpufreqd does not release the maximum speed back to it's normal value of 2.2Ghz, I'm not entirely sure; so...
Quoted 5 lines
Quoted 2 lines
Could you send me the output of
/proc/acpi/processor/*/*and/proc/acpi/thermal_zone/*/*when you notice this situation again?... I've still put those at
http://users.pandora.be/wouter.verhelst/proc-acpi.tgz
Hm, can't recognize anything strange there. When the situation appears again, what does /sys/devices/sytem/cpu/cpu0/cpufreq/scaling_max_freq say?
Quoted 8 lines
Quoted 4 lines
BTW, could it be that this is still the 2.6.0 module, instead of the 2.6.1 variant? 2.6.1 should report more "clean" values in
/sys/devices/system/cpu/cpufreq/... it should report 2200000 instead of 2193205.Yes, the first mail I sent (with the command line stuff in /sys) was before I installed 2.6.1, still running 2.6.0 at that point. Sorry for the confusion :-)
No problem :-)
Dominik
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Quoted 4 lines · Dominik Brodowski
Quoted 1 line · Wouter Verhelst
That happens both when it's in P0 or P1.
So ACPI works to set the processor in P0 and P1?
Yes.
Quoted 4 lines
If so, you really really should use the ACPI cpufreq driver instead of the p4-clockmod driver. The former will offer you true "SpeedStep" support, the latter only some clock modulation which won't save you much energy as ACPI supports the C2 idle state anyway.
Ah, so what p4-clockmod does is not SpeedStep?
Hm. That sucks.
Quoted 3 lines
Quoted 1 line
Not that it matters -- p4-clockmod seems to do it right :)
It's not as noisy, indeed. But it's not right -- as long as acpi.ko works.
It mostly does, although I've had lockups when using the /proc interface to switch CPU frequencies -- yes, should've reported that, but I only now remember :)
Quoted 9 lines
Quoted 9 lines
Quoted 2 lines
I think ACPI is messing with us. It detects a high temperature situation, tries to scale down the CPU, and forces down the CPU speed.
Hm. This one got me thinking; I think I just found it. I forgot that I installed cpufreqd a while ago, which seems to be the culprit: when I start cpufreqd, the system falls back to 1925Mhz. I've removed it now, however, as killing cpufreqd does not release the maximum speed back to it's normal value of 2.2Ghz, I'm not entirely sure; so...
Quoted 8 lines
Quoted 5 lines
Quoted 2 lines
Could you send me the output of
/proc/acpi/processor/*/*and/proc/acpi/thermal_zone/*/*when you notice this situation again?... I've still put those at
http://users.pandora.be/wouter.verhelst/proc-acpi.tgzHm, can't recognize anything strange there. When the situation appears again, what does
/sys/devices/sytem/cpu/cpu0/cpufreq/scaling_max_freqsay?
That does not change.
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Wouter Verhelst Debian GNU/Linux -- http://www.debian.org Nederlandstalige Linux-documentatie -- http://nl.linux.org "Stop breathing down my neck." "My breathing is merely a simulation." "So is my neck, stop it anyway!" -- Voyager's EMH versus the Prometheus' EMH, stardate 51462.
Quoted 7 lines · Wouter Verhelst
Quoted 4 lines · Dominik Brodowski
Quoted 1 line · Wouter Verhelst
That happens both when it's in P0 or P1.
So ACPI works to set the processor in P0 and P1?
Yes.
Excellent.
Quoted 9 lines
Quoted 5 lines
If so, you really really should use the ACPI cpufreq driver instead of the p4-clockmod driver. The former will offer you true "SpeedStep" support, the latter only some clock modulation which won't save you much energy as ACPI supports the C2 idle state anyway.
Ah, so what p4-clockmod does is not SpeedStep?
Hm. That sucks.
No. p4-clockmod stops the CPU for certain short periods of time, it "modulates" the CPU frequency.
------------------> time axis
x x x x x x x x x normal clock ticks x x x x - - - - x 50 % frequency modulation [ACPI T-States or P4-clockmod] x x x x x x frequency scaling [ACPI P-States]
Only if the frequency is scaled, the voltage can be scaled also. So only that offers the best reduction of energy usage. For details, check the cpufreq archives for a lengthy thread with many calculations...
Quoted 7 lines
Quoted 3 lines
Quoted 1 line
Not that it matters -- p4-clockmod seems to do it right :)
It's not as noisy, indeed. But it's not right -- as long as acpi.ko works.
It mostly does, although I've had lockups when using the /proc interface to switch CPU frequencies -- yes, should've reported that, but I only now remember :)
The /proc/ interface is deprecated, and the acpi module is full of errors [I'm working on it, though...]. You should use the /sys-fs interface with the acpi.ko module as well.
Quoted 1 line
That does not change.
Very strange... I'm out of ideas for the moment being.
Dominik
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Quoted 6 lines · Dominik Brodowski
Quoted 3 lines · Wouter Verhelst
It mostly does, although I've had lockups when using the /proc interface to switch CPU frequencies -- yes, should've reported that, but I only now remember :)
The
/proc/interface is deprecated,
Yes, I know. In fact, it being deprecated is the reason I started playing with p4-clockmod in the first place :)
Quoted 6 lines
and the acpi module is full of errors [I'm working on it, though...]. You should use the /sys-fs interface with the acpi.ko module as well.
Quoted 1 line
That does not change.
Very strange... I'm out of ideas for the moment being.
I'm more and more convinced it's got something to do with cpufreqd. I shut it down yesterday for about an hour, and nothing happened. Then I restarted it, and -surprise- less than a minute later, the CPU was throttled below the maximum speed.
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Wouter Verhelst Debian GNU/Linux -- http://www.debian.org Nederlandstalige Linux-documentatie -- http://nl.linux.org "Stop breathing down my neck." "My breathing is merely a simulation." "So is my neck, stop it anyway!" -- Voyager's EMH versus the Prometheus' EMH, stardate 51462.
Quoted 8 lines · Wouter Verhelst
Quoted 4 lines · Dominik Brodowski
Quoted 1 line · Wouter Verhelst
That happens both when it's in P0 or P1.
So ACPI works to set the processor in P0 and P1?
Yes.
Quoted 8 lines
Quoted 4 lines
If so, you really really should use the ACPI cpufreq driver instead of the p4-clockmod driver. The former will offer you true "SpeedStep" support, the latter only some clock modulation which won't save you much energy as ACPI supports the C2 idle state anyway.
Ah, so what p4-clockmod does is not SpeedStep?
Hm. That sucks.
No. p4-clockmod is not SpeedStep. Normal. As Dominik say, p4-clockmod is *not* intended for power comsuption issues.
There is normally two reasons for slowing a CPU:
1- change voltage of processor (SpeedStep, Powernow, etc.)
The usage for is to get more battery life, or to get less power comsuption for the system.
2- throttling the CPU via clock modulation (P4 only), or by generating
a signal which toggle the STP# pin of a CPU. The usage for it is to cool the CPU instead of turning on/off the CPU fan. It is also used if the fan is not sufficiant to cool enough the CPU.
1 and 2 do not have the same goal. The CPUFreq project currently only handle case 1- (via policy, governor, etc.). But I'm thinking about designing case 2- for the cpufreq core (there is already something for, but it is not exactly what I would expect), and that should rely on lm-sensors or/and ACPI thermal.
Cheers,
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Quoted 6 lines · Dominik Brodowski
Quoted 2 lines · Wouter Verhelst
Vanilla 2.6.1, but I had the same problem with 2.6.0 (didn't try p4-clockmod on any kernel before that).
You shouldn't need to use p4-clockmod at all... speedstep-ich is a better choice for your system...
This doesn't seem to work, it says 'No such device'. I have a VIA 82C686 south bridge, not an Intel one, so I guess that's the reason.
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Wouter Verhelst Debian GNU/Linux -- http://www.debian.org Nederlandstalige Linux-documentatie -- http://nl.linux.org "Stop breathing down my neck." "My breathing is merely a simulation." "So is my neck, stop it anyway!" -- Voyager's EMH versus the Prometheus' EMH, stardate 51462.
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Quoted 10 lines · Wouter Verhelst
Quoted 6 lines · Dominik Brodowski
Quoted 2 lines · Wouter Verhelst
Vanilla 2.6.1, but I had the same problem with 2.6.0 (didn't try p4-clockmod on any kernel before that).
You shouldn't need to use p4-clockmod at all... speedstep-ich is a better choice for your system...
This doesn't seem to work, it says 'No such device'. I have a VIA 82C686 south bridge, not an Intel one, so I guess that's the reason.
Unfortunately, you're right. VIA doesn't publish their spec sheets as Intel does, so there's no speedstep-via driver (yet). Maybe acpi.ko works?
Dominik
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Quoted 6 lines · Dominik Brodowski
Quoted 5 lines · Wouter Verhelst
Quoted 4 lines · Dominik Brodowski
Quoted 2 lines · Wouter Verhelst
Vanilla 2.6.1, but I had the same problem with 2.6.0 (didn't try p4-clockmod on any kernel before that).
Quoted 8 lines
Quoted 5 lines
Quoted 2 lines
You shouldn't need to use p4-clockmod at all... speedstep-ich is a better choice for your system...
This doesn't seem to work, it says 'No such device'. I have a VIA 82C686 south bridge, not an Intel one, so I guess that's the reason.
Unfortunately, you're right. VIA doesn't publish their spec sheets as Intel does, so there's no speedstep-via driver (yet). Maybe acpi.ko works?
It does, but when my CPU is throttled, it makes an uncomfortable sound at high frequency, so I try to avoid that.
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Wouter Verhelst Debian GNU/Linux -- http://www.debian.org Nederlandstalige Linux-documentatie -- http://nl.linux.org "Stop breathing down my neck." "My breathing is merely a simulation." "So is my neck, stop it anyway!" -- Voyager's EMH versus the Prometheus' EMH, stardate 51462.
Quoted 10 lines · Wouter Verhelst
Quoted 9 lines · Dominik Brodowski
Quoted 8 lines · Wouter Verhelst
Quoted 6 lines · Dominik Brodowski
Quoted 2 lines · Wouter Verhelst
Vanilla 2.6.1, but I had the same problem with 2.6.0 (didn't try p4-clockmod on any kernel before that).
You shouldn't need to use p4-clockmod at all... speedstep-ich is a better choice for your system...
Quoted 9 lines
Quoted 5 lines
Quoted 2 lines
This doesn't seem to work, it says 'No such device'. I have a VIA 82C686 south bridge, not an Intel one, so I guess that's the reason.
Unfortunately, you're right. VIA doesn't publish their spec sheets as Intel does, so there's no speedstep-via driver (yet). Maybe acpi.ko works?
It does, but when my CPU is throttled, it makes an uncomfortable sound at high frequency, so I try to avoid that.
Do you mean the processor is at high speed (performance), and throttling is enabled?
So it should not be even surprising.
The P4 is able to throttle itself, so I guess the throttling things done externally by the south bridge would have not even been tested by the platform designer...
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Ducrot Bruno -- Which is worse: ignorance or apathy? -- Don't know. Don't care.
Quoted 9 lines · Ducrot Bruno
Quoted 7 lines · Wouter Verhelst
Quoted 3 lines · Dominik Brodowski
Unfortunately, you're right. VIA doesn't publish their spec sheets as Intel does, so there's no speedstep-via driver (yet). Maybe acpi.ko works?
It does, but when my CPU is throttled, it makes an uncomfortable sound at high frequency, so I try to avoid that.
Quoted 8 lines
Do you mean the processor is at high speed (performance), and throttling is enabled?
So it should not be even surprising.
The P4 is able to throttle itself, so I guess the throttling things done externally by the south bridge would have not even been tested by the platform designer...
Uh, I'm not entirely sure I understand what you mean here. The issue is:
when I put the processor in some other T-state than T0, it makes noise. That happens both when it's in P0 or P1.
Not that it matters -- p4-clockmod seems to do it right :)
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Wouter Verhelst Debian GNU/Linux -- http://www.debian.org Nederlandstalige Linux-documentatie -- http://nl.linux.org "Stop breathing down my neck." "My breathing is merely a simulation." "So is my neck, stop it anyway!" -- Voyager's EMH versus the Prometheus' EMH, stardate 51462.
Quoted 15 lines · Wouter Verhelst
Quoted 14 lines · Ducrot Bruno
Quoted 7 lines · Wouter Verhelst
Quoted 3 lines · Dominik Brodowski
Unfortunately, you're right. VIA doesn't publish their spec sheets as Intel does, so there's no speedstep-via driver (yet). Maybe acpi.ko works?
It does, but when my CPU is throttled, it makes an uncomfortable sound at high frequency, so I try to avoid that.
Do you mean the processor is at high speed (performance), and throttling is enabled?
So it should not be even surprising.
Quoted 7 lines
Quoted 3 lines
The P4 is able to throttle itself, so I guess the throttling things done externally by the south bridge would have not even been tested by the platform designer...
Uh, I'm not entirely sure I understand what you mean here. The issue is:
when I put the processor in some other T-state than T0, it makes noise. That happens both when it's in P0 or P1.
A CPU have a pin which is used in order to stop execution. By generating a signal which toggle that pin, you throttle down a CPU. If now the circuitry in order to generate that signal contains some cheap capacitors, this may generate sounds.
All you do via ACPI T states is to configure a chipset (most likely the south bridge) in order to generate the signal at a given frequency, and T0 will disable this signal.
All P4 have the ability, though, to throttle without another hardware circuitry. p4-clockmod is the software interface for that feature.
In short, acpi T-state and p4-clockmod will give you the exact same behaviour, but is done diferently, one requiring an external hardware which seems, in your case, to contains cheap components (but that do not matter, since you should use p4-clockmod instead of ACPI T-states anyway).
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Ducrot Bruno -- Which is worse: ignorance or apathy? -- Don't know. Don't care.
Quoted 3 lines · Ducrot Bruno
(but that do
not matter, since you should use p4-clockmod instead of ACPI T-states anyway).
What are the advantages of p4-clockmod in favour of ACPI T-states?
Dominik
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Quoted 7 lines · Dominik Brodowski
Quoted 3 lines · Ducrot Bruno
(but that do
not matter, since you should use p4-clockmod instead of ACPI T-states anyway).What are the advantages of p4-clockmod in favour of ACPI T-states?
1- Latency (MSR access instead of ISA IO space).
2- Safety (p4-clockmod do not rely on external circuitry, or hw bugs from
the southbridge).
3- even though I don't think p4-clockmod do not support this, it is
possible to throttle the CPU in case of overheating issue, without need to do that in software.
4- a little more power efficient, since generating a signal cost power
(but I don't think that you gain so much).
Signature · 4 lines
Ducrot Bruno -- Which is worse: ignorance or apathy? -- Don't know. Don't care.