what is throttling?
Hi!
I have googled around for a couple of hours to find out precisely what throttling means. I did it before and found some useful information, but this time I did not find the relevant data.
I would like to find out, which state precisely that the CPU enters when throttling. Maybe it is different from CPU to CPU. Specifically I would like to know if the CPU is completely powered off, my recollection of some information I have seen earlier is that this may be the case.
And where is throttling done in the kernel?
Best regards
Keld
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Quoted 6 lines · Keld Jørn Simonsen
Hi!
I have googled around for a couple of hours to find out precisely what throttling means. I did it before and found some useful information, but this time I did not find the relevant data.
Quoted 6 lines
I would like to find out, which state precisely that the CPU enters when throttling. Maybe it is different from CPU to CPU. Specifically I would like to know if the CPU is completely powered off, my recollection of some information I have seen earlier is that this may be the case.
And where is throttling done in the kernel?
It's managed in the ACPI processor module. Specific, extensive documentation will be added to the ACPI HOWTO soon.
Dominik
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Quoted 10 lines · Keld J?rn Simonsen
Hi!
I have googled around for a couple of hours to find out precisely what throttling means. I did it before and found some useful information, but this time I did not find the relevant data.
I would like to find out, which state precisely that the CPU enters when throttling. Maybe it is different from CPU to CPU. Specifically I would like to know if the CPU is completely powered off, my recollection of some information I have seen earlier is that this may be the case.
On Intel CPUs Throttling means that the CPU skips each other (or more) clock. This is quite slow, but only done to get the temperature down.
AMD CPUs don't have it afaik.
-Andi
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Quoted 12 lines · Andi Kleen
Quoted 10 lines · Keld J?rn Simonsen
Hi!
I have googled around for a couple of hours to find out precisely what throttling means. I did it before and found some useful information, but this time I did not find the relevant data.
I would like to find out, which state precisely that the CPU enters when throttling. Maybe it is different from CPU to CPU. Specifically I would like to know if the CPU is completely powered off, my recollection of some information I have seen earlier is that this may be the case.
Quoted 5 lines
On Intel CPUs Throttling means that the CPU skips each other (or more) clock. This is quite slow, but only done to get the temperature down.
AMD CPUs don't have it afaik.
My AMD system (Duron 1300 + Abit KT7) can be throttled by 50%. In reality it feels more like 90% since even a temperature/fan monitor applet eats 15% of my CPU when throttled. I haven't seen any benefits from throttling though.
Signature · 10 lines
Ville Syrjälä [email protected] http://www.sci.fi/~syrjala/ ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl
Quoted 1 line · Andi Kleen
AMD CPUs don't have it afaik.
ducrot@poupoune:~$ cat /proc/acpi/processor/CPU1/throttling
state count: 8
active state: T0
states:
*T0: 00%
T1: 12%
T2: 25%
T3: 37%
T4: 50%
T5: 62%
T6: 75%
T7: 87%
ducrot@poupoune:~$ uname -m
x86_64though I don't see real usefullness for throttling anyway, so I've not tested if that works.
Cheers,
Signature · 11 lines
Bruno Ducrot -- Which is worse: ignorance or apathy? -- Don't know. Don't care. ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl
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Quoted 16 lines · Bruno Ducrot
Quoted 1 line · Andi Kleen
AMD CPUs don't have it afaik.
ducrot@poupoune:~$ cat /proc/acpi/processor/CPU1/throttling state count: 8 active state: T0 states: *T0: 00% T1: 12% T2: 25% T3: 37% T4: 50% T5: 62% T6: 75% T7: 87%
Quoted 2 lines
though I don't see real usefullness for throttling anyway, so I've not tested if that works.
Indeed. It seems to work different from the Intel implementation though, it doesn't skip clocks.
It's only useful to prevent your machine from melting when the fan fails or someone misdesigns the cooling setup.
-Andi
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Quoted 3 lines · Andi Kleen
It's only useful to prevent your machine from melting when the fan fails or someone misdesigns the cooling setup.
Indeed, but I forgot to say that machine will use powernow-k8 in that case.
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Bruno Ducrot -- Which is worse: ignorance or apathy? -- Don't know. Don't care. ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl
Quoted 3 lines · Bruno Ducrot
though I don't see real usefullness for throttling anyway, so I've not tested if that works.
If throttling can save energy, why not throttling. The few things i do with my computer is coding, doing some word process and listen to mp3. Right now i cant put ACPI working. But if i had i whould throttle because the CPU stays a lot of time idle.
Anil Mamede
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Quoted 11 lines · Anil Mamede
Quoted 3 lines · Bruno Ducrot
though I don't see real usefullness for throttling anyway, so I've not tested if that works.
If throttling can save energy, why not throttling. The few things i do with my computer is coding, doing some word process and listen to mp3. Right now i cant put ACPI working. But if i had i whould throttle because the CPU stays a lot of time idle.
If the CPU is in an idle mode of type C2, throttling doesn't reduce the energy take-in of the CPU.
Dominik
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Quoted 4 lines · Dominik Brodowski
If the CPU is in an idle mode of type C2, throttling doesn't reduce the energy take-in of the CPU.
The CPU change modes automatically?
Anil Mamede
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Quoted 4 lines · Anil Mamede
Quoted 2 lines
If the CPU is in an idle mode of type C2, throttling doesn't reduce the energy take-in of the CPU.
The CPU change modes automatically?
Not the CPU, the ACPI processor module automatically changes CPU power states (working / C1 / C2 / C3) if these are supported.
Dominik
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Quoted 11 lines · Anil Mamede
Quoted 3 lines · Bruno Ducrot
though I don't see real usefullness for throttling anyway, so I've not tested if that works.
If throttling can save energy, why not throttling. The few things i do with my computer is coding, doing some word process and listen to mp3. Right now i cant put ACPI working. But if i had i whould throttle because the CPU stays a lot of time idle.
You don't really want throttling, it takes a long time to get out of and is quite slow. Result is that the desktop becomes very unresponsive.
-Andi
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