* (no subject) @ 2003-02-03 15:47 Joeri Belis 2003-02-03 16:55 ` CPU throttling?? Seamus 0 siblings, 1 reply; 13+ messages in thread From: Joeri Belis @ 2003-02-03 15:47 UTC (permalink / raw) To: linux-kernel unsubscribe joeri.belis@nollekens.be ^ permalink raw reply [flat|nested] 13+ messages in thread
* CPU throttling?? 2003-02-03 15:47 Joeri Belis @ 2003-02-03 16:55 ` Seamus 2003-02-03 17:00 ` Dave Jones ` (2 more replies) 0 siblings, 3 replies; 13+ messages in thread From: Seamus @ 2003-02-03 16:55 UTC (permalink / raw) To: linux-kernel Just a simple question, Would it be possible to throttle cpu when machine is in idle mode in Linux? or is it purely a BIOS and motherboard functionality. As you know some modern laptops in order to save power, throttle cpu (lower the cpu clock cycles per sec) when in idle mode. Thanks, Seamus ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: CPU throttling?? 2003-02-03 16:55 ` CPU throttling?? Seamus @ 2003-02-03 17:00 ` Dave Jones 2003-02-03 17:04 ` Martin Hermanowski 2003-02-03 17:13 ` John Bradford 2 siblings, 0 replies; 13+ messages in thread From: Dave Jones @ 2003-02-03 17:00 UTC (permalink / raw) To: Seamus; +Cc: linux-kernel On Mon, Feb 03, 2003 at 04:55:13PM +0000, Seamus wrote: > Would it be possible to throttle cpu when machine is in idle mode in > Linux? or is it purely a BIOS and motherboard functionality. > > As you know some modern laptops in order to save power, throttle cpu > (lower the cpu clock cycles per sec) when in idle mode. ACPI does this, CPUFreq does this, and if you're really lucky, there are some APM implementations that do it. Dave -- | Dave Jones. http://www.codemonkey.org.uk | SuSE Labs ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: CPU throttling?? 2003-02-03 16:55 ` CPU throttling?? Seamus 2003-02-03 17:00 ` Dave Jones @ 2003-02-03 17:04 ` Martin Hermanowski 2003-02-03 17:13 ` John Bradford 2 siblings, 0 replies; 13+ messages in thread From: Martin Hermanowski @ 2003-02-03 17:04 UTC (permalink / raw) To: Seamus; +Cc: linux-kernel [-- Attachment #1: Type: text/plain, Size: 437 bytes --] On Mon, Feb 03, 2003 at 04:55:13PM +0000, Seamus wrote: > Just a simple question, > > Would it be possible to throttle cpu when machine is in idle mode in > Linux? or is it purely a BIOS and motherboard functionality. > > As you know some modern laptops in order to save power, throttle cpu > (lower the cpu clock cycles per sec) when in idle mode. http://www.brodo.de/cpufreq/ Works well with my P3m Regards, Martin [-- Attachment #2: Type: application/pgp-signature, Size: 232 bytes --] ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: CPU throttling?? 2003-02-03 16:55 ` CPU throttling?? Seamus 2003-02-03 17:00 ` Dave Jones 2003-02-03 17:04 ` Martin Hermanowski @ 2003-02-03 17:13 ` John Bradford 2003-02-03 18:57 ` Valdis.Kletnieks 2 siblings, 1 reply; 13+ messages in thread From: John Bradford @ 2003-02-03 17:13 UTC (permalink / raw) To: Seamus; +Cc: linux-kernel > Just a simple question, > > Would it be possible to throttle cpu when machine is in idle mode in > Linux? or is it purely a BIOS and motherboard functionality. > > As you know some modern laptops in order to save power, throttle cpu > (lower the cpu clock cycles per sec) when in idle mode. CPU speed throttling is is something is that is currently being worked on. Incidently, Linux has always halted the processor, rather than spun in an idle loop, which saves power. John. ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: CPU throttling?? 2003-02-03 17:13 ` John Bradford @ 2003-02-03 18:57 ` Valdis.Kletnieks 2003-02-03 19:02 ` Dave Jones ` (2 more replies) 0 siblings, 3 replies; 13+ messages in thread From: Valdis.Kletnieks @ 2003-02-03 18:57 UTC (permalink / raw) To: John Bradford; +Cc: Seamus, linux-kernel [-- Attachment #1: Type: text/plain, Size: 452 bytes --] On Mon, 03 Feb 2003 17:13:02 GMT, John Bradford said: > Incidently, Linux has always halted the processor, rather than spun in > an idle loop, which saves power. It's conceivable that a CPU halted at 1.2Gz takes less power than one at 1.6Gz - anybody have any actual data on this? Alternately phrased, does CPU throttling save power over and above what the halt does? -- Valdis Kletnieks Computer Systems Senior Engineer Virginia Tech [-- Attachment #2: Type: application/pgp-signature, Size: 226 bytes --] ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: CPU throttling?? 2003-02-03 18:57 ` Valdis.Kletnieks @ 2003-02-03 19:02 ` Dave Jones 2003-02-03 19:09 ` Martin Hermanowski 2003-02-03 19:14 ` Matt Reppert 2 siblings, 0 replies; 13+ messages in thread From: Dave Jones @ 2003-02-03 19:02 UTC (permalink / raw) To: Valdis.Kletnieks; +Cc: John Bradford, Seamus, linux-kernel On Mon, Feb 03, 2003 at 01:57:17PM -0500, Valdis.Kletnieks@vt.edu wrote: > It's conceivable that a CPU halted at 1.2Gz takes less power than one > at 1.6Gz - anybody have any actual data on this? Alternately phrased, > does CPU throttling save power over and above what the halt does? Given that most decent implementations scale voltage as well as frequency, yes, a lower speed will save more power. Dave -- | Dave Jones. http://www.codemonkey.org.uk ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: CPU throttling?? 2003-02-03 18:57 ` Valdis.Kletnieks 2003-02-03 19:02 ` Dave Jones @ 2003-02-03 19:09 ` Martin Hermanowski 2003-02-03 19:20 ` John Bradford 2003-02-03 19:14 ` Matt Reppert 2 siblings, 1 reply; 13+ messages in thread From: Martin Hermanowski @ 2003-02-03 19:09 UTC (permalink / raw) To: Valdis.Kletnieks; +Cc: John Bradford, Seamus, linux-kernel [-- Attachment #1: Type: text/plain, Size: 599 bytes --] On Mon, Feb 03, 2003 at 01:57:17PM -0500, Valdis.Kletnieks@vt.edu wrote: > On Mon, 03 Feb 2003 17:13:02 GMT, John Bradford said: > > > Incidently, Linux has always halted the processor, rather than spun in > > an idle loop, which saves power. > > It's conceivable that a CPU halted at 1.2Gz takes less power than one > at 1.6Gz - anybody have any actual data on this? Alternately phrased, > does CPU throttling save power over and above what the halt does? If I slow down my 1GHz CPU to 732MHz, I get 15min more (195min total). So it is not much, but noticeable. Regards, Martin [-- Attachment #2: Type: application/pgp-signature, Size: 232 bytes --] ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: CPU throttling?? 2003-02-03 19:09 ` Martin Hermanowski @ 2003-02-03 19:20 ` John Bradford 2003-02-04 14:12 ` Erik Mouw 0 siblings, 1 reply; 13+ messages in thread From: John Bradford @ 2003-02-03 19:20 UTC (permalink / raw) To: Martin Hermanowski; +Cc: Valdis.Kletnieks, assembly, linux-kernel > > > Incidently, Linux has always halted the processor, rather than spun in > > > an idle loop, which saves power. > > > > It's conceivable that a CPU halted at 1.2Gz takes less power than one > > at 1.6Gz - anybody have any actual data on this? Alternately phrased, > > does CPU throttling save power over and above what the halt does? > > If I slow down my 1GHz CPU to 732MHz, I get 15min more (195min total). > So it is not much, but noticeable. Does anybody have any data on frequency throttling on non-X86 architectures? John. ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: CPU throttling?? 2003-02-03 19:20 ` John Bradford @ 2003-02-04 14:12 ` Erik Mouw 0 siblings, 0 replies; 13+ messages in thread From: Erik Mouw @ 2003-02-04 14:12 UTC (permalink / raw) To: John Bradford Cc: Martin Hermanowski, Valdis.Kletnieks, assembly, linux-kernel [-- Attachment #1: Type: text/plain, Size: 459 bytes --] On Mon, Feb 03, 2003 at 07:20:34PM +0000, John Bradford wrote: > Does anybody have any data on frequency throttling on non-X86 > architectures? See http://www.lart.tudelft.nl/projects/scaling/ for papers describing clock&voltage scaling on StrongARM SA-1100. The same page also has my OLS 2002 cpufreq overview paper. Erik -- J.A.K. (Erik) Mouw Email: J.A.K.Mouw@its.tudelft.nl mouw@nl.linux.org WWW: http://www-ict.its.tudelft.nl/~erik/ [-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --] ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: CPU throttling?? 2003-02-03 18:57 ` Valdis.Kletnieks 2003-02-03 19:02 ` Dave Jones 2003-02-03 19:09 ` Martin Hermanowski @ 2003-02-03 19:14 ` Matt Reppert 2003-02-03 19:24 ` Valdis.Kletnieks 2 siblings, 1 reply; 13+ messages in thread From: Matt Reppert @ 2003-02-03 19:14 UTC (permalink / raw) To: Valdis.Kletnieks; +Cc: linux-kernel On Mon, 03 Feb 2003 13:57:17 -0500 Valdis.Kletnieks@vt.edu wrote: > On Mon, 03 Feb 2003 17:13:02 GMT, John Bradford said: > > > Incidently, Linux has always halted the processor, rather than spun in > > an idle loop, which saves power. > > It's conceivable that a CPU halted at 1.2Gz takes less power than one > at 1.6Gz - anybody have any actual data on this? Alternately phrased, > does CPU throttling save power over and above what the halt does? Yes. I have a powerpc laptop that runs at 700 MHz. If I throttle the CPU clock speed down to 400 MHz and change nothing else the battery has noticeably longer life; since it's running slower, it takes less power when it's active (not halted). Matt ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: CPU throttling?? 2003-02-03 19:14 ` Matt Reppert @ 2003-02-03 19:24 ` Valdis.Kletnieks 2003-02-04 14:34 ` Daniel Egger 0 siblings, 1 reply; 13+ messages in thread From: Valdis.Kletnieks @ 2003-02-03 19:24 UTC (permalink / raw) To: Matt Reppert; +Cc: linux-kernel [-- Attachment #1: Type: text/plain, Size: 415 bytes --] On Mon, 03 Feb 2003 13:14:56 CST, Matt Reppert said: > Yes. I have a powerpc laptop that runs at 700 MHz. If I throttle the CPU cloc k > speed down to 400 MHz and change nothing else the battery has noticeably long er > life; since it's running slower, it takes less power when it's active (not > halted). I knew that. The question I asked was whether halted at 700Mhz takes more power than halted at 400Mhz... [-- Attachment #2: Type: application/pgp-signature, Size: 226 bytes --] ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: CPU throttling?? 2003-02-03 19:24 ` Valdis.Kletnieks @ 2003-02-04 14:34 ` Daniel Egger 0 siblings, 0 replies; 13+ messages in thread From: Daniel Egger @ 2003-02-04 14:34 UTC (permalink / raw) To: Valdis.Kletnieks; +Cc: Matt Reppert, linux-kernel [-- Attachment #1: Type: text/plain, Size: 951 bytes --] Am Mon, 2003-02-03 um 20.24 schrieb Valdis.Kletnieks@vt.edu: > I knew that. The question I asked was whether halted at 700Mhz takes more > power than halted at 400Mhz... PowerPC CPUs will shut down unneeded units. There's no such things as a "hlt" instruction. The natural way to slow down the CPU causing more sparetime to shut down single units is to throttle the dispatching of instructions for which there's are flags in the control register set. I've no idea where the frequency scaling should happen but it either needs some hardware clock control or it's the mentioned dispatch throttling. In case of the former there'd be some powersave effects because the power drawn by a CPU is direct proportional to the frequency. In the latter case the difference between an automatically sleeping 700Mhz and a throttled 700Mhz cpu at "400Mhz" should be pretty small, in case the cpu is mostly idle. -- Servus, Daniel [-- Attachment #2: Dies ist ein digital signierter Nachrichtenteil --] [-- Type: application/pgp-signature, Size: 189 bytes --] ^ permalink raw reply [flat|nested] 13+ messages in thread
end of thread, other threads:[~2003-02-04 15:38 UTC | newest] Thread overview: 13+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2003-02-03 15:47 Joeri Belis 2003-02-03 16:55 ` CPU throttling?? Seamus 2003-02-03 17:00 ` Dave Jones 2003-02-03 17:04 ` Martin Hermanowski 2003-02-03 17:13 ` John Bradford 2003-02-03 18:57 ` Valdis.Kletnieks 2003-02-03 19:02 ` Dave Jones 2003-02-03 19:09 ` Martin Hermanowski 2003-02-03 19:20 ` John Bradford 2003-02-04 14:12 ` Erik Mouw 2003-02-03 19:14 ` Matt Reppert 2003-02-03 19:24 ` Valdis.Kletnieks 2003-02-04 14:34 ` Daniel Egger
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