Messages in this thread | | | Date | Tue, 28 Feb 2006 13:46:29 -0600 | From | Matt Mackall <> | Subject | Re: Status of X86_P4_CLOCKMOD? |
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On Thu, Feb 23, 2006 at 03:41:10PM -0500, Dave Jones wrote: > On Thu, Feb 23, 2006 at 08:59:37PM +0100, Adrian Bunk wrote: > > > > > > config X86_P4_CLOCKMOD > > > > > depends on EMBEDDED > > > > > > > > This one is an x86_64 only issue, and yes, it's wrong. > > > > > > That's for P4, not X86_64... And since P4 clock modulation does not provide > > > almost any energy savings it was "hidden" under embedded. > > > > But the EMBEDDED dependency is only on x86_64: > > > > arch/i386/kernel/cpu/cpufreq/Kconfig: > > config X86_P4_CLOCKMOD > > tristate "Intel Pentium 4 clock modulation" > > select CPU_FREQ_TABLE > > help > > > > arch/x86_64/kernel/cpufreq/Kconfig: > > config X86_P4_CLOCKMOD > > tristate "Intel Pentium 4 clock modulation" > > depends on EMBEDDED > > help > > > > And if the option is mostly useless, what is it good for? > > It's sometimes useful in cases where the target CPU doesn't have any better > option (Speedstep/Powernow). The big misconception is that it > somehow saves power & increases battery life. Not so. > All it does is 'not do work so often'. The upside of this is > that in some situations, we generate less heat this way.
This is perplexing. Less heat equals less power usage according to the laws of thermodynamics.
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