Messages in this thread | | | Date | Sat, 28 Sep 2002 11:21:30 +0200 | From | Dominik Brodowski <> | Subject | cpufreq patches for 2.5.39 follow |
| |
Hi!
The following patches add CPU frequency and volatage scaling support (Intel SpeedStep, AMD PowerNow, etc.) to kernel 2.5.39.
As was discussed during the 2.5.32 cpufreq thread, the cpufreq patches have been reworked to use a policy-based approach now. A cpufreq policy consists of four values: cpu - the affected CPU nr., or CPUFREQ_ALL_CPUS for all cpus min - minimum frequency in kHz max - maximum frequency in kHz policy - CPUFREQ_POLICY_PERFORMANCE or CPUFREQ_POLICY_POWERSAVE
The interface to userspace is /proc/cpufreq, and the user can "echo" a new policy into this file using the following syntax: [cpu:]min_freq:max_freq:policy or [cpu%]min_pctg%max_pctg%policy
with policy either "powersave" or "performance". The cpu argument is optional.
In cpufreq drivers for "dumb" hardware which can only be set to a specific frequency (and not to a frequency range), one value within the policy range is selected, and the CPU is statically set to this frequency until a new policy is set. "Virtual" dynamic frequency changing is not yet implemented.
For more information, please take a look at the file Documentation/cpufreq in patch 4/5.
The patches, as well as backports to 2.4.19 and 2.4.20-pre7 are also available at http://www.brodo.de/cpufreq/ : http://www.brodo.de/cpufreq/cpufreq-2.5.39-core-1 http://www.brodo.de/cpufreq/cpufreq-2.5.39-i386-core-1 http://www.brodo.de/cpufreq/cpufreq-2.5.39-i386-drivers-1 http://www.brodo.de/cpufreq/cpufreq-2.5.39-doc-1 http://www.brodo.de/cpufreq/cpufreq-2.5.39-24api-1
Patch 1/5: cpufreq-core ----------------------- The cpufreq core offers a common interface to the CPU clock speed features of ARM, PPC and x86 CPUs.
In order for this code to be built, an architecture must define the CONFIG_CPU_FREQ configuration symbol. The i386 code follows in parts 2 and 3, the ARM and PPC ports will most likely follow in the next days or weeks.
Specifically on ARM CPUs, cpufreq_notify_transition is especially important, since various ARM system on a chip implementations derive peripheral clocks from the CPU clock (eg, LCD controllers, SDRAM controllers, etc). The core allows these peripherals to take action either prior and/or after the actual CPU clock adjustment so we don't go out of tolerance. Please note that CPUFREQ_TRANSITION_NOTIFIERS are only called on "dumb" cpufreq hardware. On Transmeta Crusoe processors, where core frequency changes have no external implications, these can safely be ignored.
Patch 2/5: cpufreq-i386-core ---------------------------- The main part of this patch is a CPUFreq transition notifier in arch/i386/kernel/time.c. It updates the i386-specific cpu_khz, cpu_data[].loops_per_jiffy and fast_gettimeoffset_quotient on each frequency change.
Additionally, this patch allows "cpu_khz" to be exported (it is needed for some cpufreq drivers) and adds transmeta-related MSR #defines to asm-i386/msr.h
Patch 3/5: cpufreq-i386-drivers ------------------------------- Six i386 CPUFreq drivers are ready to be merged this time. These are: elanfreq.c: The AMD Elan CPU family offers extensive clock scaling longhaul.c: VIA Longhaul processor clock + voltage scaling longrun.c: Transmeta Crusoe Longrun clock + voltage scaling p4-clockmod.c: clock modulation on P4 Xeon processors powernow-k6.c: mobile AMD K6-2+ / mobile AMD K6-3+ clock scaling speedstep.c: clock and voltage scaling on mobile Intel Pentium 3 and 4s, but (unfortunately) only on ICH2-M or ICH3-M based chipsets.
Support for mobile AMD K7 processors is still in development.
Patch 4/5: cpufreq-doc ---------------------- an entry to the CREDITS and the MAINTAINERS files, Config.help texts, and extensive documentation in linux/Documentation/cpufreq
Patch 5/5: cpufreq-core-24api ----------------------------- Some user-space tools already rely on the "old", one-frequency /proc/sys/cpu/ interface suggested previously. This add-on patch allows a CONFIG option which emulates this interface but still uses the policy interface towards the cpufreq drivers. Please note that the other patches do not rely on this patch and work fine without this patch applied, but only with the /proc/cpufreq interface.
Comments welcome; however please ensure that the cpufreq development list at cpufreq@www.linux.org.uk receives a copy of all comments.
Dominik - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |