Oh, now I see your confusion. The cpufreq system is organized as drivers and governors which are two separate entities with separate jobs: cpufreq_drivers: example, acpi_cpufreq (Intel), powernow_k8 (AMD) etc. These are responsible for the mechanism of changing the clock speed / voltage. cpufreq_governors: ondemand,conservative,performance etc These are responsible for the policy of how and when should the clockspeed change. You need both The "cpufreq driver" and "cpufreq governor" in order for cpufreq to work. If either one is missing, then the capability is lost. The governor/driver make the cpufreq subdirectory available so you can use/configure it. Let me recommend <kernel Source>/Documentation/cpu-freq/* they will explain things well. 2009/6/12 Randy Dunlap <randy.dunlap@xxxxxxxxxx>: > Amithash Prasad wrote: >> Can you try by configuring the kernel to have the powernow_k8 cpufreq >> driver as a module, and insert it later on? > > Sure, done. And I can see a cpufreq/ sub-directory in each > /sys/devices/system/cpu/cpuX/ now. Thanks. > > but why? Do the other governors not use a cpufreq/ sub-directory? > > > However: I cannot see any significant power vs. performance benefits > on my server system by using cpufreq. Can anyone suggest some > config or /sys settings that might show such benefits? > > Thanks. > >> I have had a few issues when the drivers are compiled into the kernel. >> >> On Thu, Jun 11, 2009 at 10:25 AM, Randy Dunlap<randy.dunlap@xxxxxxxxxx> wrote: >>> Hi, >>> >>> I'm trying to test some cpufreq governors. >>> The target test system is an HP BladeCenter ProLiant BL685c G1. >>> >>> /proc/cpuinfo is at end of this email. >>> >>> I don't see a cpufreq/ directory in /sys/devices/system/cpu/cpuX/ at all. >>> >>> I have loaded 3 cpufreq driver modules: conservative, ondemand, and powersave; >>> and the performance cpufreq driver is built into the kernel image and is >>> the default. >>> >>> >>> Am I doing something wrong? or does this CPU not work with cpufreq? >>> >>> Thanks, >>> -- >>> ~Randy >>> LPC 2009, Sept. 23-25, Portland, Oregon >>> http://linuxplumbersconf.org/2009/ >>> >>> >>> /proc/cpuinfo: >>> >>> processor : 0 >>> vendor_id : AuthenticAMD >>> cpu family : 15 >>> model : 65 >>> model name : Dual-Core AMD Opteron(tm) Processor 8218 >>> stepping : 2 >>> cpu MHz : 2612.360 >>> cache size : 1024 KB >>> physical id : 0 >>> siblings : 2 >>> core id : 0 >>> cpu cores : 2 >>> apicid : 0 >>> initial apicid : 0 >>> fpu : yes >>> fpu_exception : yes >>> cpuid level : 1 >>> wp : yes >>> flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov >>> pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dno >>> wext 3dnow rep_good pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy >>> bogomips : 5224.72 >>> TLB size : 1024 4K pages >>> clflush size : 64 >>> cache_alignment : 64 >>> address sizes : 40 bits physical, 48 bits virtual >>> power management: ts fid vid ttp tm stc >>> >>> processor : 1 >>> vendor_id : AuthenticAMD >>> cpu family : 15 >>> model : 65 >>> model name : Dual-Core AMD Opteron(tm) Processor 8218 >>> stepping : 2 >>> cpu MHz : 2612.360 >>> cache size : 1024 KB >>> physical id : 1 >>> siblings : 2 >>> core id : 0 >>> cpu cores : 2 >>> apicid : 2 >>> initial apicid : 2 >>> fpu : yes >>> fpu_exception : yes >>> cpuid level : 1 >>> wp : yes >>> flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov >>> pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dno >>> wext 3dnow rep_good pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy >>> bogomips : 5223.81 >>> TLB size : 1024 4K pages >>> clflush size : 64 >>> cache_alignment : 64 >>> address sizes : 40 bits physical, 48 bits virtual >>> power management: ts fid vid ttp tm stc >>> >>> processor : 2 >>> vendor_id : AuthenticAMD >>> cpu family : 15 >>> model : 65 >>> model name : Dual-Core AMD Opteron(tm) Processor 8218 >>> stepping : 2 >>> cpu MHz : 2612.360 >>> cache size : 1024 KB >>> physical id : 0 >>> siblings : 2 >>> core id : 1 >>> cpu cores : 2 >>> apicid : 1 >>> initial apicid : 1 >>> fpu : yes >>> fpu_exception : yes >>> cpuid level : 1 >>> wp : yes >>> flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov >>> pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dno >>> wext 3dnow rep_good pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy >>> bogomips : 5223.80 >>> TLB size : 1024 4K pages >>> clflush size : 64 >>> cache_alignment : 64 >>> address sizes : 40 bits physical, 48 bits virtual >>> power management: ts fid vid ttp tm stc >>> >>> processor : 3 >>> vendor_id : AuthenticAMD >>> cpu family : 15 >>> model : 65 >>> model name : Dual-Core AMD Opteron(tm) Processor 8218 >>> stepping : 2 >>> cpu MHz : 2612.360 >>> cache size : 1024 KB >>> physical id : 1 >>> siblings : 2 >>> core id : 1 >>> cpu cores : 2 >>> apicid : 3 >>> initial apicid : 3 >>> fpu : yes >>> fpu_exception : yes >>> cpuid level : 1 >>> wp : yes >>> flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov >>> pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dno >>> wext 3dnow rep_good pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy >>> bogomips : 5223.80 >>> TLB size : 1024 4K pages >>> clflush size : 64 >>> cache_alignment : 64 >>> address sizes : 40 bits physical, 48 bits virtual >>> power management: ts fid vid ttp tm stc >>> ===== > > > -- > ~Randy > LPC 2009, Sept. 23-25, Portland, Oregon > http://linuxplumbersconf.org/2009/ > -- Amithash E. 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