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Using the kernel 2.6.41.4-1.fc15.x86_64 it seems that whenever I boot my laptop on battery power the CPU never gets out of the lowest frequency. $ sudo grep "" /sys/devices/system/cpu/cpu0/cpufreq/* [sudo] password for rui: /sys/devices/system/cpu/cpu0/cpufreq/affected_cpus:0 /sys/devices/system/cpu/cpu0/cpufreq/bios_limit:2001000 /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq:800000 /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq:2001000 /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq:800000 /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_transition_latency:10000 /sys/devices/system/cpu/cpu0/cpufreq/related_cpus:0 1 /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies:2001000 2000000 1600000 1200000 800000 /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors:ondemand userspace performance /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq:800000 /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver:acpi-cpufreq /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor:ondemand /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq:800000 /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq:800000 /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed:<unsupported> Here's how powertop's frequency stats looks: Package | CPU 0 Turbo Mode 0,0% | Turbo Mode 0,0% 2,00 Ghz 0,0% | 2,00 Ghz 0,0% 1,60 Ghz 0,0% | 1,60 Ghz 0,0% 1200 Mhz 0,0% | 1200 Mhz 0,0% 800 Mhz 0,0% | 800 Mhz 0,0% Idle 100,0% | Idle 100,0% | CPU 1 | Turbo Mode 0,0% | 2,00 Ghz 0,0% | 1,60 Ghz 0,0% | 1200 Mhz 0,0% | 800 Mhz 0,0% | Idle 100,0% $ cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 15 model name : Intel(R) Core(TM)2 Duo CPU T7300 @ 2.00GHz stepping : 10 cpu MHz : 800.000 cache size : 4096 KB physical id : 0 siblings : 2 core id : 0 cpu cores : 2 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 10 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm ida dts tpr_shadow vnmi flexpriority bogomips : 3988.73 clflush size : 64 cache_alignment : 64 address sizes : 36 bits physical, 48 bits virtual power management: processor : 1 vendor_id : GenuineIntel cpu family : 6 model : 15 model name : Intel(R) Core(TM)2 Duo CPU T7300 @ 2.00GHz stepping : 10 cpu MHz : 800.000 cache size : 4096 KB physical id : 0 siblings : 2 core id : 1 cpu cores : 2 apicid : 1 initial apicid : 1 fpu : yes fpu_exception : yes cpuid level : 10 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm ida dts tpr_shadow vnmi flexpriority bogomips : 3988.87 clflush size : 64 cache_alignment : 64 address sizes : 36 bits physical, 48 bits virtual power management:
Limiting like this usually happens because the BIOS refuses to go higher. Do the higher frequencies come back again when you plug back in ?