Recently I've been trying to investigate why my laptop is so slow. I found out that it runs at ~600Mhz, regardless of the power supply being plugged in or not. Note that it's Intel i5-2540M nominally running at 2.60GHz. So I find it very strange to be clocked at ~600Mhz all the time, even if it's loaded with some computations. This even affect web browsing, so it's quite annoying.
I further investigated this issue and it turns out the clock is related to so called CPU governor mode. On my system it's always set to
powersave, no matter if the power supply is plugged in or not. I think it should be switched to
performance mode (or something in between, if possible) when the power supply is plugged in. Note that switching to
performance mode manually solves the problem - the laptop becomes much more responsive.
Does Ubuntu have any support for such automatic switching of CPU governor modes? Is there any package I should install or a configuration file which I need to edit?
I am aware of the
pm-utils package which provides some power related notifications so I could use it as the foundation of a simple script which does the CPU governor switching fully automatically. Still I might be unaware of some limitations or gotchas of such an approach. So I want to know if this is the right one.
Thanks in advance!
BTW, my setup is Ubuntu 14.10
$ uname -a Linux aromanek-laptop 3.16.0-34-generic #47-Ubuntu SMP Fri Apr 10 18:02:58 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux $ cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 42 model name : Intel(R) Core(TM) i5-2540M CPU @ 2.60GHz stepping : 7 microcode : 0x12 cpu MHz : 633.242 cache size : 3072 KB physical id : 0 siblings : 4 core id : 0 cpu cores : 2 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 13 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 rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm ida arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid bogomips : 5188.00 clflush size : 64 cache_alignment : 64 address sizes : 36 bits physical, 48 bits virtual power management:
$ cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver intel_pstate intel_pstate intel_pstate intel_pstate $ sudo cat /sys/kernel/debug/pstate_snb/d_gain_pct 0 $ sudo cat /sys/kernel/debug/pstate_snb/p_gain_pct 20 $ sudo cat /sys/kernel/debug/pstate_snb/i_gain_pct 0