path: root/tools/power
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2011-01-11Merge branches 'turbostat' and 'x86_energy_perf_policy' into toolsLen Brown
2011-01-11tools: create power/x86/x86_energy_perf_policyLen Brown
MSR_IA32_ENERGY_PERF_BIAS first became available on Westmere Xeon. It is implemented in all Sandy Bridge processors -- mobile, desktop and server. It is expected to become increasingly important in subsequent generations. x86_energy_perf_policy is a user-space utility to set the hardware energy vs performance policy hint in the processor. Most systems would benefit from "x86_energy_perf_policy normal" at system startup, as the hardware default is maximum performance at the expense of energy efficiency. See x86_energy_perf_policy.8 man page for more information. Background: Linux-2.6.36 added "epb" to /proc/cpuinfo to indicate if an x86 processor supports MSR_IA32_ENERGY_PERF_BIAS, without actually modifying the MSR. In March, 2010, Venkatesh Pallipadi proposed a small driver that programmed MSR_IA32_ENERGY_PERF_BIAS, based on the cpufreq governor in use. It also offered a boot-time cmdline option to override. http://lkml.org/lkml/2010/3/4/457 But hiding the hardware policy behind the governor choice was deemed "kinda icky". In June, 2010, I proposed a generic user/kernel API to generalize the power/performance policy trade-off. "RFC: /sys/power/policy_preference" http://lkml.org/lkml/2010/6/16/399 That is my preference for implementing this capability, but I received no support on the list. So in September, 2010, I sent x86_energy_perf_policy.c to LKML, a user-space utility that scribbles directly to the MSR. http://lkml.org/lkml/2010/9/28/246 Here is that same utility, after responding to some review feedback, to live in tools/power/, where it is easily found. Signed-off-by: Len Brown <len.brown@intel.com>
2011-01-11tools: create power/x86/turbostatLen Brown
turbostat is a Linux tool to observe proper operation of Intel(R) Turbo Boost Technology. turbostat displays the actual processor frequency on x86 processors that include APERF and MPERF MSRs. Note that turbostat is of limited utility on Linux kernels 2.6.29 and older, as acpi_cpufreq cleared APERF/MPERF up through that release. On Intel Core i3/i5/i7 (Nehalem) and newer processors, turbostat also displays residency in idle power saving states, which are necessary for diagnosing any cpuidle issues that may have an effect on turbo-mode. See the turbostat.8 man page for example usage. Signed-off-by: Len Brown <len.brown@intel.com>