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authorLen Brown <len.brown@intel.com>2010-10-22 23:53:03 -0400
committerLen Brown <len.brown@intel.com>2011-01-11 23:02:21 -0500
commitd5532ee7b40b4a64e605e543b0387694430ecb79 (patch)
tree1411d02a42ca83156d37ce6d62c031afc465a5e1 /tools/power/x86/x86_energy_perf_policy/Makefile
parentf6f94e2ab1b33f0082ac22d71f66385a60d8157f (diff)
downloadlinux-linaro-d5532ee7b40b4a64e605e543b0387694430ecb79.tar.gz
tools: create power/x86/x86_energy_perf_policy
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>
Diffstat (limited to 'tools/power/x86/x86_energy_perf_policy/Makefile')
-rw-r--r--tools/power/x86/x86_energy_perf_policy/Makefile8
1 files changed, 8 insertions, 0 deletions
diff --git a/tools/power/x86/x86_energy_perf_policy/Makefile b/tools/power/x86/x86_energy_perf_policy/Makefile
new file mode 100644
index 00000000000..f458237fdd7
--- /dev/null
+++ b/tools/power/x86/x86_energy_perf_policy/Makefile
@@ -0,0 +1,8 @@
+x86_energy_perf_policy : x86_energy_perf_policy.c
+
+clean :
+ rm -f x86_energy_perf_policy
+
+install :
+ install x86_energy_perf_policy /usr/bin/
+ install x86_energy_perf_policy.8 /usr/share/man/man8/