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| author |   Len Brown <len.brown@intel.com> | 2010-10-22 23:53:03 -0400 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2011-01-11 23:02:21 -0500 |
| commit | d5532ee7b40b4a64e605e543b0387694430ecb79 (patch) | |
| tree | 1411d02a42ca83156d37ce6d62c031afc465a5e1 /tools/power/x86/x86_energy_perf_policy/Makefile | |
| parent | Linux 2.6.36 (diff) | |
| download | linux-dev-d5532ee7b40b4a64e605e543b0387694430ecb79.tar.xz linux-dev-d5532ee7b40b4a64e605e543b0387694430ecb79.zip | |
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/Makefile | 8 |
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 000000000000..f458237fdd79 --- /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/ |