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intel_pstate: add kernel parameter to force loading 

To force loading on Oracle Sun X86 servers, provide one kernel command line
parameter

  intel_pstate = force

For those who are aware of the risk of no power capping capabily working
and try to get better performance with this driver.

Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>
Tested-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Reviewed-by: Linda Knippers <linda.knippers@hp.com>
Acked-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Ethan Zhao 2014-12-09 10:43:19 +09:00 committed by Rafael J. Wysocki
parent 966916eabf
commit aa4ea34da9
2 changed files with 14 additions and 1 deletions
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9
Documentation/kernel-parameters.txt
View File

@ -1446,6 +1446,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
disable disable
Do not enable intel_pstate as the default Do not enable intel_pstate as the default
scaling driver for the supported processors scaling driver for the supported processors
force
Enable intel_pstate on systems that prohibit it by default
in favor of acpi-cpufreq. Forcing the intel_pstate driver
instead of acpi-cpufreq may disable platform features, such
as thermal controls and power capping, that rely on ACPI
P-States information being indicated to OSPM and therefore
should be used with caution. This option does not work with
processors that aren't supported by the intel_pstate driver
or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
no_hwp no_hwp
Do not enable hardware P state control (HWP) Do not enable hardware P state control (HWP)
if available. if available.

6
drivers/cpufreq/intel_pstate.c
View File

@ -948,6 +948,7 @@ static struct cpufreq_driver intel_pstate_driver = {
static int __initdata no_load; static int __initdata no_load;
static int __initdata no_hwp; static int __initdata no_hwp;
static unsigned int force_load;
static int intel_pstate_msrs_not_valid(void) static int intel_pstate_msrs_not_valid(void)
{ {
@ -1094,7 +1095,8 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
case PSS: case PSS:
return intel_pstate_no_acpi_pss(); return intel_pstate_no_acpi_pss();
case PPC: case PPC:
return intel_pstate_has_acpi_ppc(); return intel_pstate_has_acpi_ppc() &&
(!force_load);
} }
} }
@ -1175,6 +1177,8 @@ static int __init intel_pstate_setup(char *str)
no_load = 1; no_load = 1;
if (!strcmp(str, "no_hwp")) if (!strcmp(str, "no_hwp"))
no_hwp = 1; no_hwp = 1;
if (!strcmp(str, "force"))
force_load = 1;
return 0; return 0;
} }
early_param("intel_pstate", intel_pstate_setup); early_param("intel_pstate", intel_pstate_setup);