On Tue, 9 Dec 2014 10:43:19 +0900
Ethan Zhao <ethan.z...@oracle.com> wrote:
> To force loading on Oracle Sun X86 servers, provide one kernel command line
> parameter
>
> intel_pstate = force
>
> For those who be 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.z...@oracle.com>
> Tested-by: Alexey Kodanev <alexey.koda...@oracle.com>
> Reviewed-by: Linda Knippers <linda.knipp...@hp.com>
Acked-by: Kristen Carlson Accardi <kris...@linux.intel.com>
> ---
> v2: change to hardware vendor specific naming parameter.
> v4: refine code and doc.
> v5&v6: fix a typo in doc.
> v7: change enum PCC to PPC.
> v8: change the name of kernel command line parameter to generic one.
> v9: refine doc
>
> Documentation/kernel-parameters.txt | 5 +++++
> drivers/cpufreq/intel_pstate.c | 6 +++++-
> 2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/kernel-parameters.txt
> b/Documentation/kernel-parameters.txt
> index 479f332..7d0983e 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1446,6 +1446,11 @@ bytes respectively. Such letter suffixes can also be
> entirely omitted.
> disable
> Do not enable intel_pstate as the default
> 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.
>
> intremap= [X86-64, Intel-IOMMU]
> on enable Interrupt Remapping (default)
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 1bb62ca..2654e13 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -866,6 +866,7 @@ static struct cpufreq_driver intel_pstate_driver = {
> };
>
> static int __initdata no_load;
> +static unsigned int force_load;
>
> static int intel_pstate_msrs_not_valid(void)
> {
> @@ -1003,7 +1004,8 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
> case PSS:
> return intel_pstate_no_acpi_pss();
> case PPC:
> - return intel_pstate_has_acpi_ppc();
> + return intel_pstate_has_acpi_ppc() &&
> + (!force_load);
> }
> }
>
> @@ -1078,6 +1080,8 @@ static int __init intel_pstate_setup(char *str)
>
> if (!strcmp(str, "disable"))
> no_load = 1;
> + if (!strcmp(str, "force"))
> + force_load = 1;
> return 0;
> }
> early_param("intel_pstate", intel_pstate_setup);
--
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