On 12/5/2014 4:40 AM, Ethan Zhao 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.zhao@xxxxxxxxxx>
> Tested-by: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx>
> ---
> 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.
>
> 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 where it may cause problems to
> + happen due to conflicts with platform firmware attempting to
> + drive P-states by itself in certain situations (for thermal
> + control or power capping in general or other purposes).
I suggest something like:
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-state information being
used by the OS and therefore should be used with care.
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.
Maybe this is too specific but I believe it is accurate. Comments?
-- ljk
>
> 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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